Microfilms (or: will there ever be a new CMS20?)

[Chuck1]

So the immediate question is : will we have some CMS 20 II in 120 format in a near future or not ?

Sounds like cms 20 ii
Is only 35mm only from fotoimpex.

 

[destroya]

So the immediate question is : will we have some CMS 20 II in 120 format in a near future or not ?

no. They are not making any more, so the only things they wil be selling is the remaining 4x5 and 35mm singe rolls only. ADOX talked about it in the cms 20 thread. the say "We have no more raw material." and

CMS 20 base film emulsion is no longer coated. The EPM shutdown affected all microfilm productions.
We have enough stocks to carry us through another 1-2 years with CMS 20.
The remaining stocks are available through Fotoimpex exclusively and we limited orders to 10 rolls to stretch the stock as long as possible.
As an alternative we recomend our outstanding HR-50 which is already extremely fine grained and higher resolving than e.g. APX 25 or KB25 ever were. In short we plan to release a special developer which yields even finer grained images with this film if shot at 25 ASA. This film is sold in much larger quantities and can therefore be offered at a lower price as well.

https://www.photrio.com/forum/threads/adox-cms-20-ii-availability-in-us.205962/

 

[MsLing]

Sadly.No more new CMS is a disaster.But when 120 format HR-50 can be available again?Only Rollei Retros I can get now.High resolution film is amazing and funny for me.

 

[Crysist]

1. I'm not sure I understand your logic. How is "half the 1000:1 resolution" for the Fuji's films supporting "you'll reach close to that with more modest contrasts" ?

The difference between 1000:1 and 1.6:1 is quite large, so the fact that Fuji has measurements attesting 1.6:1 at half the spatial frequency of 1000:1, other object contrasts the lie between (and which are common in a scene) should stand to reason as being able to be resolved. Henning mentioned that even those are conservative measurements.

But you're right, it's only a handwavey justification and based on something I have not measured myself. I'm just referencing this statement by ADOX in an older thread and trying to paint a picture how I charitably connect the dots in my head:

The behaviour of resolution in its dependency on object contrast is not completely linear over the whole range from 1.6:1 to 1000:1. That is very important to know!!
To put it in other words and make it more clear: To come close to the resolution value of the 10 stops (1000:1) of 200 lp/mm you don't need 8 or 9 stops difference, but only 4-5 stops.
For example Carl Zeiss has achieved 180 lp/mm resolution with TMX with that 4-5 stop contrast. And such a contrast is not seldom in normal shooting conditions.
We have seen TMX examples with resolution of about 135 lp/mm at an object contrast of only 4:1 = two stops (that were results by Mr. Serger).
And both the Zeiss and Serger results were achieved with normal equipment which is available for every photographer.
So we have the "law of diminishing returns" here: From 1.6:1 to 16:1 or 32:1 you have a quite linear response, and with even higher object contrasts the curve is significantly flattening.
The resolution is quite high already in the low(er) to low-medium contrast range.

Sorry for the vagueness, I should have found that post and quoted it directly in my reply.

2. Pyrocat-HD is a low or high contrast developer like most others, depending on how you use dilution/time.

Right! So what properties does it have compared to the "standard" developers? (HC110, D76, uhm you know those ones...)

 

[Scott J.]

So what properties does it have compared to the "standard" developers? (HC110, D76, uhm you know those ones...)

Pyrocat-HD has several benefits:

1) It produces negatives with extremely fine grain and extremely high acutance, which is pretty unusual. For most film-developer combinations, those two qualities exist in opposition to each other. For example, solvent-type developers like D-76 achieve fine grain via dissolution of grain boundaries, which necessarily results in lower acutance. Kodak Xtol/Adox XT-3 are probably the only "mainstream" developers I've tested that are capable of getting somewhat close to producing the same combination of fine grain and high acutance, but the Pyrocat still edges them out to my eye. For anyone who wants those benefits but doesn't want to tinker with novel developers like Pyrocat, I think XT-3 is a great off-the-shelf alternative (I would just advise developing for less time than what is published for Kodak Xtol, as Adox's XT-3 produces considerably denser highlights based on my testing with FP4+ control strips).

2) It can effectively act as a compensating developer to control highlight density, which is useful in photographing scenes with high contrast (typical for landscape photography on sunny days). It's not unique in this regard, but it is another feather in its cap.

3) The glycol-based version has excellent shelf life (years).

4) It's inexpensive on a per-film basis, primarily because the working solutions are prepared using very low concentrations (i.e., 1+1+98 is a typical dilution).

5) The formula is published, so you can make it from raw chemicals if necessary (or desired).

Basically, it has all of the most important benefits of Rodinal, but with the addition of producing very fine grain.

There are a couple downsides, however. First, one of its components (pyrocatechol) is more toxic than most photographic chemicals, so you need to take some basic precautions when handling it (e.g., common-sense things like wearing gloves, not inhaling or ingesting it, etc.). Second, the published developing times are pretty sparse for anything other than a few conventional films (e.g., Ilford FP4+, HP5, etc.), so you'll likely need to do some experimenting to really nail down an exposure index and developing routine for your film of choice. Visual inspection of negatives on a light table is generally good enough to determine proper development (if using a densitometer, use the Blue channel measurements, as the visual channel gets thrown off by the brown color of the stain).

 

[250swb]

Kodak Xtol/Adox XT-3 are probably the only "mainstream" developers I've tested that are capable of getting somewhat close to producing the same combination of fine grain and high acutance, but the Pyrocat still edges them out to my eye. For anyone who wants those benefits but doesn't want to tinker with novel developers like Pyrocat,

I've been using Adox HR-50 II recently and developing it in Adox FX-39 II just because I had a bottle but already knew it was good with slow films. And I thought 'Wow!' but couldn't put my finger on what I liked about it besides the fine grain and sharpness of the combination. There isn't much out there about HR-50 or FX39 and the Adox datasheets are poor, so delving deeper I found this developer review and thought 'that's it, it's the best parts of Rodinal and Xtol combined'.

http://www.alexluyckx.com/blog/2020/12/22/developer-review-blog-no-12-adox-fx-39-ii/

and then this film review of the HR-50 and FX-39 combination

http://www.alexluyckx.com/blog/2021/08/09/film-review-blog-no-74-adox-hr-50/

 

[ADOX Fotoimpex]

So the immediate question is : will we have some CMS 20 II in 120 format in a near future or not ?

Yes because we have some master rolls slit into 60mm pancakes but then we are out of master rolls and cannot continue this. Its a limited supply one time only show unfortunately.

 

[Chuck1]

Not to belabor the point but
Cms ii 120 will become available?
Only at fotoimpex?

 

[Crysist]

Apologies in advance for showering everyone in questions... wait I think I already did that. *More questions.

Pyrocat-HD has several benefits:

1) It produces negatives with extremely fine grain and extremely high acutance, which is pretty unusual. For most film-developer combinations, those two qualities exist in opposition to each other. For example, solvent-type developers like D-76 achieve fine grain via dissolution of grain boundaries, which necessarily results in lower acutance. Kodak Xtol/Adox XT-3 are probably the only "mainstream" developers I've tested that are capable of getting somewhat close to producing the same combination of fine grain and high acutance, but the Pyrocat still edges them out to my eye. For anyone who wants those benefits but doesn't want to tinker with novel developers like Pyrocat, I think XT-3 is a great off-the-shelf alternative (I would just advise developing for less time than what is published for Kodak Xtol, as Adox's XT-3 produces considerably denser highlights based on my testing with FP4+ control strips).

2) It can effectively act as a compensating developer to control highlight density, which is useful in photographing scenes with high contrast (typical for landscape photography on sunny days). It's not unique in this regard, but it is another feather in its cap.

Oh, that's really neat! Most of these aspects seem counteractive to each other. I figured higher contrast films would tend to have higher acutance. But if there are developers that can improve the result along each "dimension", it seems like they're not always linked.

For example, if you have one of those low-contrast areas with fine detail (such as having the aforementioned 1.6:1 object contrast), would a low-contrast developing make that detail lost while high-contrast development would retain it?

5) The formula is published, so you can make it from raw chemicals if necessary (or desired).

Regarding developer formulations in general: is it typically the case that there isn't much to gain by testing different proportions yourself because the the author of the original formula likely already did that? Dialed in the exact amounts to give the best results? I am curious what people go through to devise a developer recipe. Just a ton of testing? Use entire bulk-rolls of film to find results you like the best?

Basically, it has all of the most important benefits of Rodinal, but with the addition of producing very fine grain.

There are a couple downsides, however. First, one of its components (pyrocatechol) is more toxic than most photographic chemicals, so you need to take some basic precautions when handling it (e.g., common-sense things like wearing gloves, not inhaling or ingesting it, etc.). Second, the published developing times are pretty sparse for anything other than a few conventional films (e.g., Ilford FP4+, HP5, etc.), so you'll likely need to do some experimenting to really nail down an exposure index and developing routine for your film of choice. Visual inspection of negatives on a light table is generally good enough to determine proper development (if using a densitometer, use the Blue channel measurements, as the visual channel gets thrown off by the brown color of the stain).

Besides the hazard of the pyrocatechol, determining the right developing times I feel is common in "home darkroom" cases, no? You at least need to do a lot of testing when printing. It doesn't sound too bad to need to do that for the original development.

Is the staining aspect of any note? Do some people also use it for being a staining developer? Do some of the properties come from it being staining?

Yes because we have some master rolls slit into 60mm pancakes but then we are out of master rolls and cannot continue this. Its a limited supply one time only show unfortunately.

Does ADOX have any interest in films of a similar nature? Ultra-fine grain films? I'm not familiar with film coating and what effort goes into introducing different coatings and managing available coating facilities appropriately - like if you could do runs of film X between higher volumes of Y.

If CMS 20 was a microfilm that was made to shine through a developer that could tame its high gamma, could the same not be done with other microfilms? I mentioned the Fuji HR line, I don't know the production/distribution situation with it, however. Or, since CMS 20 is a relatively simple film in the design of its emulsion, could a similar film be made? Or a film that is better?

 

[Scott J.]

For example, if you have one of those low-contrast areas with fine detail (such as having the aforementioned 1.6:1 object contrast), would a low-contrast developing make that detail lost while high-contrast development would retain it?

That's an interesting question. My instinct is that a low-contrast developer might lose some of that detail compared to a "normal" contrast developer, but I'm not confident to stake anything on that. In general, I think the more important aspect of the "low-contrast developer" versus "normal-contrast developer" divide is about how they each react differently to areas of weak and strong latent image in the emulsion (i.e., a low-contrast developer is able to accomplish development of shadows without overdeveloping highlights).

is it typically the case that there isn't much to gain by testing different proportions yourself because the the author of the original formula likely already did that?

In the case of less-mainstream developers like Pyrocat-HD, it can be difficult to find reliable advice. Some kind of testing -- even if it's just based on comparing negatives of the same scene on a light table, where each negative has been exposed and/or developed differently -- is a good idea. I've done full Zone System-style testing on Pyrocat-HD and several films, and I think it was worth the time. This involved using a 4x5 Stouffer Step wedge and a calibrated color densitometer (X-Rite 811), as I wanted to have a repeatable method of quantitatively judging the effects of changing exposure index (EI) and development routine. FP4+ was about the only film for which I could find enough suggested starting points online that more or less agreed with each other. The trouble here is that, because different photographers standardize on different temperatures, different agitation methods, different dilutions, etc., you sort of have to "average" their recipes out to find a starting point. When I finally found EIs and development routines that gave me the range of densities that I wanted in those films, a couple of them fell more or less in line with what I had expected from reading forums online while a couple were wildly different. Delta 100, in particular, required considerably less development in Pyrocat-HD than what people were suggesting (at least, that was my result).

As I alluded to previously, however, one thing I learned from all this work is that you don't really need to do a full test of this kind to get good, repeatable results in your film photography. If you're experienced with looking at negatives, examination on a light table can tell you if need to make major adjustments to exposure (i.e., to change shadow density) or development (i.e., to change highlight density). Similarly, if you scan your film, the histogram in the scanning software can give you some really useful information about what's right or wrong with your film. If the information in an average scene is bunched up at the right-hand side of the histogram (too bright), you're probably overdeveloping; if it's bunched up at the left-hand side (too dark), you're probably underexposing. An important thing is to stick with just one film and developer for a while. That's the only way you'll become familiar enough with them to notice patterns in how EI and development affect the final result.

Is the staining aspect of any note? Do some people also use it for being a staining developer? Do some of the properties come from it being staining?

My understanding is that the stain in such developers does several things:

1) They harden the film emulsion in a chemical process that's similar to leather tanning. The hardening of the emulsion reduces the amount of grain boundary migration that occurs during development. As a result, you get more strongly demarcated grain boundaries, which improves apparent sharpness.

2) The stain forms in proportion to the strength of the latent image, and as a result, there's less stain in the shadows and more stain in the highlights. Simultaneously, the formation of the stain attenuates the creation of additional metallic silver. This does a couple things: a) it can help prevent overdevelopment of highlights (i.e., compensational development); and b) by attenuating the formation of additional metallic silver, the final image density is comprised of stain + metallic silver, which is inherently less grainy than density that's comprised of metallic silver alone.

3) The stain fills in the gaps between adjacent silver grains. As a result, areas of continuous tone in the image look more... well, continuous... because there's less grain-to-grain drop off in density. This helps to reduce the appearance of grain.

 

[Henning Serger]

Thanks for the extra information, Henning.

My pleasure, Mark.

In the days when I was doing these tests ( c.1995 ) I was checking the negs by eye on a microscope at work. The 'target' for the lens was a home-made sector target drawn at A3 , then reduced and printed onto glossy photo paper. I could only roughly judge where the detail smeared out into grey - no doubt a better way of scanning and graphing the neg would have yielded more accurate results.
I can't remember what the developer was - but I think I had one of the Kodak T-Max developers.

I am also using a microscope, which offers several lenses and enlargement factors. Evaluation at 40x and 100x enlargement is a standard in my film and lens resolution tests.
My used test-chart is from test-chart specialist DANES-PICTA (my used version is optimal for film and high resolution tests, but not available anymore).

ps. overall the best lens I ever tested , in 1998 while at Zeiss, was the Zeiss Contax 21mm f/2.8

Not surprising, as this lens has an excellent reputation. I well remember the times about 20 years ago when Canon photographers discovered the outstanding quality of that lens and started adapting it to the EF mount. Prices on the used market for the lens than increased so much that often they surpassed even the former new price!

By the way, this excellent lens is still made new:
As Zeiss Milvus Distagon 2,8/21mm ZE (Canon EF mount) and ZF.2 (Nikon F mount). AFAIK the optics are more or less unchanged, just an improved coating added.
The mechanics of the current Milvus version are significantly improved, and also offer full sealing and dust and moisture protection in the lens, and on the bayonet.

Best regards,
Henning

 

[Donald Qualls]

One thing, if there's another run (from the already cut 60 mm pancakes) of 120, those of us who shoot submini can buy it and have a field day. One roll of 120 will make six Minolta 16 reloads (they'll be short rolls in a Kiev 30/30M/303, though), or six rolls of 50 exposures (or a dozen of 24) for Minox. I plan to buy several rolls if/when CMS 20 II shows up again in 120, since I'm planning to get a Minox soon...

 

[Henning Serger]

I wrote a bit much, decided to actually split my post in half...


HENNING IS HERE!

Please excuse me as I talk your ear off.

I've seen you use the Makro Planar Zeiss in your tests for a while now, but unless it works far better in the macro range, shouldn't there be tons of examples that far exceed the Makro Planar by now?

Well, your assessment of the Zeiss (Milvus) Makro-Planar 2/50mm is not correct:
It does not work far better in the macro range compared to normal distances like most other macro lenses do (which are often weaker at longer distances).

The Makro-Planar is an excellent all-round lens:
- Excellent performance at infinity
- Excellent performance at medium distances
- Excellent performance at close distances
- Excellent performance at macro distances.

This great versatility was one of the main reasons why I had bought that lens. At all theses distances it surpasses all of my 50mm Nikkor primes.

And that I am using it for my film tests is mainly for standardisation reasons: For my film tests I need total comparability. The test conditions have to be absolutely the same for all tested films, including new ones which hit the market. Therefore the same lens at the same aperture (f5.6, at which this lens offers the best performance) must be and is used.

Yes, there are some even better lenses on the market. I plan to publish some results in the future.

There seem to be no less than half a dozen lens manufacturers that are selling optics with multiple aspheric surfaces.

Aspheric surfaces offer the lens designer more freedom in design and more options. But they are also no guarantee for significantly better performance.
Very often they are used the reduce the number of needed elements in a lens to make it more compact.

Laowa sells a 15mm f/2 M mount lens that outresolves that $4000 Zeiss 15mm f/2.8 ZM lens,

Evidence for that?

Voigtlander seems to have significantly upped it's line with many heavy hitters. Sigma has its ART series that is attested to perform stellar at maximum aperture.

Yes, both Voigtländer and Sigma with the Art series have introduced really outstanding lenses, which offer excellent additional value especially for film photographers.
The same is also valid for Zeiss with the Otus and Milvus lens lines. And the modern Leica lenses for the M cameras.

Canon and Nikon have produced some great (but heavy) lenses for their mirrorless lines, ones which are very affordable for having MTF charts that look more and more ultra-perfect telephoto lenses.

Not only mirrorless: You will also find many modern Canon EF mount and Nikon F mount SLR lenses which are excellent and very significantly surpass their forerunners which were designed in the 60ies, 70ies and 80ies.

Just two examples:
- Nikon Nikkor AF-D 2/105 DC. Completely surpasses the excellent and very famous Nikkor 2,5/105 AI-S ( I have and use both lenses for many years). The 2/105 DC is one of the best lenses Nikon ever produced.
- Nikkor AF-S 1.8/24mm G ED. It blows the very popular 2.8/24 Nikkor "out of the water". The older 2.8/24 Nikkor has its "sweet spot" with optimal performance at f8. But the same level of resolution, sharpness and contrast I get at f8 with the older 2.8/24 I already get at f2.8 (!!) with the modern, current AF-S 1.8/24 Nikkor.
So a 3 stop advantage in optical performance. That is huge. Means you often could use ADOX HR-50 instead of HP5+ or Tri-X. And that makes really a huge difference!

But on that note, you state exactly why these films are appealing to me as well! You can get so much out of even modest equipment that you'd otherwise be throwing away, and while resolution is not everything about photography, it certainly is fun to see what small details you can capture with your entire setup!

Yes, that is correct.
My personal approach in 35mm photography: I love the versatility and all the numerous advantages this format has compared to medium format.
But I also love medium format quality, because I like to make bigger prints.
Therefore for me all is welcome which
- brings my 35mm results closer to the medium format quality level
- offer me (almost) medium format quality with 35mm.

And here the latest, much improved lenses for 35mm play an important role, because they
- offer significantly improved performance to older 35mm lens designs
- offer also improved performance compared to medium format lenses (where we are restricted in most cases to old(er) designs, and much slower lenses)
- offer much improved performance at wider apertures and open aperture.

With the older prime lens designs, you have to stop down 3-4 stops to get the optimal results. And performance at max. open aperture is relatively weak.
That is very different with most modern prime lenses: You often get very good and full usable performance at open aperture of f1.4 or f1.8. You then already get excellent performance only one stop stopped down, and perfect performance ("sweet spot") only 2-3 stops stopped down.
Example: My Zeiss Milvus Planar 1.4/85 ZF.2 offers already at f1.4 the same sharpness as my Nikkor 2.5/105 at f4 (!!).

With the modern, significantly improved 35mm lenses I get a performance advantage of 1-3 stops, dependent on the specific lens.
Which also means that I often can use an ISO 100/21° film instead of ISO 200/24°.
Or ISO 100/21° instead of 400/27°.
Or even ISO 50/18° instead of 400/27°.
And the lower speed films offer significantly higher resolution, better sharpness and finer grain. They can be enlarged to bigger formats with excellent quality.

In medium format I have the disadvantage of slower lenses compared to 35mm.
My Zeiss 2/50 offers significantly better performance at f2.8 compared to the Mamiya Sekor C 2.8/80 at f2.8 (and the Sekor is a very good lens).
The Milvus Planar 1.4/85 offers at f2.8 much better performance compared to the Sekor 2.8/150 A (which belongs to best medium format lenses, by the way).
The Sigma Art 1.4/35 at f2.8 surpasses the (also excellent) Sekor C 2.8/55 at f2.8.

With the modern 35mm primes you can often use ISO 50/18° or ISO 100/21° films, when in medium format ISO 400/27° is needed. Equalizing the medium format advantage. Sometimes even surpassing MF.

With these modern 35mm format lenses and their excellent performance wide open and slightly stopped down usage of CMS 20 II and HR-50 / SCALA 50 becomes much more easy and comfortable.
Using HR-50 as a kind of "standard film" with these lenses is possible. And HR-50 in 35mm format with the extremely fine grain, excellent resolution and sharpness really offers you a medium format quality level.

Heck, even the past 10 have seen such great designs pop up. I think I saw in another thread that for resolution, people were preferring smaller formats over larger because the lenses were getting better.

General rule is: The smaller the lens diameter, the higher the resolution. In general (there are some exceptions) medium format lenses have higher resolution than large format lenses, and lenses for 35mm format have higher resolution than medium format lenses.

My primes for 35mm format all surpass my medium format lenses of the equivalent focal length in resolution.

Still bakes my noodle. Like, sure, I see the diagrams but how are you focusing on the focal point and that just works?

Focussing is really the bottleneck for high(est) resolution results (if you have a subject with no depth like a resolution test chart). And neither manual focussing aids lite split-image indicator or microprisms, nor the best AF systems are absolutally precise. You have a bit of variation from focussing process to focussing process. Therefore for my resolution test I use a kind of focus bracketing method: I make many shots (in case of film a whole 36exp. film), and each one is newly/freshly focussed. By that I obtain definitely at least several photos which are perfect in focus.

I saw a user who held Kodachrome 25 in the highest regard and was trying to vouch for it being far better than the datasheets said on photo.net. He did present a drumscan of a slide shot with a Schneider 50mm f/2 from, I believe, and old Retina and said that he saw more detail under his microscope than the scan captured at 6000 dpi.

That is realistic, as resolution of Kodachrome 25 has been indeed much higher than a 6000ppi scan.
The same is also valid for all ISO 100/21° E6 positive films of the last 20 years, and for Provia 400X. And for Delta 100, Acros, TMX, HR-50, CMS 20 II.....etc.

And I feel from seeing your tests, and tests from others including Tim Parkin and Dominique Ventzke, that the results you can get (and see) are far better than people have touted for a long time as "only achievable with an expensive drum scanner".

Correct. And with optical enlargement with the best enlarging lenses, and with slide projection with the best projection lenses you get the best results with film. Significantly higher resolution compared to even the best drum scanners, or camera scanning with the highest MP cams.

One thing I'm sure others have asked: does the bayer filter affect these results any amount?

Yes, but not in a dramatic way. The biggest bottleneck for sensor resolution is just the Nyquist frequency.

Was Gigabitfilm itself an existing microfilm stock with a special developer?

Yes, existing film: It was Agfa Copex Rapid with a special developer for it.
Gigabitfilm was at first a cooperation of photo-engineer Heribert Schain from SPUR and D. Ludwig. The cooperation stopped because of differences about the developer quality: H. Schain wanted to improve the quality before market introduction, D. Ludwig wanted the market introduction at that time (early 2000s).
Schain was right in the end as the Gigabitfilm developer had weaknesses, and Gigabitfilm was no success in the market.

Heribert Schain of SPUR invested in further R&D and introduced his own improved SPUR developers for Agfa COPEX Rapid. The latest, current version is SPUR Dokuspeed SL-N. And Agfa Copex Rapid is still available as SPUR DSX film.

Best regards,
Henning

 

[Crysist]

That's an interesting question. My instinct is that a low-contrast developer might lose some of that detail compared to a "normal" contrast developer, but I'm not confident to stake anything on that. In general, I think the more important aspect of the "low-contrast developer" versus "normal-contrast developer" divide is about how they each react differently to areas of weak and strong latent image in the emulsion (i.e., a low-contrast developer is able to accomplish development of shadows without overdeveloping highlights).

Right, I see. The reason I asked is because something like Adotech is meant to make the extreme contrast of CMS 20 useable. Would there be any gain in the performance of these low object contrasts by using a less suited developer than Adotech, that's what I was wondering. Likewise, are you losing detail when you use low-contrast developers? I know sharpness is in part a perceptual aspect, but if that "information" is retained, would printing at higher contrast suddenly reveal textures and detail in areas that otherwise looked flat and not delineating any details like that?

In the case of less-mainstream developers like Pyrocat-HD, it can be difficult to find reliable advice. Some kind of testing -- even if it's just based on comparing negatives of the same scene on a light table, where each negative has been exposed and/or developed differently -- is a good idea. I've done full Zone System-style testing on Pyrocat-HD and several films, and I think it was worth the time. This involved using a 4x5 Stouffer Step wedge and a calibrated color densitometer (X-Rite 811), as I wanted to have a repeatable method of quantitatively judging the effects of changing exposure index (EI) and development routine. FP4+ was about the only film for which I could find enough suggested starting points online that more or less agreed with each other. The trouble here is that, because different photographers standardize on different temperatures, different agitation methods, different dilutions, etc., you sort of have to "average" their recipes out to find a starting point. When I finally found EIs and development routines that gave me the range of densities that I wanted in those films, a couple of them fell more or less in line with what I had expected from reading forums online while a couple were wildly different. Delta 100, in particular, required considerably less development in Pyrocat-HD than what people were suggesting (at least, that was my result).

As I alluded to previously, however, one thing I learned from all this work is that you don't really need to do a full test of this kind to get good, repeatable results in your film photography.

That's a relief! It seems a bit silly that for some films you'd need to use a bunch of resources and time and perhaps finnicky methods to try to determine the times and concentrations.

My understanding is that the stain in such developers does several things:

1) They harden the film emulsion in a chemical process that's similar to leather tanning. The hardening of the emulsion reduces the amount of grain boundary migration that occurs during development. As a result, you get more strongly demarcated grain boundaries, which improves apparent sharpness.

2) The stain forms in proportion to the strength of the latent image, and as a result, there's less stain in the shadows and more stain in the highlights. Simultaneously, the formation of the stain attenuates the creation of additional metallic silver. This does a couple things: a) it can help prevent overdevelopment of highlights (i.e., compensational development); and b) by attenuating the formation of additional metallic silver, the final image density is comprised of stain + metallic silver, which is inherently less grainy than density that's comprised of metallic silver alone.

3) The stain fills in the gaps between adjacent silver grains. As a result, areas of continuous tone in the image look more... well, continuous... because there's less grain-to-grain drop off in density. This helps to reduce the appearance of grain.

Fascinating! I am trying to build up a little mental corpus, or maybe some notes, of what broad categories developers fall into, what they do, why they do that, etc. Thank you very much for your thorough and detailed answers!!

Well, your assessment of the Zeiss (Milvus) Makro-Planar 2/50mm is not correct:
It does not work far better in the macro range compared to normal distances like most other macro lenses do (which are often weaker at longer distances).

The Makro-Planar is an excellent all-round lens:
- Excellent performance at infinity
- Excellent performance at medium distances
- Excellent performance at close distances
- Excellent performance at macro distances.

This great versatility was one of the main reasons why I had bought that lens. At all theses distances it surpasses all of my 50mm Nikkor primes.

Ah, excuse me for that. I was just coming from the observation that I'd see these "perfect" looking figures for sharpness in some telephoto lenses, where on MTF graphs the lines would all overlap at 100%, and was wondering why people didn't use them instead.

And that I am using it for my film tests is mainly for standardisation reasons: For my film tests I need total comparability. The test conditions have to be absolutely the same for all tested films, including new ones which hit the market. Therefore the same lens at the same aperture (f5.6, at which this lens offers the best performance) must be and is used.

That makes a lot of sense, I hadn't considered that!

Yes, there are some even better lenses on the market. I plan to publish some results in the future.

That should be interesting! Your figures are very useful as a reference, but I also kind of want to do it myself (on a tiny scale) for fun. It's also through such testing that you can see how close some more modest equipment can come to that and be certain that you're not wasting money on your Provia or whatever.

Aspheric surfaces offer the lens designer more freedom in design and more options. But they are also no guarantee for significantly better performance.
Very often they are used the reduce the number of needed elements in a lens to make it more compact.

Oh, is that usually the case? Interesting. I've usually gone by osmosis for what tends to perform better or not. I see that aspherical elements are becoming more common in lenses at a lower cost so I figured that must be improving what you can get far more accessibly.

Also, seeing that those ultra-optimized-for-one-wavelength photolithography optics use many, many elements makes me think that some of these otherwise too-complex designs are coming into the realm of possibility for mere mortals.

Evidence for that?

Admittedly, just comparing the lens data provided by each manufacturer:
Zeiss 15mm f/2.8 ZM
Laowa 15mm f/2 Zero-D LM

Though, on reviewing them, I originally thought the Laowa plots were wide open. And, while the 10lp/mm lines are super close, the Zeiss actually entirely crushed Laowa's 30lp/mm performance at even 40lp/mm. I had remembered it incorrectly. Still, the Laowa is incredibly impressive next to a lens like the Zeiss.
Zeiss:

Laowa:

Plus, I believe you've mentioned before that you admire Zeiss because they always do real-world tests to produce their plots rather than computing them.

Yes, both Voigtländer and Sigma with the Art series have introduced really outstanding lenses, which offer excellent additional value especially for film photographers.
The same is also valid for Zeiss with the Otus and Milvus lens lines. And the modern Leica lenses for the M cameras.

Yes, and it is encouraging to see! I think they might have been considered "off-brands" for a time. But my main interest was how some of them could reasonably compete with Leica and some of the high-end Zeiss lenses at far more affordable prices. I usually have just checked out what philipreeve says because there are some nice comparisons and shootouts.

Not only mirrorless: You will also find many modern Canon EF mount and Nikon F mount SLR lenses which are excellent and very significantly surpass their forerunners which were designed in the 60ies, 70ies and 80ies.

Just two examples:
- Nikon Nikkor AF-D 2/105 DC. Completely surpasses the excellent and very famous Nikkor 2,5/105 AI-S ( I have and use both lenses for many years). The 2/105 DC is one of the best lenses Nikon ever produced.
- Nikkor AF-S 1.8/24mm G ED. It blows the very popular 2.8/24 Nikkor "out of the water". The older 2.8/24 Nikkor has its "sweet spot" with optimal performance at f8. But the same level of resolution, sharpness and contrast I get at f8 with the older 2.8/24 I already get at f2.8 (!!) with the modern, current AF-S 1.8/24 Nikkor.
So a 3 stop advantage in optical performance. That is huge. Means you often could use ADOX HR-50 instead of HP5+ or Tri-X. And that makes really a huge difference!

I've heard as much! I was mainly concerned whether there was much being left on the floor with SLR lenses not having the advantage that mirrorless/rangefinder lenses do without the mirror in the way.

And yes, part of this is ensuring you're able to get good results at relatively wide apertures. f/8 is supposedly diffraction limited at 200lp/mm, which I believe means it extinguishes at that pitch.

Yes, that is correct.
My personal approach in 35mm photography: I love the versatility and all the numerous advantages this format has compared to medium format.
But I also love medium format quality, because I like to make bigger prints.
Therefore for me all is welcome which
- brings my 35mm results closer to the medium format quality level
- offer me (almost) medium format quality with 35mm.

Exactly! I hope Barnack would be proud of us... And I do find that kind of fun, the original goal of super high quality from the smallest camera, having been bettered decade by decade. You can put a teeny lens on a Leica, load up microfilm and get like 400mp of resolution almost reasonably easily.

Still, one thing about the format difference still remains besides resolution. I believe part of the "look" of larger formats is related to the "shape" of the depth of focus (I guess it's the CoC size vs object distance). Such as one being more S-curved and the other is more linear. A few other things too, but I haven't seen many analyses of those differences. I'll need to look into the further. But, otherwise, I think the "dream" has been well-fulfilled!

On a similar note here, one of Zeiss' lens lines promises "the medium format look" from full frame. Did they ever say how they intended to do that, and what traits they were trying to close the gap on? I believe what they were looking at there might answer some of the questions I have about what exact qualities separate the rendering of 35mm lenses vs MF and LF lenses.

And here the latest, much improved lenses for 35mm play an important role, because they
- offer significantly improved performance to older 35mm lens designs
- offer also improved performance compared to medium format lenses (where we are restricted in most cases to old(er) designs, and much slower lenses)
- offer much improved performance at wider apertures and open aperture.

With the older prime lens designs, you have to stop down 3-4 stops to get the optimal results. And performance at max. open aperture is relatively weak.
That is very different with most modern prime lenses: You often get very good and full usable performance at open aperture of f1.4 or f1.8. You then already get excellent performance only one stop stopped down, and perfect performance ("sweet spot") only 2-3 stops stopped down.
Example: My Zeiss Milvus Planar 1.4/85 ZF.2 offers already at f1.4 the same sharpness as my Nikkor 2.5/105 at f4 (!!).

Yes, it's great that we have these great lenses available to us, in some regards you don't have to consider it as much anymore. That does make searching for examples of great, old designs kind of fun, though. Like knowing certain Schneider Xenar lenses would be excellent (Kodachrome 25 guy was just using an old Retina, from what I recall), or which of the tiny Leica lenses made from the 20s to the 50s are actually rather good or great.

But the performance at wider apertures certainly allows us suffer far less from diffraction, even if at meager contrast, because a film like CMS 20 could capture it!

With the modern, significantly improved 35mm lenses I get a performance advantage of 1-3 stops, dependent on the specific lens.
Which also means that I often can use an ISO 100/21° film instead of ISO 200/24°.
Or ISO 100/21° instead of 400/27°.
Or even ISO 50/18° instead of 400/27°.
And the lower speed films offer significantly higher resolution, better sharpness and finer grain. They can be enlarged to bigger formats with excellent quality.

It seems stocks have in general found a happy spot to "settle" around in terms of speed, almost all of them lying from 50-800. Even advancements in efficiency (that 2e thing that Vision and then other negative films incorporated) was used to improve graininess but at the same speeds.

It doesn't seem to be exact, but the association between speed and grain size and resolution is neat. It made me think that merely having a film like CMS 20 be ISO 20 and achieve what it does would follow a similar trend. It doesn't seem to hold in all cases. Of course there are differences between color films and b&w. Also, things like certain intermediate motion picture films have effective speeds of 2 or so, yet they measure similarly to the camera films. But, when people coat plates at home with emulsions, how do those compare? I've seen rather little of people analyzing their collodion and dry plates.

Or, heck the daguerreotypes, which I figured would have some special quality in terms of resolution by being a uniform layer of silver instead of particles.

In medium format I have the disadvantage of slower lenses compared to 35mm.
My Zeiss 2/50 offers significantly better performance at f2.8 compared to the Mamiya Sekor C 2.8/80 at f2.8 (and the Sekor is a very good lens).
The Milvus Planar 1.4/85 offers at f2.8 much better performance compared to the Sekor 2.8/150 A (which belongs to best medium format lenses, by the way).
The Sigma Art 1.4/35 at f2.8 surpasses the (also excellent) Sekor C 2.8/55 at f2.8.

Something that might interest you is I once saw a flickr user adapt a Zeiss 85mm f/1.4 to a 645 body and it covered it quite well. I wonder how many designs could cover MF and are themselves excellent...

With the modern 35mm primes you can often use ISO 50/18° or ISO 100/21° films, when in medium format ISO 400/27° is needed. Equalizing the medium format advantage. Sometimes even surpassing MF.

With these modern 35mm format lenses and their excellent performance wide open and slightly stopped down usage of CMS 20 II and HR-50 / SCALA 50 becomes much more easy and comfortable.
Using HR-50 as a kind of "standard film" with these lenses is possible. And HR-50 in 35mm format with the extremely fine grain, excellent resolution and sharpness really offers you a medium format quality level.

Shooting your super high quality films with your super swanky lenses, not needing a whole MF or LF setup. Barnack's dream... I heard even some of the early (30s) Leica glass still remains rather good lol.

General rule is: The smaller the lens diameter, the higher the resolution. In general (there are some exceptions) medium format lenses have higher resolution than large format lenses, and lenses for 35mm format have higher resolution than medium format lenses.

My primes for 35mm format all surpass my medium format lenses of the equivalent focal length in resolution.

Perhaps the figures should be normalized for the image circle size then, for proper comparisons?

It is quite neat how this happens, though. Like I mentioned the Minox, but there's other lenses for some of the small format home movie cameras that are quite good. However, then it's a balancing act of whether you get quality or merely a "convenient" lens. Like whether it's on the level of the ok kit zoom you might get or if it's actually good for its size.

Focussing is really the bottleneck for high(est) resolution results (if you have a subject with no depth like a resolution test chart). And neither manual focussing aids lite split-image indicator or microprisms, nor the best AF systems are absolutally precise. You have a bit of variation from focussing process to focussing process. Therefore for my resolution test I use a kind of focus bracketing method: I make many shots (in case of film a whole 36exp. film), and each one is newly/freshly focussed. By that I obtain definitely at least several photos which are perfect in focus.

You test lenses too? I meant focusing on the aerial image to inspect what would otherwise be projected on the film.

That is realistic, as resolution of Kodachrome 25 has been indeed much higher than a 6000ppi scan.
The same is also valid for all ISO 100/21° E6 positive films of the last 20 years, and for Provia 400X. And for Delta 100, Acros, TMX, HR-50, CMS 20 II.....etc.

Correct. And with optical enlargement with the best enlarging lenses, and with slide projection with the best projection lenses you get the best results with film. Significantly higher resolution compared to even the best drum scanners, or camera scanning with the highest MP cams.

Thus my desire to shoot slide film and stare at it!!! They seem to have a really cool quality. And most of these slower B&W films!

Also RIP Portra 400X it seemed so cool...

Yes, existing film: It was Agfa Copex Rapid with a special developer for it.
Gigabitfilm was at first a cooperation of photo-engineer Heribert Schain from SPUR and D. Ludwig. The cooperation stopped because of differences about the developer quality: H. Schain wanted to improve the quality before market introduction, D. Ludwig wanted the market introduction at that time (early 2000s).
Schain was right in the end as the Gigabitfilm developer had weaknesses, and Gigabitfilm was no success in the market.

Heribert Schain of SPUR invested in further R&D and introduced his own improved SPUR developers for Agfa COPEX Rapid. The latest, current version is SPUR Dokuspeed SL-N. And Agfa Copex Rapid is still available as SPUR DSX film.

Wow I didn't know all this! It's surprising that multiple people have tried this in the past few decades. I'm curious how they all compare, is Adotech IV standing on the shoulders of giants, of POTA, H&W, the SPUR developer, the first 3 Adotech developers, to be the best low-contrast developer ever?

Can we use it to get 30 stops out of Portra? I asked in another thread about whether you can use one of these special b&w developers, with there being so many with all these different traits (contrast, acutance, grain solvents, physical development, etc etc), for color films. Apparently you theoretically could, but you'd need to fix the image and then rehalogenate it and THEN use the color developer. That's assuming the couplers don't suffer in some other way. I'm curious what results you could get!

Henning, thank you very much for answering my questions at such length! I always appreciated reading your contributions to various topics in this forum!

 

[Henning Serger]

Pyrocat-HD has several benefits:

1) It produces negatives with extremely fine grain and extremely high acutance, which is pretty unusual. For most film-developer combinations, those two qualities exist in opposition to each other.

Hello Scott,

there have been - and still are - also other developers which offer both very fine or extremely fine grain and excellent sharpness / acutance:
CG512, SPUR HRX, Perceptol 1+3, Ultrafin SF, JOBO Alpha.
But I agree that the combination of these two parameters is much rarer on the market compared to other parameter combinations.

Best regards,
Henning

 

[Sal Santamaura]

...there have been - and still are - also other developers which offer both very fine or extremely fine grain and excellent sharpness / acutance:...Perceptol 1+3...

That's been reported by others too. I've tried Perceptol 1+3 with both TMX and ACROS II. In neither case was the resulting negatives' acutance remotely close to what one gets from the same films in FX-39 II. I'll stick with ADOX's product.

 

[Henning Serger]

Oh, is that usually the case? Interesting.

Well, I've written often, not usually. That is a difference .

I see that aspherical elements are becoming more common in lenses at a lower cost so I figured that must be improving what you can get far more accessibly.

Yes, aspherical elements are used much more often, because the production processes have improved, and the costs have meanwhile become significantly lower.
As a lens designer you can use aspherical elements mainly for two purposes:
- reducing the needed number of elements in the lens to make it more compact
- improving the performance of the lens.

I have two very impressive examples here for both purposes:
1. For reducing number of elements: The Nikkor 3.5-4.5/28-70mm AF-D. It uses one aspherical element to reduce the number of elements to only 7 (!) elements, which is an extremely low number for a zoom lens. And this lens is really very compact. Nevertheless it is quite a solid performer.
2. For improving performance: The Nikkor AF-S 1.8/24G ED. It has two aspherical elements, which in combination with two ED elements offer an outstanding performance (especially also concerning the moderate price).

Plus, I believe you've mentioned before that you admire Zeiss because they always do real-world tests to produce their plots rather than computing them.

Yes, correct.
I am very cautious concerning the computer-generated MTF diagrams lens manufacturers publish. There is the danger of idealised diagrams because of marketing reasons.

Yes, and it is encouraging to see! I think they might have been considered "off-brands" for a time. But my main interest was how some of them could reasonably compete with Leica and some of the high-end Zeiss lenses at far more affordable prices. I usually have just checked out what philipreeve says because there are some nice comparisons and shootouts.

You may have a look also at
- https://opticallimits.com/
- https://www.lenstip.com/
- https://dustinabbott.net/category/lens-reviews/

Thus my desire to shoot slide film and stare at it!!! They seem to have a really cool quality.

Slide projection is just a league of its own! Absolutely unique and outstanding quality in colour brillance, resolution and three-dimensional impression: You feel like you just "back in the scene", back in the moment of releasing the shutter.
Excellent projectors with the best lenses can be bought on the used market for very low, attractive prices.

And most of these slower B&W films!

Try ADOX SCALA BW positive / reversal film as well. Amazing performance in projection!

Also RIP Portra 400X it seemed so cool...

Best ISO 400/27° colour film ever made. Fortunately I still have enough in my freezer........

Can we use it to get 30 stops out of Portra?

Why? For what purpose would you need that?
As Tim Parkin has demonstrated, about 16-18 stops are already possible. That is more you'll probably ever need.

Henning, thank you very much for answering my questions at such length! I always appreciated reading your contributions to various topics in this forum!

You're welcome.

Best regards,
Henning

 

[Henning Serger]

That's been reported by others too. I've tried Perceptol 1+3 with both TMX and ACROS II. In neither case was the resulting negatives' acutance remotely close to what one gets from the same films in FX-39 II. I'll stick with ADOX's product.

Hello Sal,

concerning Perceptol 1+3 I've got quite different and contradicting assessments: Some have been disappointed like you, and have expected better acutance, others have praised the results and were very satiesfied.
In pre-digital times we had a very good publication in Germany which was totally focussed on all photo laboratory work - Foto&Labor. They also did regularly developer tests. And Perceptol 1+3 has been one of their recommendations for the combination of very fine grain and very good sharpness.
When I used it (very long ago) I did no comparison tests at that time. I realized that I prefer liquid developers because of the much easier handling.
That is still generally the case for me. But at least the situation has been improved by ADOX with the CAPTURA technology. Which is really a real progress for powder photo chemicals.

From my results I can completely agree that FX-39 II offers very good acutance with many films.

Best regards,
Henning

 

[Andrew O'Neill]

I was under the impression that only 35mm will be available for a couple years, and no other formats. This is the first I heard (and from Adox); that they slitted 60mm for 120! This makes me very happy. I will have to keep my eyes and ears at the ready for when it comes available.

 

[Chuck1]

Agfa copex and adox cms ii are similar films or drastically different?
Anyone develop copex in adotech iv?

 

[dokko]

Agfa copex and adox cms ii are similar films or drastically different?

they areboth very fine grained high resolution films, but still quite different.
Copex has very fine grain (finer than TMX), but CMS 20 II is significantly finer still.
Copex also has higher ISO and is a bit easier to get normal contrast with.

both are great films and sometimes I prefer Copex because the texture can add to the image.

Anyone develop copex in adotech iv?

good question. I haven't (always used SPUR Dokuspeed SL-N), I would expect @Henning has though, so hopefully he can add some info.

 

[Crysist]

Well, I've written often, not usually. That is a difference .

Ah, whoops!

Yes, aspherical elements are used much more often, because the production processes have improved, and the costs have meanwhile become significantly lower.
As a lens designer you can use aspherical elements mainly for two purposes:
- reducing the needed number of elements in the lens to make it more compact
- improving the performance of the lens.

I have two very impressive examples here for both purposes:
1. For reducing number of elements: The Nikkor 3.5-4.5/28-70mm AF-D. It uses one aspherical element to reduce the number of elements to only 7 (!) elements, which is an extremely low number for a zoom lens. And this lens is really very compact. Nevertheless it is quite a solid performer.
2. For improving performance: The Nikkor AF-S 1.8/24G ED. It has two aspherical elements, which in combination with two ED elements offer an outstanding performance (especially also concerning the moderate price).

I see, that's a good point. It's fun to compare those drastically different examples, or even more extreme cases. The new Nikkor Noct is an example of weight and elements galore.

But then isn't it often the case that 1 and 2 are the same? Maybe more elements is needed for any zoom lens, but for primes, if you're using aspherical elements to cut down on the number of elements, it means you would have had a pretty complex all-spherical design. What much is there to do when adding so many more elements to the classic designs that have proven quite good than to make small or large step ups in performance? Such that you need 2 or 3 or more aspherical elements.

Heck, it actually seems the fundamental unit is the number of aspherical surfaces. That's quite a bit more to consider.

Yay I'm doing well at Henning Trivia Night! xD

I am very cautious concerning the computer-generated MTF diagrams lens manufacturers publish. There is the danger of idealised diagrams because of marketing reasons.

Yeah, I try not to pay too much attention, but I still like to reference them to see if they're in nice ballparks. Then I go and take everyone's comparisons to see whether that level of performance is even worth it next to some other lenses that are older or less expensive. If some lens hits "extreme" levels of sharpness and then I see it in a shootout against some earlier glass or maybe a Voigtlander lens that performs relatively similar, the cost and weight savings are really worth considering.

But thankfully, like I said before, we can get modern glass that's less expensive AND high performing compared to many older lenses that had even earned a reputation for being super good. Some old lenses' concept of "incredibly sharp" can fall apart under modern standards for performance. And when we throw microfilm at them lol.

Regardless, high-end telephotos seem to uniformly do extremely well. Is there anything that makes them less suited for benchmarking? Other than space?

You may have a look also at
- https://opticallimits.com/
- https://www.lenstip.com/
- https://dustinabbott.net/category/lens-reviews/

Thanks for these!

I forgot that another guy named Marco Cavina has these wonderfully in-depth articles on his site but now writes for Noc Sensei. And Ken Rockwell does great reviews given his own engineering background. I like reviewers who have an engineering focus, it makes them methodical and I appreciate their reviews!
https://dustinabbott.net/category/lens-reviews/

Slide projection is just a league of its own! Absolutely unique and outstanding quality in colour brillance, resolution and three-dimensional impression: You feel like you just "back in the scene", back in the moment of releasing the shutter.
Excellent projectors with the best lenses can be bought on the used market for very low, attractive prices.

*starry eyed*

I've seen a few of my Mom's old Kodachrome slides and, even without projecting them, they had a brilliant quality to them. I wanted to eat up the blue in them. And I've heard, that one Leica projector and lens combination seem super attractive.

I suppose, in a way, it's not entirely unique to it. I think I'm among many people who when we see a projected film it inspires a similar feeling. Of course, it's sourced from negative stock, but even creating a print seems to imbue some of those same characteristics and they seem to manifest in a unique way. Just consider how many people like the look of scanned prints compared to some home video releases for films, despite being inaccurate as a scanned source relative to the original elements. Materials intended for projection have a cool look even when you intentionally don't project them!

Try ADOX SCALA BW positive / reversal film as well. Amazing performance in projection!

Ooo, that sounds fun! Do BW positives have a similar jump in brilliance compared to negatives? I mean, you can't view negatives exactly anyway, but do they?

Also, what does reversing a BW film require? I know they come with kits made for it, but what do they consist of that's different from a normal kit (besides bleach)? You can bleach the silver and develop the "negative's negative", but do you need to pair it with a high contrast developer to make it slide-y?

Best ISO 400/27° colour film ever made. Fortunately I still have enough in my freezer........

How much do Ektachrome and Provia 100 withstand pushing? Though I imagine the Provia 400 could handle some push processing thus blowing those out of the water as it has a two stop lead...

Why? For what purpose would you need that?
As Tim Parkin has demonstrated, about 16-18 stops are already possible. That is more you'll probably ever need.

Science! Fun! Bragging rights!!

And merely to see what it can do. CMS, like HR-50, etc has a similar effect where under a normal contrast developer, a large portion of the exposure range develops to the base + fog density. With special low contrast developers, much of the range that had ended up in base+fog is now in the straight line portion. I wonder how much this reasonably works until.

Also, having mentioned slide film, I wonder if you'd get an interesting result by trying to make lower-contrast slides. I know the operating principle for projection is having a DEEP black level to block the projection light and display an inky black level. Another aspect that's admired is their strikingly high contrast. But has anyone ever done that anyway lol?

---

@ADOX Fotoimpex So, is a film like CMS 20 a difficult formula or no? If CMS 20 is gone, is it "rip too bad" or do you consider it a trivial film to make?

I've read some of the emulsion-making materials on here and it's fun to consider all the variables at play. Emulsion thickness, granularity, variance of grain size, grain shape, layers, etc and what attributes they all contribute.

 

[Mark J]

But then isn't it often the case that 1 and 2 are the same? Maybe more elements is needed for any zoom lens, but for primes, if you're using aspherical elements to cut down on the number of elements, it means you would have had a pretty complex all-spherical design. What much is there to do when adding so many more elements to the classic designs that have proven quite good than to make small or large step ups in performance? Such that you need 2 or 3 or more aspherical elements.

Heck, it actually seems the fundamental unit is the number of aspherical surfaces. That's quite a bit more to consider.


I forgot that another guy named Marco Cavina has these wonderfully in-depth articles on his site but now writes for Noc Sensei. And Ken Rockwell does great reviews given his own engineering background. I like reviewers who have an engineering focus, it makes them methodical and I appreciate their reviews!
https://dustinabbott.net/category/lens-reviews/

Aspherics are useful both in primes and zooms. The advantages of aspherics on the 'paper' design are clear , but in practice there are some trade-offs. If the aspheres are moulded ( for low cost), then the limit on surface accuracy is not as good as with spherical surfaces. For instance, a moulded glass element may be difficult to get at less than 3 fringes surface accuracy ( 1.5 waves of light ) . However it is relatively easy to get a spherical surface down to 0.5 to 1.0 fringe accuracy.
Hence if you add too many aspheric surfaces to a design, you can lose performance. Aspherics are typically the source of 'onion ring bokeh' , due to a concentric ripple error left in the manaufacture of the mould and hence the lens. There can also be problems from stop-down focus shift if an aspheric surface near the stop has a significant peak or hollow near the centre.

Equally as important in the last 15 years had been the more extensive use of anomalous-dispersion materials in all lenses, but particularly in wide angles and zooms. Unfortunately, whereas aspherics can cut the number of elements in a design, using anomalous-dispersion materials tends to add lens elements !

Marco is an excellent person with an extraordinary collection of articles and patents and camera gear. His blog has some fascinating articles about optics and the history of various marques. He's also written a number of books that are reference works for collectors. I've been happy to supply him with optical analysis for the Noc Sense site, in the last 3 years.

 

[cptrios]

Slightly off-topic here, but does anyone have any idea what the shelf-life is like on an open bottle of HR-Dev? I'd like to pick one up now to try it with some HR-50, but if it works out my 'real' usage of the combo will come around December. It'd be nice not to have to buy another bottle. Thankfully it's not too expensive!

 

[Donald Qualls]

If you use marbles to fill up the air space or blanket the bottle with argon or butane the storage life of an open bottle is nearly that of a never-opened one. Six months shouldn't be a big deal.