Condenser/Diffuser Hybrids

[Sundowner]

Did a search; didn't come up with much...and that tracks because I've seen exactly one such setup in my life.

My question is this: how are these things normally arranged, in terms of components? The only one I've seen was really just a condenser head with a piece of diffusion plastic directly over the negative stage...so I don't know if that's typical, or unusual. I assume the idea is to create the intensity of the collimated light source, but to tone down the artifacts that tend to show up.

The reason I'm asking is...well, pure curiosity, actually. I have a bunch of parts sitting around right now and I'm working on a few other projects, so thinking on this kind of thing in my downtime is helpful. And generally speaking, I don't know much of anything...so it's helpful to learn. So yeah: chime in if you know something.

 

[ic-racer]

One can diffuse the light before or after the condensers.

Usually, as you mentioned, the diffusion material would be between the condensers and the negative. That is how Durst allows it on some condenser heads with the optional diffusion material. This is probably what you want. In this case the characteristics of condensers are lost as efficiency is lost (light becomes dimmer). Negatives will print less contrasty and may be less likely to show dust.

The other way (diffusion before the condensers) is frequenty done with a light pipe that mixes colored lights and projects to a diffusion screen that is imaged by the condensers (instead of the dome of a light bulb). In this case characteristics the condenser system remain. That is, the efficeincy is great and negatives will print more contrasty and show dust.

Two examples would be the Vivitar 'Light Pipe' enlarger and the Philips 150. The Philips also has a light pipe, in this case before the mirror, but it is kept a secret in the advertizing.

 

[ic-racer]

'Secret' light pipe of the Philips PCS 150.

 

[xkaes]

Most of Beseler's color diffusion heads were designed to be used with the condenser removed -- but with the Dichro 45, Dichro 45S, and Universal 45, the condenser can be retained with an adapter: Beseler describes it as "a different look". The diffusion head basically becomes the light bulb for the condenser.

http://www.subclub.org/fujinon/enlargers.htm

 

[ic-racer]

BTW, these light pipes are different from the fiber optic light pipe Marty Forscher used for Polaroid backs on 35mm film cameras.

 

[ic-racer]

Most of Beseler's color diffusion heads were designed to be used with the condenser removed -- but with the Dichro 45, Dichro 45S, and Universal 45, the condenser can be retained with an adapter: Beseler describes it as "a different look". The diffusion head basically becomes the light bulb for the condenser.

http://www.subclub.org/fujinon/enlargers.htm

Yes, that is a good one too. Thanks for poinitng it out.

 

[Sundowner]

Okay, some of that is starting to make sense...but since I'm a relatively low-watt bulb in and of myself, I need some science explained to me:

How does the positioning of the condenser in relation to the diffusion material impact efficiency from the perspective of the negative, and therefore the print?

It seems that if any given amount of light traverses a given distance with a constant amount of interruptions along the way - i.e. the condenser lenses and the diffusion plate - then there should be no change in the energy that's transmitted, no matter where those interruptions lie or in what order they're arranged...but if that's not what actually takes place then what seems correct must be wrong. So: would it be more correct to assume that placing the condenser adjacent to the source is effectively changing the amount of light that's actually being transmitted to the remainder of the system?

Also, how would a diffused light source impact this arrangement?

 

[DREW WILEY]

Whatever works, works. You could hypothetically double-diffuse it with two spaced apart diffusion sheets to get more even illumination.
You could alter the light source and remove any condensers entirely. Or you could just change out the entire head. There are all kinds of methods.

I don't know why a Phillips enlarger diagram showed up. That's an outlier or arcane odd duck, so to speak. And as far as I know, the only enlarger which ever used fiber optic bundles to direct the exposing light was the rare and expensive Salthill model.

What model and format size of enlarger are you actually intending to alter? That would be nice to know if you want specific answers.
I've done all kinds of conversions; but the most direct approach is to simply remove the condenser head and replace it with a modern colorhead or other diffusion source.

 

[MattKing]

Okay, some of that is starting to make sense...but since I'm a relatively low-watt bulb in and of myself, I need some science explained to me:

How does the positioning of the condenser in relation to the diffusion material impact efficiency from the perspective of the negative, and therefore the print?

It seems that if any given amount of light traverses a given distance with a constant amount of interruptions along the way - i.e. the condenser lenses and the diffusion plate - then there should be no change in the energy that's transmitted, no matter where those interruptions lie or in what order they're arranged...but if that's not what actually takes place then what seems correct must be wrong. So: would it be more correct to assume that placing the condenser adjacent to the source is effectively changing the amount of light that's actually being transmitted to the remainder of the system?

Also, how would a diffused light source impact this arrangement?

Adjustments can result in meaningful portions of the light either not reaching the negative or reaching the negative at an angle that doesn't result in that light being imaged through the lens on to the paper. In other words, effectively becoming non-imaging flare that doesn't even add fog to the image.

 

[Sundowner]

Whatever works, works. You could hypothetically double-diffuse it with two spaced apart diffusion sheets to get more even illumination.
You could alter the light source and remove any condensers entirely. Or you could just change out the entire head. There are all kinds of methods.

Yeah, it seems like there's a lot that can be done, but without me really understanding the nuances of how various configurations differ - which is fixable - it's hard for me to make educated guesses.

What model and format size of enlarger are you actually intending to alter? That would be nice to know if you want specific answers.

Right now I'm futzing around with a garden variety Beseler 45.

I've done all kinds of conversions; but the most direct approach is to simply remove the condenser head and replace it with a modern colorhead or other diffusion source.

I have a couple of Aristo heads laying around; that's my only ready-made solution.

Adjustments can result in meaningful portions of the light either not reaching the negative or reaching the negative at an angle that doesn't result in that light being imaged through the lens on to the paper. In other words, effectively becoming non-imaging flare that doesn't even add fog to the image.

Interesting...

I'll have to think on that part in bold most specifically. This is where I tend to rely on diagrams, so when I'm just imagineering my way through it...well, who knows where I'll end up.

 

[MattKing]

For clarity, a well designed enlarger light source system limits and controls any such poorly used illumination.
But there always will be some.
And finally, a condenser enlarger that uses a frosted bulb is itself a Condenser/Diffuser hybrid.
The frosting on the bulb is itself a diffuser.

 

[DREW WILEY]

Hard to say about any old Aristo cold light head. Depends on their condition; and they need to be distinctly oversized for even illumination.
I use an oversized Aristo VC54 blue-green cold light on one of my 8x10 enlargers; but that's a different story.

The Beseler 4x5 chassis should be easily convertible to one of their colorheads, which are quite convenient for VC printing too. But If you want to stick with the old beehive condenser head, I suggest you get some scrap pieces of 1/16 inch thick "Sign White" acrylic plastic, and cut them down to the appropriate size to experiment with between your light bulb and the negative stage itself. That's the cheapest way to get started, and might be all you need. Or the plastics shop could cut them to size for you for a modest fee. "Sign White" is more translucent than regular white Plexiglas or Acrylite of the same thickness.

Don't let this kind of project intimidate you. Try to have fun with it. It's hard to go wrong with a few sheets of diffuser plastic; but it might take some experimentation to arrive at the best effect.

 

[Sundowner]

For clarity, a well designed enlarger light source system limits and controls any such poorly used illumination.
But there always will be some.

That makes sense.

And finally, a condenser enlarger that uses a frosted bulb is itself a Condenser/Diffuser hybrid.
The frosting on the bulb is itself a diffuser.

That makes even more sense. Thank you.

Hard to say about any old Aristo cold light head. Depends on their condition; and they need to be distinctly oversized for even illumination.

The two in consideration are both standard-sized, which is a condition that never really caused me any problems on the smaller 23 chassis...but I wasn't printing out at the limits of the system with those enlargers: 6x6 was about the normal limit for me. The 45 is a different story; I'm bothering with it in the first place in order to be capable of 4x5 enlargements.

I use an oversized Aristo VC54 blue-green cold light on one of my 8x10 enlargers; but that's a different story.

One of mine is a V54, and the other is a W45. I wasn't planning on using the latter; I mostly have that one because it was a very good price.

The Beseler 4x5 chassis should be easily convertible to one of their colorheads, which are quite convenient for VC printing too. But If you want to stick with the old beehive condenser head, I suggest you get some scrap pieces of 1/16 inch thick "Sign White" acrylic plastic, and cut them down to the appropriate size to experiment with between your light bulb and the negative stage itself. That's the cheapest way to get started, and might be all you need. Or the plastics shop could cut them to size for you for a modest fee. "Sign White" is more translucent than regular white Plexiglas or Acrylite of the same thickness.

I know the Beseler chassis get a bad rap from some, but I rather like them. They are simple designs with inexpensive parts, they work well, and they're reasonably durable despite their shortcomings: I'm not sure if they're the T-34 of enlargers, but they often feel like it.

I have the old skool condenser, yes, and I'm playing around with it. I also have the Aristos, and I thought about picking up one of the old halogen or quartz heads - I'm not sure which one used what - and literally gutting it, and then building a big LED panel for the interior. The main thing that I want to work on is easy above-the-negative contrast filtration; I split-print almost everything with a #00/#5 combination, and I like the results...so that's kind of the big goal. I also happen to like the look of the diffuser on my 23, so I'm heading that direction as well. How I get there...no idea yet.

Also, I think the Sign White acrylic is what I got when I replaced the diffuser on my 23 head. I had forgotten that until you mentioned it; thank you!

Don't let this kind of project intimidate you. Try to have fun with it. It's hard to go wrong with a few sheets of diffuser plastic; but it might take some experimentation to arrive at the best effect.

I like this kind of stuff; it helps me learn. I tend to make lots of expensive mistakes, but I usually come out slightly ahead in the end. Or I at least break even. Or I just break stuff.

 

[mshchem]

Most of Beseler's color diffusion heads were designed to be used with the condenser removed -- but with the Dichro 45, Dichro 45S, and Universal 45, the condenser can be retained with an adapter: Beseler describes it as "a different look". The diffusion head basically becomes the light bulb for the condenser.

http://www.subclub.org/fujinon/enlargers.htm

I tried this several years ago. Basically the adapter for using condenser with the colorhead did what could be expected, added contrast. I still have the adapter somewhere. Looks cool.

 

[Sundowner]

I tried this several years ago. Basically the adapter for using condenser with the colorhead did what could be expected, added contrast. I still have the adapter somewhere. Looks cool.

I'd like to see that, if you happen to find it.

So, it looks like all of the later colorheads were quartz-powered. I don't really think I have a ton of desire to go that route, but yeah...the housing might be good for some kind of diffuser array over a condenser. Maybe I could look for a broken one, if I go that route; right now it's all just theoretical. I'm hoping to keep my exposures short but I really don't want to give up the diffuse light source; that's been critical for many of my prints.

Late-night pondering: what about a high-wattage LED in place of the standard bulb, well above the condenser stack, and then some sign white acrylic? Sandwich a filter drawer in there somewhere and I would be good to go... assuming that the LED is getting the output I need for the Ilford filters that I use.

 

[mshchem]

Beseler used a white diffusion disk, acrylic I presume. The quartz halogen lamp is off to the side, fan cooled light passes through dichroic filters, enters a chamber, 35mm, 6x7, 4x5 (I always use the 4x5) then finally passes through the acrylic.

 

[koraks]

Late-night pondering: what about a high-wattage LED in place of the standard bulb, well above the condenser stack, and then some sign white acrylic? Sandwich a filter drawer in there somewhere and I would be good to go... assuming that the LED is getting the output I need for the Ilford filters that I use.

Yeah, should work. I use something conceptually similar from a light-path viewpoint. I don't use filters, but instead a controllable array of R, G and B LEDs, so I dial in whatever filtration I need digitally. However, you can indeed use a white LED source, optionally add a diffusion panel if the light path in your enlarger requires it, and use old-fashioned filters. Several people have replaced their tungsten/halogen light bulbs for LED ones and have reported good results.

 

[Sundowner]

Yeah, should work. I use something conceptually similar from a light-path viewpoint. I don't use filters, but instead a controllable array of R, G and B LEDs, so I dial in whatever filtration I need digitally.

I've thought about something along those lines: basically a switchable blue/green array that effectively mimics my #00/#5 filters. That way, I wouldn't even have to remember to change filters or add in the complexity of a drawer: I could just flip a switch in a convenient location and instantly get my soft/hard filtration. And sure, add some red for composition. I actually had a thought about removing the upper bellows entirely and using that area as the diffusion head, but if I want to utilize a condenser system I won't be able to do that.

However, you can indeed use a white LED source, optionally add a diffusion panel if the light path in your enlarger requires it, and use old-fashioned filters. Several people have replaced their tungsten/halogen light bulbs for LED ones and have reported good results.

I've been reading a bit on that. Definitely a simple and direct way to test things out, but it wouldn't give me the supreme laziness inherent to a blue/green array. But I don't completely know how to build that array, yet; I need to learn more.

 

[koraks]

If all you'll do is B&W and split grade with just blue and green, then a simple switch would be the easiest. I also use the enlarger for color and when I print B&W, I rarely split-grade print, so my use case relies on adjustable filtration. This necessitates a more involved implementation.

I use a Durst 138 which has the swappable condensers in neat little (uhm) modules, that can slide in and out of the chassis. I was once gifted a (broken) cold light module that slid into the lower condenser socket, which sits right above the negative. I still have to build a light source into this one; it would result in something very similar to the Heiland system. https://heilandelectronic.de/led_kaltlicht/lang:en However, I've always preferred to stick with the original condenser setup for reasons of efficiency and print qualities. Although I admit that either argument is very debatable and it's probably in my head more so than on the paper. However, this is what I went with and what I've stuck with so far, with very little need to 'upgrade' to a diffusion light source. Building the latter would be more a case of "because I can" than anything else.

A diffusor system is easier to implement, though, in terms of getting even illumination. If you have an enlarger in which you can fit a regular household white LED bulb, then that's of course the easiest approach. But if you have a hybrid diffuser/condenser system (such as what I'm using), then it can take some experimentation to get even illumination especially when using an array of emitters. Milky plexiglass, carboard and duct tape are your friends in figuring out the appropriate distance between light source and diffuser, and diffuser and condenser stack.

 

[Sundowner]

If all you'll do is B&W and split grade with just blue and green, then a simple switch would be the easiest.

Yep, that's pretty much all I do. The only other filter that's used is the 2.5, and I use that for quarter-sheet compositional enlargement, or for larger proofing. Given equivalent blue and green intensity, however, I could probably just turn both of them on and get a 2.5, and maybe adjust the current to dim things a bit.

I'll have to think on that.

I use a Durst 138 which has the swappable condensers in neat little (uhm) modules, that can slide in and out of the chassis. I was once gifted a (broken) cold light module that slid into the lower condenser socket, which sits right above the negative. I still have to build a light source into this one; it would result in something very similar to the Heiland system. https://heilandelectronic.de/led_kaltlicht/lang:en However, I've always preferred to stick with the original condenser setup for reasons of efficiency and print qualities. Although I admit that either argument is very debatable and it's probably in my head more so than on the paper. However, this is what I went with and what I've stuck with so far, with very little need to 'upgrade' to a diffusion light source. Building the latter would be more a case of "because I can" than anything else.

Now that it's been explained and I've spent a few hours trying to wrap my head around it, the old adages about condensers are starting to make more sense. It does seem like they help to make good use of whatever light is being generated.

A diffusor system is easier to implement, though, in terms of getting even illumination. If you have an enlarger in which you can fit a regular household white LED bulb, then that's of course the easiest approach

Yep, I do have one of those. Standard Beseler head with a 211 - maybe a 212 - bulb in it.

But if you have a hybrid diffuser/condenser system (such as what I'm using), then it can take some experimentation to get even illumination especially when using an array of emitters. Milky plexiglass, carboard and duct tape are your friends in figuring out the appropriate distance between light source and diffuser, and diffuser and condenser stack.

Check my logic, here. Given that:

1. The condenser stack is there to make efficient use of the light by way of collimation, and...
2. Diffusion sources, by default, will always reduce the amount of light being transmitted...

...it would be very possible to overcome the loss of condenser efficiency simply by increasing the output of the light source. Light placement in relation to the negative would be another matter entirely, but given sufficient distance and testing, it's a solvable problem.

Does that seem correct?

Also, here's the one other question that's cropped up: in what way does the hybrid setup actually alter the look and feel of the prints? Is it just a middle-of-the-road situation with qualities of both, or does it create something entirely new?

 

[koraks]

Given equivalent blue and green intensity, however, I could probably just turn both of them on and get a 2.5, and maybe adjust the current to dim things a bit.

You'll likely have to dim the blue light back a bit to get to grade 2-2.5. So ensure you've got some way to balance blue & green if you also want to do a single grade print somewhere in the middle of the range.

Does that seem correct?

Yes, correct.

Is it just a middle-of-the-road situation with qualities of both, or does it create something entirely new?

It's middle of the road between a proper point source enlarger (super efficient, very sharp, contrasty, but lots of issues with dust, scratches etc., very finicky w.r.t. light path setup) and diffusion (easy to work with, no fuss, dust & scratches don't show up easily, but inefficient w.r.t. power use, less conrasty and less 'snap' to the prints). It's a compromise that negates most of the tricky bits of a proper condenser/point source setup (which is quite rare because of its drawbacks). Whether you'll see the difference in real life prints...hard to tell. If the differnce would be substantial, all enlargers would employ the same system. Given that they don't, it's apparently a tie.

 

[snusmumriken]

I don't think such a hybrid enlarger needs to be complicated. The light pipe on Philips enlargers is only on those with a colour head, and possibly only later ones at that. I have the PCS130, which just has an opal bulb as a moderately diffuse light source. The exact position of the bulb was factory-set. There is nothing between the bulb and the mirror, and only a heat filter between the mirror and the condenser. I have had it for about 35 years and am totally happy with it (for b/w printing, and given a good lens). In the absence of a colour head I use under-lens filters. For anything critical the filter drawer is an option, but honestly I can't tell any difference in the result.

 

[xkaes]

I'd like to see that, if you happen to find it.

So, it looks like all of the later colorheads were quartz-powered. I don't really think I have a ton of desire to go that route, but yeah...the housing might be good for some kind of diffuser array over a condenser. Maybe I could look for a broken one, if I go that route; right now it's all just theoretical. I'm hoping to keep my exposures short but I really don't want to give up the diffuse light source; that's been critical for many of my prints.

Late-night pondering: what about a high-wattage LED in place of the standard bulb, well above the condenser stack, and then some sign white acrylic? Sandwich a filter drawer in there somewhere and I would be good to go... assuming that the LED is getting the output I need for the Ilford filters that I use.

Two points. First, if you check out the link I provided above, you'll see that Beseler offered colorheads that used incandescent light bulbs and LEDs, as well.

As to the Beseler Condensesr Light Chamber (#8294) for it's Quartz colorheads, it consists of two parts. In order to use it, you need a condenser head and an appropriate diffusion colorhead.

With the condenser head in place, the condenser light source on top is removed, and a 3" high, metal collar is attached in its place. It's basically just a spacer. Then the colorhead is placed on top of this collar with the Condenser Light Chamber installed inside -- instead of one of the standard light chambers (Beseler made three -- one for 4x5, one for 6x7, one for 35mm).

The extension collar and the Condenser Light Chamber basically mimic a P211 light bulb on top of the condenser (which Matt has accurately pointed out is really a diffuse light source) with the colorhead throwing colored light into the mix. You get the same exact effect if you simply slide CC filters into the filter holder of the standard Beseler condenser -- Beseler actually referred to their condenser heads as "Bescolor" because you could use them for making color prints with CC filters.

 

[DREW WILEY]

For split printing with a V54 cold light all you need are good quality deep blue and deep green glass filters below the lens. More practical than a filter drawer.

Over the decades, Beseler has offered quite a range of different colorheads; and then the company itself changed ownership during part of that cycle. Some of us were extremely displeased with their discontinuity in servicing previous units. Hopefully that has changed by now; but it is somewhat a risk when multiple new innovations come out, and as each gets abandoned for something allegedly better, the former product becomes an unwanted stepdaughter in terms of servicing or parts. That's why I favor equipment in my own darkroom which I am personally able to maintain and repair if needed. Otherwise, one might get stranded on a desert island.

With some of their colorheads they supplied a thick convex moulded white acrylic diffuser at the bottom of the tube. That is for sake of trying to get more even illumination at the negative stage plane if full 4x5 film is involved. But it also absorbs quite a bit of light. There are better workaround options to that; but I don't want to make the conversation too complicated unless the actual need arises.

 

[Sundowner]

In the absence of a colour head I use under-lens filters. For anything critical the filter drawer is an option, but honestly I can't tell any difference in the result.

I've had bad results from going under the lens; that's been 90% of the reason that I've been adamant about using the filter drawer. The other 10% is because I just like making things, and making a few dedicated holders for the three filters that I use is a fun project.

To expand on my first sentence: even while using new, clean, pristine filters, I kept feeling like the prints made from them while under the lens felt a bit off. I could never explain it fully, but something was different. So, we did a blind test: my partner picked ten different images from my negative catalog, and I made two of what I would consider to be an acceptable print from each. One print was from a filter in the drawer, and the other was from the below-lens filter. She marked the sheets so she would know which was which, and after they were processed I tried to identify them. I got seven of the ten correct, and the other three I just said "I'm not sure." A few weeks later we repeated the test with a just-opened set of filters, and I got eight of the ten. I have no answer for how that happened - could be literal blind luck - but I stopped using below-lens filters at that point, entirely.

Two points. First, if you check out the link I provided above, you'll see that Beseler offered colorheads that used incandescent light bulbs and LEDs, as well.

I did; that's a good read. When I was referencing the color heads, I was specifically talking about the ones that introduced some kind of actual colored light; the incandescent ones weren't really in that category, to me. As I said: I have a garden-variety condenser head, and I know it's a "color" head per Beseler, but it really kind of just isn't.

As to the Beseler Condensesr Light Chamber...

That explanation helps; thank you.

The extension collar and the Condenser Light Chamber basically mimic a P211 light bulb on top of the condenser (which Matt has accurately pointed out is really a diffuse light source) with the colorhead throwing colored light into the mix. You get the same exact effect if you simply slide CC filters into the filter holder of the standard Beseler condenser -- Beseler actually referred to their condenser heads as "Bescolor" because you could use them for making color prints with CC filters.

Yep, that's the not-colorhead that I have.

For split printing with a V54 cold light all you need are good quality deep blue and deep green glass filters below the lens. More practical than a filter drawer.

No arguments, I just evidently suck at doing that kind of thing. And there's something about objects being in the light path between the lens and the paper that just inherently bothers me. I have no idea why that is, but it's definitely there. Probably just a personality defect.

Over the decades, Beseler has offered quite a range of different colorheads; and then the company itself changed ownership during part of that cycle. Some of us were extremely displeased with their discontinuity in servicing previous units. Hopefully that has changed by now; but it is somewhat a risk when multiple new innovations come out, and as each gets abandoned for something allegedly better, the former product becomes an unwanted stepdaughter in terms of servicing or parts.

I've seen that happen so many times over the years, with a variety of products. Irritating at best, and unsustainable at worst.

That's why I favor equipment in my own darkroom which I am personally able to maintain and repair if needed. Otherwise, one might get stranded on a desert island.

Yep, same here...and I like desert islands, but I also like being able to leave them on my own schedule. I don't want to end up with things that I can't service or can't repair.

With some of their colorheads they supplied a thick convex moulded white acrylic diffuser at the bottom of the tube. That is for sake of trying to get more even illumination at the negative stage plane if full 4x5 film is involved. But it also absorbs quite a bit of light. There are better workaround options to that; but I don't want to make the conversation too complicated unless the actual need arises.

I've seen that kind of diffuser before, but I've not yet uncovered the theory behind it. I get that it's an attempt to prevent uneven illumination, but I'm not sure why it's that uneven. I've also seen one of those that's designed for use with Aristo lamps; I don't get that, either...but by all means, go into it. This entire conversation is about understanding the subtleties about how condensers and diffusers play together, so, yeah: go there if you wish.