Condenser/Diffuser Hybrids

[ic-racer]

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?

Condensers and light pipes don't absorb much light energy as heat. Diffusers do absorb quite a bit of light energy as heat,

 

[xkaes]

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.

The Beseler-Agfa Colorhead incorporated C-M-Y filters that were dialed in (0-199) -- just like with the quartz colorheads -- but it used an incandescent 250w projector bulb -- and a standard condenser. How does that not provide "actual colored light"?

And whether the color is provided by passing/removing white light through built-in, easily adjustable dichroic filters or manually slide-in CC filters, they are accomplishing the exact same thing in exactly the same way.

 

[DREW WILEY]

Sundowner - most enlarger heads don't give even illumination over the full range of potential applications. Ideally, you'd need a whole set of convex diffusers to offset the illumination falloff factor of different lenses, even at different f-stops. Beseler probably made a calculation concerning what a typical lens would represent at the most likely f-stops. Longer than "normal" focal length enlarging lenses have much less falloff than normal and wider than normal lenses, just like with camera lenses. And in most cases, the falloff is worst at maximum aperture, then steadily improves a by a couple stops down, where typical enlarging lenses enter their best performance zone.

Beseler chose a thick moulded white acrylic element rather than having each one ground to specification, which would have been a tedious chore to say the least. But there are higher transmission ways to do it too.

With so many of these things, engineers come up with interesting ideas, but then these innovations turn out half-baked when all the compromises of cost and outsourcing get factored in. That certainly isn't unique to Beseler or even any one industry. It drove me crazy when I interacted with power tool designers prior to retirement. Really clever ideas got watered down to uselessness in order to meet the price point parameters set by the marketing monkeys, whereas the kind of professionals who could really use those kinds of tools if they reliably worked would have happily paid a premium price. I got so fed up that I focussed more and more on German engineering rather than the usual suspects. Contrary to the typical marketing philosophy, the more expensive the equipment was, far more of it sold, and it was much more profitable to everyone, a win-win - ourselves as the sellers, and the end-users too because their work became dramatically more efficient.

The analogy being - how much actual prototyping and thorough personal testing was actually done by some of those later Beseler head designers. Nowhere near enough in my opinion. I hope that has improved, but based on sheer experience, I remain a bit skeptical. End of rant.

 

[Sundowner]

Condensers and light pipes don't absorb much light energy as heat. Diffusers do absorb quite a bit of light energy as heat,

That makes sense. Light that's not being transmitted must remain somewhere, and in some given state; it can't just vanish, so it must manifest itself, in this case as heat.

The Beseler-Agfa Colorhead incorporated C-M-Y filters that were dialed in (0-199) -- just like with the quartz colorheads -- but it used an incandescent 250w projector bulb -- and a standard condenser. How does that not provide "actual colored light"?

I think we're miscommunicating, here. When I was talking about an "actual" colorhead I was referencing the dial-operated, tri-color light sources that use either an internal/integral system of subtractive filtration or discreet additive spectra in order to generate a specific and controllable output that relies upon no external filtration to produce the desired result.

And whether the color is provided by passing/removing white light through built-in, easily adjustable dichroic filters or manually slide-in CC filters, they are accomplishing the exact same thing in exactly the same way.

They are, yes, but at some point the term "colorhead" becomes overly broad and consequently murky; thus; I've limited my usage of it to the above definition. Technically, any visible light source is a "color" head regardless of output, simply because visible light in any denomination is composed of visible-color wavelength, and any filtration of said output becomes exactly the same process across all platforms, much as you described. But at that point the term becomes entirely redundant, because it could refer to anything...so there's always a degree of personal interpretation that's brought to bear in situations such as this, and especially so when the subject doesn't offer a solid consensus. This seems to be the case, here, and I apologize if I've misunderstood you or misinterpreted the standard terminology. Hopefully, my clarification helps to elucidate my definitions.

Sundowner - most enlarger heads don't give even illumination over the full range of potential applications. Ideally, you'd need a whole set of convex diffusers to offset the illumination falloff factor of different lenses, even at different f-stops. Beseler probably made a calculation concerning what a typical lens would represent at the most likely f-stops. Longer than "normal" focal length enlarging lenses have much less falloff than normal and wider than normal lenses, just like with camera lenses. And in most cases, the falloff is worst at maximum aperture, then steadily improves a by a couple stops down, where typical enlarging lenses enter their best performance zone.

Makes sense. I usually use a longer focal length on my enlargers than is necessary, and I stop down into the 11 to 16 zone; this may account for why I usually don't see any kind of falloff in my prints.

Beseler chose a thick moulded white acrylic element rather than having each one ground to specification, which would have been a tedious chore to say the least. But there are higher transmission ways to do it too.

That also makes sense.

With so many of these things, engineers come up with interesting ideas, but then these innovations turn out half-baked when all the compromises of cost and outsourcing get factored in. That certainly isn't unique to Beseler or even any one industry. It drove me crazy when I interacted with power tool designers prior to retirement. Really clever ideas got watered down to uselessness in order to meet the price point parameters set by the marketing monkeys, whereas the kind of professionals who could really use those kinds of tools if they reliably worked would have happily paid a premium price. I got so fed up that I focussed more and more on German engineering rather than the usual suspects. Contrary to the typical marketing philosophy, the more expensive the equipment was, far more of it sold, and it was much more profitable to everyone, a win-win - ourselves as the sellers, and the end-users too because their work became dramatically more efficient.

That makes the most sense so far; I've been in that kind of situation in my own career, and am happily no longer dealing with that kind of over-watering. It's basically the "sell a bunch of decent" instead of "sell a few good ones" and there's a logic to that viewpoint, of a sort. This being said, I agree with you: from having had to professionally use tools for a living, I bought the absolute best ones that I could afford and spent far less money in the end than the people that went with the better-known, locally-available brands. That's not to say that there is no use or case for an inexpensive tool, but there's never a good use for a bad tool.

The analogy being - how much actual prototyping and thorough personal testing was actually done by some of those later Beseler head designers. Nowhere near enough in my opinion. I hope that has improved, but based on sheer experience, I remain a bit skeptical. End of rant.

One of the things that I like best about reading the R&D threads that people post on this forum is the amount of testing that they do to create something that works for their process; I feel like more of that needs to be done on the part of manufacturers in general. Sure, there's no way to build something that works for everyone, but I've found that the larger pitfalls can usually be avoided with a modicum of testing.

So, this being the case, I need to start making some early-stage decisions about what I'm going to do for my enlarger head. At this point I don't know that I need to be overly concerned with using condensers, so it may be both easier and better to create a purely diffused head and fine-tune it for my process.

 

[xkaes]

When I was talking about an "actual" colorhead I was referencing the dial-operated, tri-color light sources that use either an internal/integral system of subtractive filtration or discreet additive spectra in order to generate a specific and controllable output that relies upon no external filtration to produce the desired result.

Take a look at the picture of the Beseler-Agfa Colorhead. You will see three dials -- one for each color filtration level (C-Y-M) that you dial in. It works just light the quartz colorheads except it uses an incandescent bulb instead.

 

[Sundowner]

Take a look at the picture of the Beseler-Agfa Colorhead. You will see three dials -- one for each color filtration level (C-Y-M) that you dial in. It works just light the quartz colorheads except it uses an incandescent bulb instead.

I have looked at that model, and that's basically what I was talking about: it's a dial-operated, three-color light source that uses selective/integral filtration. So, yeah, that kind of system is what I mean when I originally used the term "colorhead".

 

[xkaes]

Whether your fingers turn a dial to insert filtration into the light path, or your fingers directly insert filters into the light path, optically it is exactly the same thing.

And the filters don't really care whether the light source is incandescent, quartz, halogen, tungsten, LED, sunlight, etc.

 

[Sundowner]

Whether your fingers turn a dial to insert filtration into the light path, or your fingers directly insert filters into the light path, optically it is exactly the same thing.

And the filters don't really care whether the light source is incandescent, quartz, halogen, tungsten, LED, sunlight, etc.

So, is there a light source that's not a color head, by that definition?

On the original topic: it seems that unless there's an actual point source - like, a bare bulb filament - and absolutely no diffusion elements in the mix at all, then technically most enlarger systems with lenses or refractory elements are actually hybrid condenser/diffuser systems of one ilk or another. That doesn't really seem to be the way we're using the term, but that's okay; it's clear that "condenser" is use-limited to heads that predominantly feature lenses to collimate their light, regardless of what other features may be present. Likewise, it's clear that "diffuser" is use-limited to heads that feature heavy diffusion and dissipation elements, with the end goal being significantly different in both cases.

Thought: perhaps the practical deployment of each type is more the basis for differentiation and typology than their respective optical arrangements.

Furthermore, it seems that hybrid heads - or heads in general - are kind of an all-bets-are-off situation. I think it would be fair to say that there's no proper or universally-correct way of introducing diffusing elements into the light path; they can be placed pretty much wherever, with varying effects.

 

[ic-racer]

You should check out Post Exposure by Ctein (available somewhere to download pdf). Most of it is the usual stuff but he does experiments to demonstrate the principles.

 

[Sundowner]

You should check out Post Exposure by Ctein (available somewhere to download pdf). Most of it is the usual stuff but he does experiments to demonstrate the principles.

First or second edition? Both seem to be available.

 

[DREW WILEY]

His own setup was a very basic Beseler 4x5 unit plus a lot of duct tape holding things down sufficiently enough for small dye transfer printing purposes. He might have been using an adapted oversized cold light head; I don't remember. The sheets of Pan Matrix DT film would have been exposed through supplemental gel filters using "white" light in relation to color neg originals. Now he just does inkjet printing; the necessary DT materials have dried up.

 

[xkaes]

So, is there a light source that's not a color head, by that definition?

There are lots of enlarger heads that don't allow you to change the color -- IN THE HEAD. Besesler's bare-bones condensers, for example, do not have a drawer/slot where you can insert color filters -- but you can always place filters under the lens, which does the same thing. Cold light heads, as far as I know, don't allow any filtration either. So any enlarger can be a "color" enlarger, but not all enlarger heads are color heads.

 

[Sundowner]

Cold light heads, as far as I know, don't allow any filtration either.

Are you saying that there is no inherent physical provision for a filter in cold light heads, or that the light output of the lamp does not work with filters?

So any enlarger can be a "color" enlarger, but not all enlarger heads are color heads.

I'm not sure that I understand the division, here, but that's okay because I think I get the overall point.

 

[DREW WILEY]

It's a somewhat misleading assessment. Prior to modern colorheads, filter drawers on tungsten bulb beehive enlargers would accept Y,M,and C sheet filters of various cc gradations which enabled color printing, if clumsily. Or R,G,&B sheet filters could be used sequentially (not simultaneously) to allow color separation work for sake of processes like dye transfer printing.

But cold light heads are basically bent fluorescent tubes, and the specific phosphors determine the output color; but this is never a true "blackbody" continuous spectrum light source like a halogen bulb or sunlight. So it would be unwise to select a cold light for color printing per se. Certain types like the V54 Aristo output blue-green light specifically for sake of improved VC paper results; and one can trim out either the blue or green component by using the opposite filter, green versus blue, or else just use the light "as is" for more ordinary results, but not realistically for actual color printing.

Aristo once did offer a special more balanced white cold light choice for sake of color printing; but I doubt it ever caught on, especially since tungsten-halogen colorheads were a far better choice at the time.

My own V54 8x10 cold light is the high-output 12X12 variety, so I installed it with the ability to have an overhead neutral density filter in place if necessary to slow exposures down. It was intended to do enlargements with supplementary contrast masks in register with the original 8x10 shots, as well as easily print with a deep blue 47B filter in place, or else even a deep green 58 or 68 for sake of split printing, with a lot of reserve lumen capacity. I use good quality glass filters on the lens itself. There is no evident diminishment in the visual quality like would be the case if polyester filters or polyester "lighting gel" sheet material were used beneath the lens.

 

[koraks]

On the original topic: it seems that unless there's an actual point source - like, a bare bulb filament - and absolutely no diffusion elements in the mix at all, then technically most enlarger systems with lenses or refractory elements are actually hybrid condenser/diffuser systems of one ilk or another. That doesn't really seem to be the way we're using the term

Sort of. We generally apply the term 'condenser' to a system that's either a diffuser/condenser hybrid, or a point source system. We use the term 'point source' if it's literally that, and it's fairly rare in day-to-day amateur darkroom use.

Thought: perhaps the practical deployment of each type is more the basis for differentiation and typology than their respective optical arrangements.

I think the typology is based on the presence of one or more condensing lenses. In that sense, it seems reasonably conceptually clear, although it leaves the distinction between a point source and a non-point source system somewhat...diffuse.

I think it would be fair to say that there's no proper or universally-correct way of introducing diffusing elements into the light path; they can be placed pretty much wherever, with varying effects.

Try it out and see. You'll notice that there actually are wrong places to put them.

Are you saying that there is no inherent physical provision for a filter in cold light heads, or that the light output of the lamp does not work with filters?

Depends on what kind of 'cold head' you're talking about. Some are basically white-light fluorescents. These could be filtered, since the light itself is spectrally diverse/broad (but maybe not perfectly continuous). Some cold lights are phosphor-based green or blue tubes, usually one of both arranged together in a single plane, for VC work. You can't filter out what's not there, so evidently, filtration with these would only make sort of/kind of sense if you would use both tubes at the same time and then filter out green or blue to a degree. And the term 'cold head' is today also applied to LED-based light sources, which again can be either broad- or narrow-spectrum emitters. Does that help? I guess not. As you're finding out, perhaps we're not really dealing with typologies here, but rather with somewhat informal taxonomies.

 

[DREW WILEY]

The V54 Aristo is a single tube set, with blue-green output, and NOT two separate grids overlapping, one blue and the other green, like the Zone VI cold light, for example. Its own unfiltered "white light" is therefore not white at all, but is very well balanced by itself for what was once classified as Grade 3 paper. For split printing, supplemental B vs G, or M vs Y, filters are necessary. Graded papers were of course mainly blue sensitive, while ordinary tungsten sources are rather warm yellowish until modified via filtration.

 

[Sundowner]

It's a somewhat misleading assessment. Prior to modern colorheads, filter drawers on tungsten bulb beehive enlargers would accept Y,M,and C sheet filters of various cc gradations which enabled color printing, if clumsily. Or R,G,&B sheet filters could be used sequentially (not simultaneously) to allow color separation work for sake of processes like dye transfer printing.

I didn't know that...but I also don't know anything about color printing, so that's not surprising.

But cold light heads are basically bent fluorescent tubes, and the specific phosphors determine the output color; but this is never a true "blackbody" continuous spectrum light source like a halogen bulb or sunlight. So it would be unwise to select a cold light for color printing per se. Certain types like the V54 Aristo output blue-green light specifically for sake of improved VC paper results; and one can trim out either the blue or green component by using the opposite filter, green versus blue, or else just use the light "as is" for more ordinary results, but not realistically for actual color printing.

My normal procedure with a V54 bulb is to split print with Multigrade filters; but I'd like to get rid of them. It's not that they don't work, it's that I can't ever remember to change them between hard/soft exposures.

My own V54 8x10 cold light is the high-output 12X12 variety, so I installed it with the ability to have an overhead neutral density filter in place if necessary to slow exposures down. It was intended to do enlargements with supplementary contrast masks in register with the original 8x10 shots, as well as easily print with a deep blue 47B filter in place, or else even a deep green 58 or 68 for sake of split printing, with a lot of reserve lumen capacity. I use good quality glass filters on the lens itself. There is no evident diminishment in the visual quality like would be the case if polyester filters or polyester "lighting gel" sheet material were used beneath the lens.

I would be okay with glass filters, I think...but again: I have to do my part. And that's where I always fail. I really enjoy split-printing... I'm just not very good at it.

 

[Sundowner]

I think the typology is based on the presence of one or more condensing lenses. In that sense, it seems reasonably conceptually clear, although it leaves the distinction between a point source and a non-point source system somewhat...diffuse.

That's well said.

Try it out and see. You'll notice that there actually are wrong places to put them.

I should do that, honestly. Usually I don't think of anything as inherently wrong unless it's a physically unworkable or non-functional method, so I need to see how the various arrangements play together.

Does that help? I guess not. As you're finding out, perhaps we're not really dealing with typologies here, but rather with somewhat informal taxonomies.

I think that's the crux of the issue: informal taxonomy within a field that's changed, still-changing, and always somewhat open to interpretation.

 

[Sundowner]

The V54 Aristo is a single tube set, with blue-green output, and NOT two separate grids overlapping, one blue and the other green, like the Zone VI cold light, for example. Its own unfiltered "white light" is therefore not white at all, but is very well balanced by itself for what was once classified as Grade 3 paper. For split printing, supplemental B vs G, or M vs Y, filters are necessary. Graded papers were of course mainly blue sensitive, while ordinary tungsten sources are rather warm yellowish until modified via filtration.

A friend of mine uses the Zone VI with the double-tube setup, and his results are downright luminous...but I suspect that result has more to do with him being a masterful printer than it does the light source of his enlarger. I think he could likely do just as well with a broken lens and a surplus DDR flashlight.

Also, I find the most interesting things when I sit down and read through old books.

Pictured: I'm always so late to the party.

 

[xkaes]

What this points out is that enlarger light sources exist on a continuum from very sharp to very diffuse -- in some ways similar to an artist's various paint brushes. And while most photographers might stick to only one light source, many have several heads and use them as needed.

 

[Sundowner]

What this points out is that enlarger light sources exist on a continuum from very sharp to very diffuse -- in some ways similar to an artist's various paint brushes. And while most photographers might stick to only one light source, many have several heads and use them as needed.

In my old darkroom, I had twin 23C chassis side-by-side. One was a standard condenser, and the other was Aristo-fied, with the housing up above the filter drawer. I often went back and forth between them, looking for specific results...or just making comparisons.

 

[koraks]

Pictured: I'm always so late to the party.

It's not you, though. The funny thing is that if you do a web search on the distinction between condenser and diffuser enlargers, you find a whole lot of stuff that turns out to be about confusion enlargers instead. The clearest explanation I had read previously was, I think, in a Durst enlarger user manual. Go figure.

 

[xkaes]

In my old darkroom, I had twin 23C chassis side-by-side. One was a standard condenser, and the other was Aristo-fied, with the housing up above the filter drawer. I often went back and forth between them, looking for specific results...or just making comparisons.

I'm not the only one that has two enlargers for this reason. For me, one has a condenser on it (most of the time), and the other a diffusion head (most of the time), so it's easy to switch from one to the other depending on the negative. I'm lucky to have enough space -- it wasn't always the case.

SOME people even have MORE than TWO enlargers -- can you image that?

 

[Sundowner]

It's not you, though. The funny thing is that if you do a web search on the distinction between condenser and diffuser enlargers, you find a whole lot of stuff that turns out to be about confusion enlargers instead. The clearest explanation I had read previously was, I think, in a Durst enlarger user manual. Go figure.

That's what I'm calling them from now on.

I'm not the only one that has two enlargers for this reason. For me, one has a condenser on it (most of the time), and the other a diffusion head (most of the time), so it's easy to switch from one to the other depending on the negative. I'm lucky to have enough space -- it wasn't always the case.

Yeah, I don't have that space anymore, myself. In my old darkroom I had room for the two, and also an area for a third one, which I used for parts and repairs.

SOME people even have MORE than TWO enlargers -- can you image that?

Nope, can't imagine that. Not at all. Two is definitely the most I can imagine. All numbers past two do not exist. In no way, shape, or form do I possess more than two enlargers, most of which do not work. It's just the two 23s, and that's all. Just those two.

 

[mshchem]

That's what I'm calling them from now on.



Yeah, I don't have that space anymore, myself. In my old darkroom I had room for the two, and also an area for a third one, which I used for parts and repairs.



Nope, can't imagine that. Not at all. Two is definitely the most I can imagine. All numbers past two do not exist. In no way, shape, or form do I possess more than two enlargers, most of which do not work. It's just the two 23s, and that's all. Just those two.

I have an 8x10 Zone VI type 2 VC cold light enlarger, a 5x7 Zone VI VC cold light enlarger, a Beseler 45MXT with the 45 Universal VC controller, and finally another Beseler 45MXT with the 45 Universal head setup with the color controller. The Zone VI enlargers have a 10 foot stainless sink, the Beseler units have a wide 7 foot sink.

Everything is closed loop so adjusting contrast doesn't (dramatically) change exposure time. Everything is diffusion, easy enough to insert condensers on the Beseler units if needed.

All these things are closed loop additive (like the Heiland LED light sources) .

Still pretty hard to beat a reliable subtractive head with a incandescent source and dichroic (or acetate) filters. Just not as handy. I've been putting together my darkroom since I was in high school. The only enlarger I bought new was in high school. Everything else was scrounged