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View Full Version : 12x16" enlarger - which lens ?

plaubel
4-May-2016, 07:59
Dear folks,

I am slightly planning how to place, and how to use my 12x16" enlarger.
I played around with some math,and concerning the height of my room and the decision vertical/horizontal position of the enlarger, now I wish to bring in my 305mm Schneider G-Claron.
Alternatively, I have to buy a 355mm G-Claron, but then I would loose important space.

Does the 305mm cover , could I expect some distortions,fall off - what do you think?
Concerning my enlarging ratios here, 3:1 or 4:1, I have a good feeling, but less experience.

Thanks,
Ritchie

Luis-F-S
4-May-2016, 08:39
305 G-Claron should be fine. I can look up image circles when I get home next week.

ic-racer
4-May-2016, 09:11
The PDF file I have shows theoretical image circles for the G-Claron at f22 305mm as follows (goal = 508mm):

1:1 = 820mm
1:3 = 547mm
Infinity focus = 411.5mm

I would not expect any observable distortions within the manufacturer's stated limits of coverage above.
There is always light falloff due to physics.

The question is how big are you enlarging?

Realize at 1:1 your negative to paper distance is calculated at 1220mm

plaubel
4-May-2016, 10:50
Both, thanks for answering my question.

I stated my enlarging factor as 3:1 or 4:1; this will increase the image circle.
Theoretically, the 305 G-Claron woul be fine, yes, but how does it come out in practice?
It's more than a short lens for 12x16"...

At ratio 4:1, the height of my next dark room ( 300cm ) would be fine, either for 305mm or 355mm lenses.
But the 305mm just lays around.

So probably, I will built a vertical enlarger.

ic-racer
4-May-2016, 12:34
So probably, I will built a vertical enlarger.

Should be just enough room.

As a practical example:

In VERTICAL configuration the Durst L1840 will make a 4X print with a 300mm lens with the table all the way down and the head all the way up (281cm). But 4X is the maximum that can be done without projecting on the wall for that enlarger. (the extra negative size for your negative does not affect the distances involved with a 300mm lens).

plaubel
4-May-2016, 13:50
(the extra negative size for your negative does not affect the distances involved with a 300mm lens).

I agree; the math behind needs the focal length and the ratio of negative and enlargement, not the size of the negative.
But different negative sizes give different ratios, if you want the same size of the print, so there is some relevance, too.

Drew Wiley
4-May-2016, 15:37
Gosh. Edge performance and falloff issues would be a lot better with something like a 480 Apo Nikkor. It's not like taking an in-camera neg for 1:1 contact printing
usage. 305 works fine for 8x10 enlargements. Bigger than that ...??

ic-racer
4-May-2016, 19:31
I agree; the math behind needs the focal length and the ratio of negative and enlargement, not the size of the negative.
But different negative sizes give different ratios, if you want the same size of the print, so there is some relevance, too.

Exactly, and for your negative at 4x, I suspect you chose that because the 48" short dimension will fit on a roll of paper.

Since the reference for coverage has been disputed, you may need some trial and error unless your lens comes with this same document in the box. Anyway, here is the file. Since it is a composite, the 305 specs are the fifth row from the top. This may not be clear, so I pointed it out.

150470

Steve Goldstein
5-May-2016, 09:26
As you can see in the cutaway view this datasheet is for the earlier Dagor-style G-Clarons. The later Plasmat-derived G-Clarons will have slightly different coverage but I don't know if it will be significant enough to limit you at the corners of 12x16.

plaubel
5-May-2016, 12:16
Interesting conversation!
Covering is given; edge performance and falloff issues must be discussed, thanks, Drew.

Trial and error /testing different lenses is difficult to me.
I first have to build the enlarger out of my parts ( mainly the complete head), but before building and choosing horizontal/vertical position, I better have to know about the quality of my lenses.
There would be no fun in building a vertical machine and then quantifying my 305 G-Claron as not so fine, without any given space for bigger lenses then.

I could throw in a 480mm or a 520mm Apo Ronar, yes, but my ratios then will only come in horizontal position.
This would be my second solution.

Hopefully we can clear if the 305 G-Claron as an enlarging lens here is in it's own quality range or not, or if it would be a big advantage using a 355mm G-Claron.
Or a bigger Apo Ronar...
I am not interested in prints with bad edges, I really wish to reach good to best quality.

Thanks,
Ritchie

bob carnie
5-May-2016, 12:47
Could you post a picture of this beast 12 x16 wow.

Drew Wiley
5-May-2016, 13:22
Let me reiterate that there seems to be some confusion about what might be realistic as a ULF taking lens versus quality enlarging. Two different subjects! You
can get away with things on a 1:1 contact print that tend to be visually annoying in an enlargement. And I'd rather have a 4-element Apo Nikkor on an enlarger than anything G-Claron. The Apo Nikkor will out-perform any standard enlarging lens, while a GC is basically on par with better older ones like Componons. But yeah, going longer focal length equates to horizontal projection unless you have a very high ceiling, and ladder to go with it. And in any event, you'll have to grind a diffuser to match the specific lens you do choose. Going relatively wide-angle per film format means you will not only have to use either a very thick-at-center or substantial edge and corner burning, ALONG WITH one or two smaller lens stops to get even coverage and reasonably clean corners. I just ran a whole battery of analogous with various enlarging lenses for 8x10 film. I didn't learn anything new, but certainly confirmed it. Printing speed is significantly affected by
going wide angle. And 305 is extremely wide for 12x16.

ic-racer
5-May-2016, 16:04
A 'who to believe' situation might arise if you did not have the lens, however, since you have the 305 lens and a 12x16 camera, you can easily check the coverage before you build the enlarger. Take a picture of a wall with a 48" x 64" outline just filling the image area. Put a piece of newspaper with print at each corner and in the center. Check the negative with a loupe. The answer is yours.

Luis-F-S
5-May-2016, 16:07
Could you post a picture of this beast 12 x16 wow.

Drew Wiley
5-May-2016, 16:19
It's not that simple! Most enlarger lenses are used around f/8 to f/11. To get adequate performance in this case, the lens might have to be stopped way the hell down, both for the sake of corner resolution and a manageable level of illumination evenness. That means either slow printing times, or else you have to have a very bright light source (doable, but potentially hot, and harsh on utility bills, depending). Commercially, big enlargers like this once operated with very expensive xenon flash tubes. I've built a couple of high-output large format enlargers, so kinda know what to anticipate. Too bad Aristo still isn't in business. Back in the day
they could have made a custom high-ouput cold light.

Luis-F-S
5-May-2016, 21:20
A 'who to believe' situation might arise if you did not have the lens, however, since you have the 305 lens and a 12x16 camera, you can easily check the coverage before you build the enlarger.

What, you thought we were all going to agree on this? You own the lens, use it! You don't like the results buy a different lens!

plaubel
6-May-2016, 01:46
As told months ago in another thread, I bought parts of a Hohlux Elektron, mainly the complete head, a big fan, and the vacuum board.
This board seems to weigh 100 Kg, it has a lentgh of 100 to 120cm, and I don't believe that I will use it.
Imagine the construction, I have to build for moving this weight...
The complete head himself weighs something around 75 Kg, maybe some more, with 8 x 1000 Watts Xenon bulbs and a speed shutter included..

The bulbs should give warm feed in my apartment right over the dark room, but I am thinking about another solution.
Here again is the picture of the original and complete monster of 840 Kg :

150498

Standing face to face, it felt more like starting a Space Shuttle than starting an enlargement.
So sad that I was unable to lift and rescue the complete piece...

Good input here, thanks again.
Checking the coverage as described is a good idea, but I have Drews words in mind, too.
This check says not much about needed lightsource/intension for comfortably printing and the other aspects.
But it would give a first idea...

Drew, I believe in your words, but I also believe that a repro lens could give a fine enlarger lens, if not then by turning the lens with 180 degrees ( retro).
Simply physics, in my opinion, but I may be wrong, you have the experience, not me.

Luis, unfortunately I can't play around as said before.
"Buy another (longer) lens" in worst case means "build another enlarger" :-)

Ritchie

ic-racer
6-May-2016, 07:09
I bought parts of a Hohlux Elektron

You have to post pictures !!

bob carnie
6-May-2016, 07:53
Wow Wow Wow- that is an incredible looking beautiful monster. try to keep it as original as you can that baseboard is gold.

As told months ago in another thread, I bought parts of a Hohlux Elektron, mainly the complete head, a big fan, and the vacuum board.
This board seems to weigh 100 Kg, it has a lentgh of 100 to 120cm, and I don't believe that I will use it.
Imagine the construction, I have to build for moving this weight...
The complete head himself weighs something around 75 Kg, maybe some more, with 8 x 1000 Watts Xenon bulbs and a speed shutter included..

The bulbs should give warm feed in my apartment right over the dark room, but I am thinking about another solution.
Here again is the picture of the original and complete monster of 840 Kg :

150498

Standing face to face, it felt more like starting a Space Shuttle than starting an enlargement.
So sad that I was unable to lift and rescue the complete piece...

Good input here, thanks again.
Checking the coverage as described is a good idea, but I have Drews words in mind, too.
This check says not much about needed lightsource/intension for comfortably printing and the other aspects.
But it would give a first idea...

Drew, I believe in your words, but I also believe that a repro lens could give a fine enlarger lens, if not then by turning the lens with 180 degrees ( retro).
Simply physics, in my opinion, but I may be wrong, you have the experience, not me.

Luis, unfortunately I can't play around as said before.
"Buy another (longer) lens" in worst case means "build another enlarger" :-)

Ritchie

Drew Wiley
6-May-2016, 09:58
Process lenses can be superb, even better than conventional enlarger lenses. I enlarge with them all the time. But my concern is with the short focal length. Looks
like you have the firepower to handle a very thick diffuser (thick at center, thin at edges) to help the evenness of the projection. But if possible, I'd be looking to
see if anyone has any of those xenon tubes left over at a discount, cause they can be horrifically expensive to replace. Then there is the heat issue. You need a
pretty agressive pull fan system with heat-resistant ducting. But back to the bulbs... are these designed to be operable in a 90-degree position, if you project
horizontally? Not all are. Sure looks like a fun project, however. My biggest enlarger is fourteen feet tall and has a vac easel so solid I can stand on it without
deflecting it. Just the easel itself must weigh around 400 lbs. My Durst 8x10 unit looks tiny beside it. But my poor fingers... gosh, I'm paying the price with tendonitis from all that heavy moving!

plaubel
6-May-2016, 12:10
You have to post pictures !!

Sorry, the parts are well stored; no chance to bring more pictures the next weeks - or months.
Do you know a garage totally full with things, and the important thing is behind left, on the floor ?
After a move I first filled the room, and now I have to clear the room, step by step;
after this, I may start to build the new dark room off this room...

""Looks
like you have the firepower to handle a very thick diffuser""

Drew, the Holux hasn't any diffuser; each 4 of my 8 Xenon bulbs are crossed ( horizontal/vertical in principle ); for me it looks that the 8 bulbs give even - and more than bright - light.
But I'm not lucky with this bulbs; they are expensive, they are very dangerous, and they are hungry for voltage.
Maybe I will try them, but I'm not sure.

Maybe the 305mm isn't the best solution, so I can go with a longer lens, too.
355mm also will be fine, and using some math will clear the possibilities of longer lenses in horizontal projection...
A lot of maybees at this point...

Heat isn't a problem, I grabbed the original fan.
But your idea that the transportation of the heat may not function with vertical position is a very good point.

Bob, the baseboard is heavy like plumbum :-)
I can't imagine how to install it moveable without a ton of more steel.
Maybe I will construct a non moveable board, we will see.

Drew Wiley
6-May-2016, 12:43
Evenness due to bulb configuration doesn't solve your hypothetical problem. As you go wider in lens angle, you get more illumination falloff, just like in taking lenses. But it's also relative to the working aperture. So once everything is set up, you make a relatively high-contrast (hard grade) test print, just to see how
well the system work, before you customize a diffuser. No diffuser and you nuke your negs with UV. These things were originally made for special graphics work, not general photo enlarging. And it is hard to know how well the bulbs survived the move. They should have been removed first. Then the weight. Hope you're on a firm slab. For ventilation, I'd recommend an exterior-mounted pull fan. Pulling air is a far more efficient method than pushing it; and you've get the fan noise isolated that way too. Oh boy, this sounds like fun stuff! You'll have some dicey moments getting everything ironed out; but what a machine!

bob carnie
6-May-2016, 12:49
Drew this looks like a photo enlarger not graphic arts.. do you know what applications it would have been used for other than photo.

It has a vacuum easel and I have never heard of this unit. it puts my 11 x14 Devere 515 to shame.

Drew Wiley
6-May-2016, 13:15
It's quite similar to the big Italian Pawo's. They were used with screens, generally for projection separations needing very high luminance rich in UV. There would
be no conventional photographic application for these. Big muscle large format heads would have been designed horizontal instead to begin with, for mural work.
You could take one of these to print directly onto Azo or maybe even platinum, provided you find a relatively rare lens optimized for UV transmission, along with
analogous enlarger glass. All the gasketing with have to be high-temp aero silicone. That has actually been done a few times; but that concept is self-defeating due to the significant skin cancer and eyesight hazards of open UV. I wonder if anyone here has seen the granddaddy of all UV enlargers - the carbon arc Fresson
unit, for that direct-carbon process?

bob carnie
6-May-2016, 13:22
Ok - I missed the part about UV light source... I wonder if someone with a good head on their shoulders could retrofit the exposing head with suitable lights for regular enlarging.

Drew Wiley
6-May-2016, 13:47
Sure, the heads can always be reconfigured. Durst built these kind of rigs too, but only up to 8x10, yet similarly vertical for modest enlargement. I don't recall the exact type of plates that were exposed with these, versus regular stat cameras, which used film obviously. But the specialty outfit I dealt with way back when I had a hot (literally) color mural enlarger still sold the xenon tubes; so these were still apparently in limited technical usage around here, maybe early circuit panel
prototyping with resists. I remember one of these enlargers rotting for sale forever in a basement, because the dealer wouldn't compromise a cent of the price of the dinosaur. I've seen several 11x14's up for sale in recent years.

Bob Salomon
6-May-2016, 15:23
Sure, the heads can always be reconfigured. Durst built these kind of rigs too, but only up to 8x10, yet similarly vertical for modest enlargement. I don't recall the exact type of plates that were exposed with these, versus regular stat cameras, which used film obviously. But the specialty outfit I dealt with way back when I had a hot (literally) color mural enlarger still sold the xenon tubes; so these were still apparently in limited technical usage around here, maybe early circuit panel
prototyping with resists. I remember one of these enlargers rotting for sale forever in a basement, because the dealer wouldn't compromise a cent of the price of the dinosaur. I've seen several 11x14's up for sale in recent years.

Afraid that is not quite true. Back when I was a RecTec technician in the USAF in the early 60s we regularly printed 9x9" aerial negs on both Durst and Homerich enlargers. And those were not custom military enlarger's. They were common, off the shelf units. Big shelves though.

Drew Wiley
6-May-2016, 16:09
Bob, you obviously know your stuff; but so do I. I have some components from the same outfit that did Durst's custom aerial neg enlargers, and have even seen
the guts for the custom colorheads. We're talking early 90's technology here, not 60's, actually the last of the true industrial Durst production, never for sale to the public. The NSA bought them and installed them in a facility where ZERO digital technology was allowed. They wanted a double-blind system that couldn't be fraudulently manipulated. The other advantage was the intuitive ability to assess real aerial film images, versus specialized analysts. In other words, rapid assessments can be made with big true-color enlargements, like a spotting scope, and then afterwards specific details can be homed in on via satellite or drone imaging. Astronomers have an analogous problem. They rely on smaller scopes used by amateurs to first discover a comet or asteroid, and then tell the big observatory pros where to look with the fancy gear. Of course, decisions are ultimately made by politicians and other big egos who might or might not respect
the facts, but that doesn't discount the technological advantages themselves. I have no idea if these units are still in use. If they are, nobody is supposed to know about them anyway. I do simply because of my own analogous design needs, asking around.

Drew Wiley
6-May-2016, 16:20
Oh, forgot. That basement unit I was talking about was specifically tricolor, sequential that is, for three separate color separations via high-output xenon onto a
pin-registered easel. Gotta be a different use than film, more like some kind of sensitized plate. Much gnarlier tubes than for photographic mural use. When I first
contemplated taming one of these, I was working on a water-cooled colorhead. But I already had a colorhead that would punch a 30x40 Ciba with a .90 supplementary mask in a matter of seconds. The damn thing shot my utility bill through the roof. So I went back and rethought the whole problem, and ended up
with something unique, with superb color, which actually runs cool - a much better design than Durst's, in fact, but also damn schizophrenic electronically. I'm
doing psychoanalysis on it again! That why I did recently install a parallel conventional Durst 8x10 color unit, as a backup.

Bob Salomon
6-May-2016, 16:50
Bob, you obviously know your stuff; but so do I. I have some components from the same outfit that did Durst's custom aerial neg enlargers, and have even seen
the guts for the custom colorheads. We're talking early 90's technology here, not 60's, actually the last of the true industrial Durst production, never for sale to the public. The NSA bought them and installed them in a facility where ZERO digital technology was allowed. They wanted a double-blind system that couldn't be fraudulently manipulated. The other advantage was the intuitive ability to assess real aerial film images, versus specialized analysts. In other words, rapid assessments can be made with big true-color enlargements, like a spotting scope, and then afterwards specific details can be homed in on via satellite or drone imaging. Astronomers have an analogous problem. They rely on smaller scopes used by amateurs to first discover a comet or asteroid, and then tell the big observatory pros where to look with the fancy gear. Of course, decisions are ultimately made by politicians and other big egos who might or might not respect
the facts, but that doesn't discount the technological advantages themselves. I have no idea if these units are still in use. If they are, nobody is supposed to know about them anyway. I do simply because of my own analogous design needs, asking around.

Drew, I was printing Cuban Crises images as well as images from integration when we flew the Univ. of Alabama and the Univ. of Mississippi during the early 60s with those enlarger's. Not in the 90s.

Drew Wiley
9-May-2016, 11:50
Those were the days, Bob. 60's and 70's... We'll never see precision machining like that again - enlargers, microscopes, even my Norma camera.

jack_hui
10-May-2016, 00:10
My god!!! It makes all 8x10 enlarger looks like a kindergarten's toy!!!