12x16" enlarger - which lens ?

[plaubel]

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]

305 G-Claron should be fine. I can look up image circles when I get home next week.

[ic-racer]

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]

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]

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]

(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]

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]

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.

[Steve Goldstein]

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]

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