80mm vs 50mm for big 35mm prints

[Tom Stanworth]

I am wondering if anyone has made the same observations as I have with enlarger lenses for big prints. :

For years I had been using longer focal lengths for enlarging 35mm because of my large 10x8 enlarger needing recessed boards for anything less than 105mm... and I have discovered after starting to use the 50mm lenses I have that (aside from the beaten old second hand Durst Neonon performing noticeably better than the nice new componon-s) that corners were sharper in the corners when using my 105mm lens with the bed on the floor and the head at the ceiling! I deliberately bought a recessed panel to allow for more comfortable big prints using the shorter 50mm lenses, but find the images disappointing in the corners compared to the much longer lenses! The images are sharp up to about 10X but then fall apart noticeably above this. They are sharp in the central edges if you follow, bu soft int eh extreme corners so it is not an alignment issue, which has been checked for). I guess there are two explanations:

1. the lenses are at the upper end of their enlargement factor at 14X and falling apart image wise (hmmm, reductions in performance, sure, but I am seeing big drops off above 10x). 16x12s look good, 20x16s not so hot.

2. The paper I am using does not manage well with the angle of projection (for a large factor from a short lens I presume the light is hitting the the corners at a steep angle).

I might now start trying the shallow recessed board and use the 80mm rather than the 105 I had been using and see what happens. Seems crazy to have to do this but if that is what it takes....

 

[archphoto]

One thing that could explain your observations: with a 105mm lens you use the center part of the lens only, with 50mm you use the whole lens including the area off-center.

Peter

 

[BobNewYork]

One thing that could explain your observations: with a 105mm lens you use the center part of the lens only, with 50mm you use the whole lens including the area off-center.

Peter

I've always used longer lenses for enlarging. I got the idea from Fred Picker and that was his exact reasoning, that the central portion of a lens was significantly sharper than the periphery. I always use 80mm, 100mm and 150mm enlarging lenses for 35, 6x6 and 4x5 respectively.

Bob H

 

[BetterSense]

This is not surprising. You are lucky that you have room to use the longer lenses. I am currently trying to effect a darkroom remodel that will allow me to use a 75mm lens on 35mm, but right now, I cannot print an 8x10 with one. But 16x20 is a big enlargement for 35mm in any case.

 

[ic-racer]

The images are sharp up to about 10X but then fall apart noticeably above this. They are sharp in the central edges if you follow, bu soft int eh extreme corners so it is not an alignment issue, which has been checked for). I guess there are two explanations:

1. the lenses are at the upper end of their enlargement factor at 14X and falling apart image wise (hmmm, reductions in performance, sure, but I am seeing big drops off above 10x). 16x12s look good, 20x16s not so hot.

Yes, I agree with you 100%. I have also made those same observations. My 'standard' 50mm is the 2.8 Nikkor and it is rated at only 10-8x. It s easy to overlook the fact that a 'standard' 50mm lens will not have good flatness of field at higher magnifications. Thus it will seem like the corners are blurry if you focus on the center. My experience is that the field curves opposite the curve of a 35mm negative, thus making things even worse if not using a glass carrier.

What I wound up doing was to get the Schneider APO 45mm HM lens. It has better (though not perfect) flatness of field at the higher magnifications. Using just the center of a longer focal length lens (as you are doing) is certainly a good way to do it. Maybe even better because you don't need the expensive HM lens, though you do need a very long column . (In fact, my 8x10 enlarger was less than my Schneider 45mm HM !)

Seems crazy to have to do this but if that is what it takes....

Not crazy at all.

 

[RJS]

Ctein in his book tested enlarging lenses and listed a few he felt were good enough for multiple formats. Schneider's 80 was one he lists as good for both 35 and 2 1/4. I have used it for quite a while for 35 and found it quite equal to my 50mm Rodenstock.

The best part is I no longer bang my head when I bend over to focus!

 

[Tom Stanworth]

Some more experimenting showed that I could get slightly sharper corners with the 50mm Neonon, but the corners suffered compared to the 80mm Rodagon. Stopping down from 5.6 to f8 improved things noticeably with sharper corners and I suspect that when I use faster papers (such as fineprint) and stop own to f11 the performance will be better still in the corners without enough degradation in the centre to matter. However, that 80mm lens is darned good....

 

[srs5694]

Any lens has a "sweet spot" for its aperture with respect to sharpness. With most lenses, this is about midway on the aperture dial, which is usually around f/5.6 or f/8 for 50mm lenses. The effect is usually more noticeable in the periphery than in the center. Mediocre lenses tend to lose more sharpness the further you get from this ideal than do better lenses. IMHO, if you're regularly printing wide open you should try printing stopped down a bit.

 

[Ken N]

I must be doing something wrong. I stop down a couple stops usually, but I always use a grain-magnifier for focusing. I'm getting sharp grain edge-to-edge. And my enlarger lenses aren't top-flight either. What am I doing wrong? I don't understand.

 

[Tom Stanworth]

Ken, I guess you are speaking in jest. What size are you printing from 35mm?

I get sharp grain from corner to corner from 35mm at at up to about 14 inches without any trouble at all and with all my lenses - even without a particularly well aligned enlarger - but things get very different when you start printing bigger than that and they deteriorate very quickly, especially at the wide apertures. If you are getting images that are truly pin sharp far corner to corner down (central edge to edge is far easier) from 35mm negs at 18 inches or so then great. Part of the trouble I have is that although I want to close the lens down three or four stops for sharper corners, I cant bec the times get waaaay to long. I am therefore trying to find a way of getting things as good as possible at, say, 5.6 - two stops down.

Some enlargers are notoriously hard to align, some are plain bent and all lenses are not equal. The Durst Neonon may well be made by Pentax, be old and have a chip in the rear element but it is the sharpest lens I have at the moment.... The corners are a lot better than the componon s at large enlargements

At wider apertures I think the image circle is noticeably smaller (or curvature is the issue) at large enlargement and at F8 I get better corners than at f5.6, I assume because the issue, whatever it is, is being corrected.

 

[BetterSense]

How long is too long for your exposure time? Are you making a lot of prints, or are you worried about reciprocity failure, or are you just impatient like me?

 

[RJS]

Evaluating enlarger lens quality through a focusing magnifier will not tell you much. Ctein, a highly respected writer/technician/photographer does his testing with a microscope, glass carriers, and I forget what all else. As all lenses are not created equal, some excellent 80 or 90mm lenses are also excellent for 35mm, and others not. Just as some 135 or 150mm lenses are great for 4X5 and also 6X9 and others not. Since my microscope is older than I am (and that is really old) I trust Ctein. Check out his book, it has some really good, useful information! And my information suggests using an extra long lens so only the center projects on paper or film just ain't true anymore, what with computer designed lenses etc. etc.

 

[Mark Fisher]

I seem to remember that wider lenses are more sensitive to film flatness in cameras and I suspect that it true for enlargers also. My enlargements in 35mm are with a 40mm lens (Leitz) and a glass carrier. My images are noticeably sharper than when I used my D2 with my Schneider lens. I swapped out the lenses to try to understand whether it was the neg holder or the lens. In my set up, getting the neg flat was much more important. Something to consider.

 

[R W Penn]

For big prints you need a Rodenstock Rodagon G 50 MM F2.8.It is made for 16x20and up. I have an extra.

 

[RalphLambrecht]

One thing that could explain your observations: with a 105mm lens you use the center part of the lens only, with 50mm you use the whole lens including the area off-center.

Peter

What happens when I stop the lens down? Do I also limit myself to the center of the lens then?

 

[ic-racer]

Evaluating enlarger lens quality through a focusing magnifier will not tell you much.

I'll have to disagree with that. The issue with using a grain focuser will be too sensitive for evaluating resolution of the grain. You will be able to tolerate more diffraction in a final print than what is evident with the grain magnifier. So it can be difficult to determine the amount of diffraction that is acceptable in the final print, based on what is seen with the grain magnifier.

 

[srs5694]

Evaluating enlarger lens quality through a focusing magnifier will not tell you much.

I'll have to disagree with that. The issue with using a grain focuser will be too sensitive for evaluating resolution of the grain. You will be able to tolerate more diffraction in a final print than what is evident with the grain magnifier. So it can be difficult to determine the amount of diffraction that is acceptable in the final print, based on what is seen with the grain magnifier.

I'd have to side with RJS on this one, based on personal experience. I did a series of tests of my five 50mm lenses a couple of years ago, and although there was a rough correlation between my impressions under the grain focuser and what I saw in enlargements, there were differences both ways. That is, some lenses produced images that looked (subjectively) crisper under the grain focuser than they did in final prints, whereas others produced somewhat blurry-looking grain-focuser images that seemed crisper in print form.

That said, there are a lot of possible reasons for this, and I didn't pursue my tests to track down the causes. It could be my judgment of grain focuser images was off because of the time required to change lenses and refocus with the new lens, for instance. (I could compare prints much more quickly.) Or it could be a weird human perception effect from the negative image with active lighting under the enlarger. Or maybe my grain focuser needed adjustment. Still, whatever the cause, I don't believe the grain focuser image can be trusted as the best metric of lens sharpness. In the end, it's the print that counts, and whatever the cause of the discrepancies I observed, the fact that there were discrepancies makes me suspicious of comparisons made under a grain focuser.

 

[RalphLambrecht]

I think, I agree will both of you when saying that a grain focuser is not a good tool to evaluate enlarging lenses. It just does what is meant to do. It allows for pretty accurate focus, but does not evaluate resolution very well, and can't do sharpness at all (need an MTF for that).

It's best to make a print, which doesn't test the lens in isolation but the whole setup, but that's what makes the print anyway.

 

[RJS]

Yes

 

[RalphLambrecht]

I seem to remember that wider lenses are more sensitive to film flatness in cameras and I suspect that it true for enlargers also. My enlargements in 35mm are with a 40mm lens (Leitz) and a glass carrier. My images are noticeably sharper than when I used my D2 with my Schneider lens. I swapped out the lenses to try to understand whether it was the neg holder or the lens. In my set up, getting the neg flat was much more important. Something to consider.

Same experience here! I'll never print without glass again.

Glass-free printing is for artists, glass-carriers are for craftsmen!

 

[BetterSense]

at what apertures are you noticeing a difference in negative flatness? I usually print at f/16 or f/11, and I wonder if it makes a difference at such small apertures.

 

[RalphLambrecht]

at what apertures are you noticeing a difference in negative flatness? I usually print at f/16 or f/11, and I wonder if it makes a difference at such small apertures.

The point is that the depth of focus is very minimal. I usually print around f/5.6-8 and at 4-10x magnification, which means 0.5-0.7 mm depth of focus if my memory serves me right (of course it depends on what CoC one is willing to accept. My medium or large-format negatives don't stay that flat without glass. The disadvantages of glass are minimal compared to its advantages in my opinion.

 

[RJS]

I 'misquoted' Ctein in regards to his enlarger lens testing. No microscope. I have just been re-reading his excellent book and find once again that there is no way in the world I am equipped, either in time, skill or knowledge to replicate his testing methodology which he describes in considerable detail. I think most of us are stuck with somewhat primitive ways of evaluating lenses and end up relying on the reputation of the manufacturers. And making the best prints we can with comparable lenses when possible. I have purchased reputedly the best quality enlarging lenses and made prints with comparable lenses from other makers and, fortunately, have not encountered any that are significantly of poor quality. But to determine resolution, contrast, lateral and longitudinal color aberrations in a meaningful way is well beyond anyplace I am going. And very much less is mostly hot air.

 

[RJS]

An addendum: stopping down more than one and at most two stops will inevitably be less sharp due to diffraction. With a well aligned enlarger and a flat negative depth of focus should not be a problem.

 

[markbau]

An addendum: stopping down more than one and at most two stops will inevitably be less sharp due to diffraction. With a well aligned enlarger and a flat negative depth of focus should not be a problem.

Stopping down from wide open or from the lenses optimal aperture? In my experience printing at wide open is to be avoided at all costs.

Mark