80mm vs 50mm for big 35mm prints

[RJS]

Quoting from the same source: stopping down one stop is almost always necessary; wide open he found only one lens that performed well. But stopping down more than two stops gave lesser quality; diffraction begins to degrade performance. If you consult his test results I believe you will find that with all the lenses he found acceptable the optimum performance, considering both resolution and contrast was obtained stopped down between one and two stops. This is the only source of which I am aware of systematic, scientific testing of enlarging lenses. ObviouslyI highly recommend Ctien's book as as the best and apparently only source of information about enlarging lenses.

 

[RalphLambrecht]

Quoting from the same source: stopping down one stop is almost always necessary; wide open he found only one lens that performed well. But stopping down more than two stops gave lesser quality; diffraction begins to degrade performance. If you consult his test results I believe you will find that with all the lenses he found acceptable the optimum performance, considering both resolution and contrast was obtained stopped down between one and two stops. This is the only source of which I am aware of systematic, scientific testing of enlarging lenses. ObviouslyI highly recommend Ctien's book as as the best and apparently only source of information about enlarging lenses.

I second all of that. Actually, it was this book after which I changed to printing with glass carriers exclusively and limited the aperture to f/5.6-11. This is the best aperture range for my lenses, but the limited depth of focus necessitates that I use a glass carrier for my typical enlargement factors.

 

[markbau]

What is the name of the book you refer to? I have his post exposure book and his digital retouching book but can't find any other books of his on his website or on Amazon. I do recall an article he wrote on enlarging lens tests in D&CCT many years ago.

 

[RalphLambrecht]

What is the name of the book you refer to? I have his post exposure book and his digital retouching book but can't find any other books of his on his website or on Amazon. I do recall an article he wrote on enlarging lens tests in D&CCT many years ago.

I was referring to his book 'Post Exposure'.

 

[markbau]

I've just spent an enjoyable hour or so after pulling that book off the shelf, dusting it off and re-reading some chapters, it is quite a few years since I opened it. A sheath of notes were inside where I'd started a letter to Ctein (that I never sent) its a great book but there were a few things that I questioned, (I was going to write to him and ask for some clarification) He wrote that a 80mm componon s lens does not cover a 67 neg. I was using that lens for 67 printing and was very interested in his remarks. A little while later I did a print workshop and asked the teacher about how to test for light fall of, we did a test and the lens showed no signs of light fall of! I also thought his chapter about split filter printing contained some contradictory statements but that is a matter for another thread.

 

[RalphLambrecht]

I've just spent an enjoyable hour or so after pulling that book off the shelf, dusting it off and re-reading some chapters, it is quite a few years since I opened it. A sheath of notes were inside where I'd started a letter to Ctein (that I never sent) its a great book but there were a few things that I questioned, (I was going to write to him and ask for some clarification) He wrote that a 80mm componon s lens does not cover a 67 neg. I was using that lens for 67 printing and was very interested in his remarks. A little while later I did a print workshop and asked the teacher about how to test for light fall of, we did a test and the lens showed no signs of light fall of! I also thought his chapter about split filter printing contained some contradictory statements but that is a matter for another thread.

What was your teacher's approach to check for light fall-off?

 

[RJS]

Ralph, I notice in his book Ctein says he does most of his printing with glassless carriers. I have found that putting together a glass carrier for 35mm is a daunting task. I have to tape the negative in place on one piece of glass and then place a second piece on top. Then, taping a mask on top of the whole business turns printing one negative into a days work. Since I print no larger than 11X14 my prints seem acceptably sharp using a glassless carrier with my 80mm Schneider Componon at f8. But 35mm I think is the least demanding for negative flatness. I have a Beseler "negaflat" carrier for 4X5 which I believe gives flatness equal to glass. I admire your tenacity and craftsmanship - and you write a good book too! And Markbau; Ctein gives very clear directions for testing for falloff. Or, you may have an exceptional sample of the Componon S.

 

[RalphLambrecht]

Ralph, I notice in his book Ctein says he does most of his printing with glassless carriers. I have found that putting together a glass carrier for 35mm is a daunting task. I have to tape the negative in place on one piece of glass and then place a second piece on top. Then, taping a mask on top of the whole business turns printing one negative into a days work. Since I print no larger than 11X14 my prints seem acceptably sharp using a glassless carrier with my 80mm Schneider Componon at f8. But 35mm I think is the least demanding for negative flatness. I have a Beseler "negaflat" carrier for 4X5 which I believe gives flatness equal to glass. I admire your tenacity and craftsmanship - and you write a good book too! And Markbau; Ctein gives very clear directions for testing for falloff. Or, you may have an exceptional sample of the Componon S.

Why is it so difficult? Don't you have a negative carrier with glass for your enlarger? Also, one-sided glass is better than none. If I remember correctly, the side towards the light source should be glass, at least.

 

[markbau]

I think we just made a print (without a neg) that was mid grey and looked to see if there was any difference between the centre and the edges, I think we made an 11 x 14 print. I just read the Ctein method which involeves the additional step of comparing the centre and edges with a step tablet. I also tested my two 50mm lenses the same way and found that the Schneider was free of fall off, the Nikon had slight fall off.

 

[patrickjames]

Have you explored the possibility that your enlarger is misaligned?

 

[RalphLambrecht]

I think we just made a print (without a neg) that was mid grey and looked to see if there was any difference between the centre and the edges. ...

You need to do this full-frame, at the hardest possible paper grade!

 

[ic-racer]

If you did not find any light fall off then your testing method was not sensitive enough. A quarter stop falloff at the corners is detectable but it may not ruin you prints.
http://www.schneideroptics.com/pdfs/photo/datasheets/componon-s/componon-s_40_80_1.pdf

 

[Ronald Moravec]

A quality 50 will be sharp into the very corners and an 80 mm is not necessary.

Take care your enlarger is alligned and the magnification required is withing the design perameters of the 50 mm lens. Some are good for small mag, others are made for large magnification.

Also be sure the negative is flat which usually means at least a single side glass carrier.

The longer than normal lens may have been true 50 years ago, it is definately not true today.

 

[RalphLambrecht]

The longer than normal lens may have been true 50 years ago, it is definately not true today.

Unfortunately, I was not able to find enlarging lens MTFs to verify this statement.

 

[Tom Stanworth]

A quality 50 will be sharp into the very corners and an 80 mm is not necessary.

Take care your enlarger is alligned and the magnification required is withing the design perameters of the 50 mm lens. Some are good for small mag, others are made for large magnification.

The longer than normal lens may have been true 50 years ago, it is definately not true today.

Maybe not, but the issue may be how necessary the higher mag designs are when exceeding the ranges advertised for the more standard models. i.e does an APO rodagon print visibly better corners at 14x than the standard model.

With glass carriers and an enlarger that is aligned as far as I know (checked and producing pin sharp 18" corner to corner prints from 6x7 with a 105 Rodagon:

18" is 13-14X of 35mm depending on minor cropping. This is over and above the 10x recc for most 50mm 2.8 non APO/HM type lenses but within the 15x max posted for the 50 2.8 rodagon. I dont know how much of a deterioration is implied by being above the 10x optimum.

I am going to recheck everything when home next and be sure I have not overlooked something. I will also try a laser alignment tool, but it is odd that I can get pin sharp large prints from 6x7 with the 105 and better corners from the same aperture with this and the 80mm than either of the 50mm lenses. the 50mm lenses are good at f8 and to all intents and purposes perfect at f11, only print times are too long. I need great results at f5.6 which stresses everything much more and should result in a smaller IC for the lens.

It is perhaps telling that the prints are all pin sharp on all edges and only the corners suffer at 13-14X. One or more edges should be worse if out of alignment but they are perfect. Its only the last 3/4inch of the corners!

 

[Dietmar Wolf]

I use Durst M650 color head enlarger with nikon 50mm lens. I stop down to f8. I enlarge 35mm 9 X

I recently switched from glass to glassless printing. I recognised a noticeable gain in sharpness. Also the overall picture quality improved much.


I had at top antinewton glass and at bottom normal glass. I guess the antinewton glass made the light even more softer. That is just guessing, I dont know exactly, and to be honest I dont care about the reason. I am just very happy now.


Second, I dont have this awfull dust problem around the glass anymore.

 

[RalphLambrecht]

I use Durst M650 color head enlarger with nikon 50mm lens. I stop down to f8. I enlarge 35mm 9 X

I recently switched from glass to glassless printing. I recognised a noticeable gain in sharpness. Also the overall picture quality improved much.


I had at top antinewton glass and at bottom normal glass. I guess the antinewton glass made the light even more softer. That is just guessing, I dont know exactly, and to be honest I dont care about the reason. I am just very happy now.


Second, I dont have this awfull dust problem around the glass anymore.

This is very unusual and the opposite from can be expected. You must have changed something else, or maybe your glass was not clean enough. 'awful dust problems' sounds like a cleanliness issue. It's hard to tell from a distance, but glassless printing is not sharper, if anything, the opposite is true. The sharpest image is achieved if the negative is truly flat, and that never is the case with glassless carriers.

 

[Steve Smith]

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.

That's interesting. I have an 80mm Schneider lens which I use for 35mm, 6x4.5 and 6x6. When I got my RB67 I bought a 105mm enlarging lens but I still tend to use the Schneider 80mm for 6x7 negatives.


Steve.

 

[Tom Stanworth]

some people suffer a lack of sharpness due to using Anti newton glass underneath instead of on top or having AN glass with too pronounced a pattern. With my glass set up the overall results are miles better than glassless (in terms of uniform sharpness) and there are no popping issues either. Sharpness is stunning with super crisp grain. I find cleanliness a non issue as my neg is effectively sealed in the carrier which is sealed in the enlarger. It takes all of 30s to get the carrier clean and mount the neg.

IMO for larger prints glass carriers are essential. The larger prints require more open apertures to keep exposure times sensible and you wont find it easy using f11/16 when making a 20x16 from a properly exposed 35mm neg unless you have some insanely powerful head. At f5.6 or so, and bowing of the neg will be immediately visible in the prints and popping may well repeatedly write them off. This has been true in the four enlargers I have had. Now I just have this issue with the extreme corners with large prints off 35mm.... which I suspect is a lens field curvature issue. Edges are super sharp on all sides and the extreme corners all register the same error (ie can be corrected with about the same about of focus compensation in the same direction. Were alignment an issue, corners on the left would surely require a focus adjustmentin the opposite direction of the right etc and the fall off in sharpness would be gradual from the area focused (centre). Mine remains perfect until the last 3/4" which is rather like a lens running out of coverage.

 

[Daniel Ferri]

Tom,

it might not be the case, but please check:

you are using a 10X8 with a 50mm lens.
Your recessed lens board must be very deep, even with the focus cranked right up, and you bellows compressed.

You may find that when printing large prints, the fall-off in the corners is not due to the lens, but to the vignetting by the recessed lensboard.

To check this: 1- put a piece of white paper inside and around the recessed lensboard, and see if the lens projects the corners of you neg on it;
2- enlarge at small magnification, ei. 5X7 or 10X8, and see if your corners are better;
3- check your light source alignment, and most importantly that your condensers are matched to your neg size.

Let me know how you get on.
Rgds
Danny

 

[fotch]

This is very unusual and the opposite from can be expected. You must have changed something else, or maybe your glass was not clean enough. 'awful dust problems' sounds like a cleanliness issue. It's hard to tell from a distance, but glassless printing is not sharper, if anything, the opposite is true. The sharpest image is achieved if the negative is truly flat, and that never is the case with glassless carriers.

Interesting comment. I thought glass made the negative plane flat so edge to edge was sharper. Never had a problem getting any size negative focus very sharp although cannot say that the entire negative (edge to edge) was sharp.

 

[Tom Stanworth]

Danny,

I have been wondering about this too - some sort of mechanical vignetting effect. I have quite a bit of investigating to do thats for sure. I think at this stage I will get my 35mm work done by a custom printer and continue with my MF. Looks like I will have to sell up my darkroom before too very long as a house move (almost certainly overseas) is on the cards in the next year. hopefully when I start up again the problems will have mysteriously vanished (with a different enlarger etc). I am not looking forward to seeing most of my kit go, although I will try to hang onto things like print washers, easels, lenses etc.

 

[RJS]

You MUST align your enlarger accurately. Use one of the optical tools (Versalign, Zigalign) for this. Obtain a top quality 50mm enlarging lens - a list is available in Ctein's book (Componon S, Nikkor N, Apo Rodagon are some). Do not stop down more than 2 to 2 1/2 stops. More gives a less sharp image. You will have plenty of coverage from one of these lenses and they are all corrected for greater enlarging ratios than nearly all the longer lenses - the manufacturers are aware that 35mm gets 'blown up' more than 6X6. Spend a few dollars and get Ctein's book; people posting here sometimes offer misinformation. Ctein is an MIT graduate with many years of experience and has conducted extensive testing of enlarging lenses. You neglect this source at your own peril!

 

[wiltw]

Ctein went to Caltech, with double degree in English and in Physics

http://ctein.com/whoami.htm

 

[RalphLambrecht]

Einstein taught at Princeton and stuck out his tongue while posing once. Does that mean he was always right?