enlarger lenses: the best.

Discussion in 'Enlarging' started by Woolliscroft, Nov 11, 2006.

  1. srs5694

    srs5694 Member

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    FWIW, I did a printing session today and performed some more extensive tests on some of my 50mm lenses than I've done before, focusing on performance at a variety of apertures. I tested each lens at four apertures (wide open [f/3.5 or f/2.8], f/5.6, f/8, and minimum aperture [f/11 or f/16]) in both the center and the periphery. I tested a 6-element Nikon EL-Nikkor f/2.8, a 5-element Vega-11U f/2.8, a 4-element Durst Neotaron f/2.8, and a 4-element Industar-96U f/3.5. I used a negative I shot for this purpose last year; it's got text samples at various sizes in both the center and the periphery, shot on Ilford Pan F+ film, which makes it easy to judge sharpness. I found that the optimum aperture for the center exposure was f/5.6 or f/8 for all of the lenses I tested (most leaned towards f/5.6, but some were virtually indistinguishable between their f/5.6 and f/8 exposures). Note that I didn't test the f/4 aperture that MichaelBriggs mentioned. In the periphery, it was another story; most got clearer up to the minimum aperture. (Of course, the true optimum could be somewhere in-between f/8 and the minimum.) The Nikon's f/8 and f/16 results were indistinguishable, though, and the difference between f/8 and f/11 was pretty small for the Vega-11U. The periphery was also where the differences were most pronounced, both in terms of differences over the aperture range and lens-to-lens differences.

    Overall, for my lenses I think using f/8 is the best compromise between center and edge sharpness if making uncropped enlargements in which edge-to-edge sharpness is important. When cropping or when subjects in the center or periphery are more important, this might change.

    I did this test with B&W film and paper; I have no idea how color might complicate things.
     
  2. RalphLambrecht

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    Michael

    Well stated and researched. Do we agree that stopped-down lenses are not the way to go?
     
  3. ZorkiKat

    ZorkiKat Member

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    The books all say, that enlarger lenses are best three stops from the biggest f/. That would be 8 or 11 in most cases.

    These books also say that in colour printing, changing exposures meant changing apertures instead of printing times. The time was to remain constant to prevent colour shifts which may arise from using different exposure times. I don't know if this still valid since I found no colour shifting when changing times in RA-4 printing.

    Jay
     
  4. Tom Stanworth

    Tom Stanworth Member

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    If you want to shoot 6x9, plug for a 105 Rodagon. They are affodable and common...and good. I have a 80 Rodagon, 105 and 150 and all are darned good from wide open (tho I normally stop down 1-2 stops unless I cannot). I printed a 20x24 print from a 5x4 neg at f5.6-f11 using the 150 and could not see any difference anywhere. I have not tested the other lenses in this regard but al produce suprt crisp prints at 1-2 stops down which should be in ther sweet spot and certainly not any worse than other apertures. Also, using an f4 lens at f5.6 or 8 means that if you have heavy burning to do you can open up a stop or two to shorten burn in times (where you might have needed a longer main exposure for your manipulations).

    I have only had one dog; a 50 f4.5 minolta which is suposed to be a good lens (tiny silver job) but vignetted VERY badly at all apertures and simply would not cover 35mm.
     
  5. RalphLambrecht

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    Michael is correct. Ctein's books refers to most lenses being at their best stopped down by just one stop. My use of 'wide-open' was too liberal. Nevertheless, my point was that the usual '2-3 stops down' rule is not verified by tests. Most enlarging lenses are better when wider open than that. I still suggest the test with the grain focuser. It will reveal the best performance for individual lenses. And yes, the test should be done in the corners and the middle, but many grain focusers can't get into the corners. Then again, why stop down further when the center is getting fuzzy already?
     
  6. srs5694

    srs5694 Member

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    If you mean making evaluations of lens performance with a grain focuser but without making a print, I don't think that's the best way to go. It takes too long to switch lenses and refocus; by the time you're done, your memory of what you've seen isn't clear enough (no pun intended) to make a good comparison. There's also the fact that you'll know which lens is in use, which can bias your judgment if you go into the test with strong preconceived notions. I prefer making test prints; you can then shuffle them to make it harder to tell which lens produced which print and compare two prints quickly.

    As to corner vs. edge performance, as a practical matter you can't change focus or settings, so you need to look at both of these with one focus setting -- presumably center focus, since as you say, that's where grain focusers work. My recent tests of my own lenses showed different optimums for center and edge performance, with edge performance improving as the lens was stopped down to at least near its minimum, whereas center performance was optimal at least a stop or two wider. If my findings are applicable beyond my equipment, then, a compromise between center and edge sharpness will often (perhaps always) be necessary.
     
  7. Early Riser

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    The original question was regarding the best lenses available for 6x9 format. In my opinion that means you are most likely going to use a 105mm lens, although a longer lens, something in the 120mm range would offer less fall off. I own El-Nikkors, Apo-Rodagons, Rodagons, and Componons. The best lenses I have, are the APO- Rodagons. They are designed for use one stop down, they have incredible resolution and very smooth gradation.

    You could try to find one of the rare APO El-Nikkors, but unless you do color printing I don't think you'll see much advantage in them especially given their high cost.
     
  8. RalphLambrecht

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    I'm not talking about comparing lenses. I'm talking about comparing the effect of f/stop setting with one lens. Just start wide-open and stop down to see how the grain get fuzzier every time you stop down further.
     
  9. eclarke

    eclarke Member

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    I just bought an brand new Nikkor 135mm f5.6 ED from Cameta for $129.00!! They still have some and do their sales on eBay..Evan Clarke
     
  10. Bob Carnie

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    I have found that the Apo Rodagons are the best for my work, I have tested the lenses against normal Rodagons and I feel the Apo's are better.
    For medium format work I purchased a 90 Apo rodagon and really like it over the 80 Apo rodagon.
    I think if one uses a lens slightly longer than the format ie 180mm Apo for 4x5 negative . 90mm Apo for medium format the results are better.
    I try to close the lens down 2 full stops even though I use glass carriers.
    This wide open to closed down debate has been going on for a very long time here. I think any sharpness test should be done only when the enlarger is critically alligned , and the film is held extremely flat.*glass carriers*
    With any good lens, flat negative, and aligned enlarger I think that at wide open the edges will be slightly soft, two stops down all image will be sharp, and 4 or more stops closed the image will be soft due to light diffracting around the lens diaphram.
     
  11. srs5694

    srs5694 Member

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    I see three problems with drawing conclusions from such a test:

    • There can be a slight focus shift with changes in aperture. In other words, if you change apertures, you may be able to improve the focus after you make that change. In my experience, this effect is tiny (perhaps negligible) with the best lenses, but it's quite noticeable with cheaper lenses.
    • Changing apertures also changes the amount of light hitting your eye. This introduces human physiology, perception, and even psychology into the equation, and those are topics that are even more complex than the optics of enlarger lenses. I wouldn't be at all surprised if changing the brightness of something would change our perception of its sharpness. In fact, I know of at least one theoretical reason to think it would: The central portions of our visual fields are dominated by densely-packed cones, which are responsible for color vision. Rods, which produce monochromatic vision, are less densely packed in the periphery of our visual fields. As illumination drops, we see more with our rods and less with our cones. That's why it's hard to perceive color in dim lighting, but to the extent that a visual task uses rods rather than cones, there's also a loss of visual acuity. Whether this effect would be significant at the levels of illumination in a grain focuser is an empirical question to which I don't have the answer.
    • Grain focusers work poorly, if at all, in the periphery of an image. Thus, any conclusions you draw will be based on the sharpness only in the center of the image. If edge-to-edge sharpness is important, you could easily sacrifice a lot of edge sharpness to achieve a tiny improvement in center sharpness.

    In conclusion, when making any comparison of enlarger lens sharpness, I prefer to use actual prints. Using a grain focuser may be a useful "quick-and-dirty" tool to spot gross differences, but as we're really interested in print sharpness, it's best to judge it directly and eliminate all the extra variables and uncertainties.
     
  12. Chan Tran

    Chan Tran Member
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    I often make my 8x10 from 35mm at f/5.6 only because it gives convienient time. May be now I should use f/4? My lens is the Nikkor f/2.8 lens.
     
  13. Tom Hoskinson

    Tom Hoskinson Member

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    Test your lens to determine the optimal aperture. As a test negative, I have always used (since the 1960's) a USAF Resolution chart (chrome on glass - available from Edmund Scientific).

    As SRS594 says, be sure to check the image resolution at the edges of the enlarged image - (this also helps check your enlarger alignment) and be sure to check for focus shift as you change apertures on your enlarging lens.
     
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  15. Jim Jones

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    Fine grain is sharply resolved edge to edge with my old f/2.8 at either aperture. It still looks good enough at f/8, which covers film coverature, enlarger misalignment, and focusing errors better. There is vignetting at f/2.8, though.
     
  16. Tom Hoskinson

    Tom Hoskinson Member

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    My old 50mm f2.8 El Nikkor doesn't really get sharp until it is stopped down about half way between f 5.6 and f8.0. This particular lens also exhibits significant focus shift from f2.8 to f8.0.

    I also have a new N series 50mm f2.8 El Nikkor that is very sharp across the entire field at f2.8 and exhibits no focus shift as it is stopped down. I bought this lens because of its UV transmission characteristics. I bought several other N series El Nikkors (in various focal lengths) for the same reason.
     
  17. RalphLambrecht

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    Just do the test, you'll see what I'm talking about. It's rather obvious. One can clearly see what the best aperture is. When I made the test prints, it verified the grain-focus test but wasn't as obvious.

    It' not too easy to do a series of test prints at different f/stops, by the way. You need to have the same exposure for all prints and several factors have to be considered to do that (reciprocity, f/stop accuarcy). If you don't have the same exposure, you can't really compare the prints. Darker prints often look sharper than lighter ones.
     
  18. Tom Hoskinson

    Tom Hoskinson Member

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    My chrome on glass AF resolution images have no grain.
     
  19. Weldon

    Weldon Member

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    That's heavy Zork...
     
  20. Tom Hoskinson

    Tom Hoskinson Member

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    Zork from Ork??

    Dunno about Zork, but grainless is what you get when Edmunds deposits the chrome onto the glass plate.

    I have contact printed these AF resolution charts onto Kodak Tech Pan & these Tech Pan copies are also grainless.

    A grain magnifier is only useful in a limited sense as an image magnifier with these high resolution test negs- and they are what I have used for years to test enlarger lenses. I usually make prints on high resolution glossy white enlarging paper and evaluate them with a loupe or microscope.
     
  21. richard ide

    richard ide Member

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    Also the best analogue device for analoizing the aerial image of a lens with a microscope.

    Tom, can I borrow yours for a couple of days? ;-)
    My method is a little more primitive and I must allow for error factor.
     
  22. OP
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    Woolliscroft

    Woolliscroft Member

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    I just want to say many thanks to everyone for the great response to my original question. You have given me a lot to think about. Right now I am using a Durst Neonon f: 2.8, 50mm for my 35mm printing. For medium format I have two lenses from a (I think) much under rated British maker, Taylor Hobs and have their Ental 80mm, f: 4.5 for 6 x 6 and an Ental 108mm f: 4.5 for 6 x 7, which would probably also cover 6 x 9. These out perform my University's Componar lenses, but I have never been able to play with the Componons. Whatever: I think I can still do better, so I will see if I can get a go with some of the Componons, El-Nikors and Rodagons that people have recommended.

    Many thanks again.

    David.
     
  23. srs5694

    srs5694 Member

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    I've got a Durst Neotaron lens that's a 4-element design made by Rodenstock. I'm not positive, but I believe the Durst Neonon is a 6-element design. I don't know offhand if it's made by Rodenstock, though. I don't know a thing about your Taylor Hobs lenses, though.
     
  24. Tom Stanworth

    Tom Stanworth Member

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    I heard Neonons are the same as Rodagons on various forums but could not be sure.
     
  25. Tom Stanworth

    Tom Stanworth Member

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    Making test prints at different apertures at the same exposure is not that hard! To account for f stop inaccuracies, lamp temperatures etc once you have applied the inverse rule, you just tweak until the exposure looks the same. If the prints looks the same density wise any invisible differences are not really going to have a practical bearing on 'aparrent best f-stop'.

    Assuming you can match test prints for density, which should take little time, if they dont look that different at different F stops to the naked eye, why should we be worried about it? It does not matter what things look like under a magnifier if the prints are indistinguishable.
     
  26. RJS

    RJS Member

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    The difficulty I am having with testing enlarging lenses goes this way: I have a 50mm Apo Rodagon, an 80mm Schneider Componon S, an 80mm Nikkor N, a 105mm Nikkor N, and two 135mm Rodagons, one about 30 years old the other about 12. Given that I make all the tests Ctein describes and find some or all of my lenses less than stellar. If I buy used on EBay at decent prices (currently a new non-refundable 135mm Nikkor for $130) or used - returning perfectly excellent looking lenses because of whatever testing I do seems difficult. Buying new from B&H is still quite expensive. It is tempting to accumulate even more lenses and try them all and use only the best, but then I print mostly 8X10, some 11X14 and rarely 16X20. Will any differneces I may find be worth the many hours of testing? The lenses I have produce very sharp looking prints. Are better/sharper to be had? Where does this stop?
     
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