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Enlarger Lens for 6x7

Ed Hurst , Apr 24, 2001; 12:48 p.m.

Just about to buy an enlarger lens to enlarge from my 6x7 negs, and would appreciate some guidance on a particular issue. My preference (as I am obsessive about image quality and optics) is to go for the Schneider APO-Componon 90mm. This is the closest to the appropriate focal length that exists in this lens range. However, I have also read that getting a longer lens (say 100 to 105mm) would be beneficial, because it would allow me to use only the area in the middle of the image circle, and hence get the most of the "sweet spot". For exmaple one posting on the web states that "lens performace suffers that far off axis as the MTF curves fall precipitously" even though they the lens would cover the image area. Now, there is no APO-Componon in this range, but there is a Componon- S.

I know that it is probably not necessary to get the APO, but I'd like to, as I am willing to spend more to get even small improvements in optical performance.

My question is: will I get better optical performance using the APO 90mm lens, or using a slightly longer non-APO lens, hence using the middle of the image circle.

Also, I've just been informed that Rodenstock do a 105mm APO. Would this be my best bet - letting me get the best of both worlds?

Many thanks in advance!

Responses


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Art Haykin , Apr 24, 2001; 05:25 p.m.

You MAY be guilty of a bit of hair splittinghere, as all lenses mentioned are excellent.There is no one perfect lens for all applications, and the longer one mentionedwill, of course, limit your ability to goto larger blow-ups easily. My guess, and it'sonly a guess, is that at f8 or 11, you shouldhave corner to corner sharpness of focus withgood image quality, provided all else is correct.Another good brand for enlarging glass is Nikor.If you are dealing with a local retailer, heshould allow you to take the lens home and test. The best test IS a test.Let us know what you decide, and why.

Greg Kriss , Apr 24, 2001; 05:51 p.m.

Have the same obsession about image sharpness and quality. From my experience only, I seem to get better results by using a 150mm El-Nikkor (older style with all metal/brass lens mount) for my 6x7 format B&W and color enlargements rather than a shorter 105mm "Apo" enlarging lens. Overall illumination is also more even (simple cosine law applies here). Other factors people overlook are bolting the enlarger column to the wall, and isolating vibration makers like voltage stablizers. Glass negative holders really vary in quality (again from personal experience only: Saunders best, Omega poor, and Bessler about equal to Saunders). Once was able to compare some enlarging lenses and found the Nikkor superior to Schneider and Schneider again superior to "Omega" labeled optics. Lately have tried some Apo Rodenstock optics and they just might be better than my beloved El Nikkors..... Oh yes, enlarger alignment is also a real factor: My 67 Saunders had to be realigned at the base of the column but my Durst 45 has always stayed aligned even after many darkroom moves and a year of storage. Good luck, Greg

Patrick Drennon , Apr 24, 2001; 06:13 p.m.

What kind of enlarger? If it is a DV-XL type of column length then you wouldn't be unhappy with any of them. If it's a C-760 you'll likely be annoyed at the limits you'll run into @ top of column. I use an 80mm APO Rodagon and have never been disappointed in edge sharpness even with 6X8 images. I've enlarged Tmax100 images to 11X14 with the APO and created the identical image with a Nikor 135mm f/5.6 and can't find any difference in intricate detail using a 5X loupe. My old Minolta 80mm f/5.6 showed fall-off in sharpness on the edges but still covered the 6X7 images (vignetted with 6X8), the APO has no DISCERNABLE degeneration in edge sharpness. I can't defend MTF ratings on enlarging lenses but I've never paid attention to them as concerns high end lenses (doesn't mean you shouldn't). I've personally been immensely impressed with every characteristic of this lens, particularly color transmission, there's an elegance to it that is hard to describe.

lloyd phillips , Apr 24, 2001; 06:17 p.m.

I have used Nikors, Schneiders, and Rodenstock (including the APO 50mm) and have found little if any discerable differences. However, in an extensive test by CTien he found 1/3 of all lens tested to be off centered. Therefore, it is perhaps critical to have return priviledges on any purchase. I currently use El Nikors although I have an additional set of Schneiders. There is also the 135mm which might give you the improvement you are seeking. NOW, for the other critical parts. I have used Besseler 4x5's, several Omegas 4x5 and used but not owned the Durst 4x5. Of these the Durst was clearly superior. There are flaws in the others although I use them for the present. The negative carriers are very important - frequent checking of alignment, and base stabilization. I would be cautious of wall mounting since some walls vibrate more than the floor (as in ,my case. I also use a vacuum easel with a non-slip base which helps keep things where they are supposed to be. This has gone further than your posed question but in my experience they are all important.

Bob Atkins , Apr 24, 2001; 06:19 p.m.

Rodenstock publish MTF plots of their enlarger lenses. If you want to be totally compulsive about this you should probably contact Schneider and Rodenstock and ask them for MTF plots.

Rodenstock recommend the APO-Rodagon N 105/4 for 6x9. Looking at the MTF plots at 6x and f8 it does look like a sharper lens than the APO-Rodagon N 80/4 in the corners of a 6x7 frame, but it may be fractionally down in the center. The 105 also looks slightly less astigmatic, but you really have to look at the plots yourself to decide what's most important to you. My guess is they'd both be perfectly fine and difficult to tell apart in actual use.

Bruce McElhaney , Apr 24, 2001; 06:42 p.m.

I can't imagine why you would need anything longer than a 90mm lens for 6x7 work. I also hope you're making smaller prints, and with an XL enlarger, because a 105mm lens on a 6x7 format will quickly meet enlargement limitations for larger prints, especially when cropped. I mostly use a newer 80mm Componon-S for both my 6x6 and 6x7 negs. I also have new Rodenstock 60mm wide angle, and a Nikor 80mm, 105mm, and 135mm. I use a standard height, Saunders 4500 VCCE enlarger and can make a sharp, cropped 20x24 print on the baseboard with my Rodenstock 60mm WA. With the 105mm I could maybe make an 11x14 print.

I've never used an APO enlarging lens, but I don't feel the need to buy one either, as I mostly do portraits, in B&W. APOs are said to focus colors together somewhat better than standard lenses. My 80mm Componon-S is very sharp and crisp. However, unlike others here, the only Nikor I like is a 50mm which I rarely use anymore. I feel the German lenses are sharper. I know for a fact that my Hasselblad lenses are sharper than my Mamiya RZ lenses.

Bruce McElhaney , Apr 24, 2001; 06:46 p.m.

Forgot to ad, it all depends on what kind of work you're doing. Sharpness at the edges is a moot point with me, as I burn in the corners/edges of most all my prints.

Duane Kucheran , Apr 24, 2001; 08:33 p.m.

One thing to consider is overall sharpness (ie. resolution) and corner falloff. A longer lens may not have as good resolution in the center as a shorter one, but the _change_ in resolution from center to edge can be significant and with some images very noticable.

I have a print of a desert scene with the sand grains visible printed with an ancient, uncoated 135 mm Federal Octar. It is not as crisp as an 80 mm Componon-S is in the center, but it doesn't seem to get proportionately softer in the corners as the shorter lens does. It also doesn't have the light falloff of the shorter lens either. To me, the print is more uniform and satisfying with the longer lens.

A 105 or at least a 90 would be my choice next time.

Chris Waller , Apr 25, 2001; 07:31 a.m.

Ed,

I use a Minolta 105mm for enlarging from 6x7 negs. I work on the assumption that the illumination is more even and it should be easier to achieve flat-field. For 35mm i use a Schneider 50mm/2.8 Componon S. This is bitingly sharp, but some of my colleagues swear by Nikon ELs. Have you seen the specs of the new Meopta lenses. I have heard a rumour that Meopta are now making lenses for certain top-marque names.

All other things being equal an APO should be better but would the difference be noticeable?

Chris.


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