Tessar design LF lenses

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"Certain lenses (such as the Tessar type) can give magnificent results within a quite limited field in relation to their focal length. Obviously, with such lenses the axis of the lens must remain fairly central, otherwise the corners of the image will show poor definition and less brilliance" --Ansel Adams, Camera and Lens, p. 193.

My question is why (or if) this is true and to what extent the Tessar design does (or does not) compromise image quality, esp. with reference to the Nikkor M series.

Several postings in this forum concern the performance of the Nikkor 300mm/f9 and its alleged "falloff." But falloff is not evident in the Perez-Thalmann tests on 4x5 format (). Not only were the two lenses tested (both 1980's vintage) sharp at f11, 16, and 22, but at these apertures no falloff was observed (with the sole exception of small degradation with one of the two lenses at f16).

Nikon's advertized image circle at f22 for the lens is 325mm, making it usable for 8x10. My own 8x10's, taken at f22 and smaller apertures in horizontal format with no movements except for moderate front rise, are sharp from center to corners--no falloff perceptible. The diagonal of 312.5mm accounts for 96% of the advertized image circle at f22. So any falloff that exists with this lens will lie outside the image circle claimed by the manufacturer.

The number of elements in Tessar lenses is sometimes mentioned with reference to image quality. Is a lens with only four elements (in three groups) somehow at a disadvantage?

I would also like to solicit comments from users of other Nikkor series M lenses, esp. the 450mm/f9, which has an advertized image circle of 440mm at f22 and so is usable in 8x10 and even bigger formats.

-- Nick Jones (nfjones@pitt.edu), March 16, 2001


My own experiences with (modern) Tessars show, that these lenses are outstanding when used within their limits. I own a modern Schneider Xenar 6.1/210. This lens is intended for 5x7", so it hat lots of movement when used with 4x5. I made several landscapes with it using only small (if any) movements and found the results exceptionally sharp. Direct comparisons with a Apo-Symmar 5.6/180 showed no advantages for the Apo-Symmar even when 10x enlargements were made.

The Tessar is not very good wide open, but stopped down it can rival the best. Just don't try to wring the last drop of image circle out of it.

-- Martin Jangowski (martin@jangowski.de), March 16, 2001.


The tests Chris and I did were only on 4x5, with the lens centered (no movements). As such we are only using the center 153mm of that 325mm image circle. Call it the "sweet spot" if you will. One thing we've noticed with longer focal lengths, especially for lenses with generous coverage, is that the performance is generally pretty even across the 4x5 frame. Wide angles, tend to have more fall-off in the corners (both in terms of light loss and degredation of sharpness). The light loss is of course, why center filters are available for these lenses. The loss in sharpness makes sense too since diffraction is dependent on the angle of transmission. An ultrawide angle has lower theoretical diffraction limits in the corners of the frame than it does in the center. So, not only are ultrawide angle lenses with big coverage more complex designs to begin with, they also have the laws of physics working against them.

So, back to your 300mm Nikkor M. Neither Chris I are currently shooting with 8x10, so we haven't done any tests on that format. All of our test chart shooting has been done on 4x5. I have shot a few sheets of film 5x7 with the 300mm Nikkor M, but no formal testing. The M series Nikkors are excellent executions of the tessar design. I also have a 200mm Nikkor M that I use when backpacking with a 4x5. If I keep the movements modest, the performance is indistinguishable from my 210mm APO Symmar. Still, when weight isn't a concern, or I'm shooting 5x7, I use the APO Symmar for the added coverage. I also used to own a 450mm Nikkor M, but never shot anything larger than 4x10 with it. So, I have found the M series Nikkors to be outstanding performers within the centers of their published images circles, but I have not really pushed any of them to the limits of their published specs.

I know there are a fair number of 8x10 shooters out there using the 300mm Nikkor M for landscape photography, but I have never seen any published test results on that format. Larry Huppert has done some testing of a 300mm Nikkor M, 300mm Fujinon A and 300mm Fujinon C on 4x5, but with extreme movements to see which one had the largest coverage that he considered critically sharp. In his tests, he concluded that they all had smaller usable image circles than the published data suggests. However, he is a 4x5 architectural shooter, not an 8x10 shooter. So, if he's making 20x24 enlargements from 4x5 and you're making 8x10 contact prints, you may have different expectations and different definitions of "critically sharp". Hopefully Lary will chime in with his results. FWIW, I believe he went with the 300mm Nikkor M. He said the 300mm Fujinon A had a little more coverage, but it wasn't quite as sharp in the center of the field or as contrasty as the Nikkor M.


-- Kerry Thalmann (largeformat@thalmann.com), March 16, 2001.

Re: "The number of elements in Tessar lenses is sometimes mentioned with reference to image quality. Is a lens with only four elements (in three groups) somehow at a disadvantage?"

The more elements, the more degrees-of-freedom the designer has to play with in achieving the designers goals. The designer can vary the glasses selected, the curvature of each elements, the spacing of elements, etc. There are limits to what can be accomplished with a given number of elements, and if the goals aren't met, more elements are probably needed.

A four-element lens can deliver excellent image quality, but over a lesser angle than a more complex design. The Tessar is a classic design that can deliver excellent image quality, but over a lesser angle than some more complex designs. If the coverage is sufficient for your needs, than a Tessar is a good choice. Tessars are typically used as normal (perhaps slightly longer than normal) to moderately long lenses.

-- Michael Briggs (michaelbriggs@earthlink.net), March 16, 2001.

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