Nicholas F. Jones
16-Mar-2001, 10:27
"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 len ses the axis of the lens must remain fairly central, otherwise the corners of th e 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 doe s (or does not) compromise image quality, esp. with reference to the Nikkor M se ries.
Several postings in this forum concern the performance of the Nikkor 300mm/f9 an d its alleged "falloff." But falloff is not evident in the Perez-Thalmann tests on 4x5 format (<http://www.hevanet.com/cperez/testing.html>). Not only were th e 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 f or 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 corn ers--no falloff perceptible. The diagonal of 312.5mm accounts for 96% of the ad vertized image circle at f22. So any falloff that exists with this lens will li e 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.
My question is why (or if) this is true and to what extent the Tessar design doe s (or does not) compromise image quality, esp. with reference to the Nikkor M se ries.
Several postings in this forum concern the performance of the Nikkor 300mm/f9 an d its alleged "falloff." But falloff is not evident in the Perez-Thalmann tests on 4x5 format (<http://www.hevanet.com/cperez/testing.html>). Not only were th e 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 f or 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 corn ers--no falloff perceptible. The diagonal of 312.5mm accounts for 96% of the ad vertized image circle at f22. So any falloff that exists with this lens will li e 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.