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View Full Version : ACTUAL IC of the Schneider 72XL, Nikkor 90/8, etc. 90's?



audioexcels
17-Jun-2008, 05:04
I know Schneider highly underrates the IC of their XL lineup and I actually read that the 72XL has an actual IC at F22 of 260mm's. I may need to check back on the thread where this is stated, but I'm fairly certain about this since the XL line seems to have 30 more mm's of the stated IC that Schneider gives...another example being the 110XL which is published at 288mm at F22, but can fill the 8X10 sheet.

I'm curious about the lenses of the modern period that are the most underrated per spec sheet. One of these lenses I believe is the Nikkor 90/8 which, again, if I remember correctly, read that a person used this lens often on 6X10!

How much "actual" IC does the Schneider 72XL have and does any lens in the 90mm range (excluding the 90XL) have similar or even more actual IC than the 72XL?

Thanks to those that have used both the Schneider 72XL and the 90/8 and even other 90's that have a similar actual IC as the 72XL.

mrossano
24-Jun-2008, 14:42
Reports of image circles that are much in excess of manufacturer's stated coverage are very often in the eye of the beholder. Schneider specifies image circle data based on some one or more acceptance criteria. After having examined their MTF charts and other technical data over the years, it's clear that the limiting factors are different for different lenses; sometimes MTF falloff, sometimes field curvature, sometimes illumination falloff, sometimes distortion, etc. Whatever factors that they may be considering in their specs, your results outside of that circle may still be fine for you. For example, many people find that the G-Claron lenses give good results well-beyond the 64 degree coverage that Schneider rated them at. A figure of 80 degrees is often stated for f/45. My personal experience is that the field curvature out that far is too obnoxious to deal with, even though there certainly is plenty of good image if you're willing to make the appropriate adjustments. I simply don't have the patience. Another example from Kowa would be the Computar/Apo Kyvytar lenses. These are often used out to field angles of 90 to 95 degrees. Once again, there is a lot of field curvature to deal with. For these reasons I sold some otherwise very nice lenses in the past year, after trying them and being dissatisfied with the working characteristics as wide angles. The only lens I've used so far that I've pushed well-beyond its limits and been happy with has been a 240mm Germinar W. That lens is magic! Very little field curvature out to 80 degrees (400mm image circle) and superb sharpness and contrast from 2:1 to infinity. The macro performance was so good that I sold a perfectly fine 180mm Apo Macro Sironar, feeling that, for my purposes, it was redundant.

The Nikkor SW f/8 lenses do seem to cover beyond what Nikon states. I have a 150mm that never runs out of image circle, and the 120mm that easily, rather than just barely, covers 8x10.

As the saying goes, "Your mileage may vary."

audioexcels
24-Jun-2008, 18:57
Reports of image circles that are much in excess of manufacturer's stated coverage are very often in the eye of the beholder. Schneider specifies image circle data based on some one or more acceptance criteria. After having examined their MTF charts and other technical data over the years, it's clear that the limiting factors are different for different lenses; sometimes MTF falloff, sometimes field curvature, sometimes illumination falloff, sometimes distortion, etc. Whatever factors that they may be considering in their specs, your results outside of that circle may still be fine for you. For example, many people find that the G-Claron lenses give good results well-beyond the 64 degree coverage that Schneider rated them at. A figure of 80 degrees is often stated for f/45. My personal experience is that the field curvature out that far is too obnoxious to deal with, even though there certainly is plenty of good image if you're willing to make the appropriate adjustments. I simply don't have the patience. Another example from Kowa would be the Computar/Apo Kyvytar lenses. These are often used out to field angles of 90 to 95 degrees. Once again, there is a lot of field curvature to deal with. For these reasons I sold some otherwise very nice lenses in the past year, after trying them and being dissatisfied with the working characteristics as wide angles. The only lens I've used so far that I've pushed well-beyond its limits and been happy with has been a 240mm Germinar W. That lens is magic! Very little field curvature out to 80 degrees (400mm image circle) and superb sharpness and contrast from 2:1 to infinity. The macro performance was so good that I sold a perfectly fine 180mm Apo Macro Sironar, feeling that, for my purposes, it was redundant.

The Nikkor SW f/8 lenses do seem to cover beyond what Nikon states. I have a 150mm that never runs out of image circle, and the 120mm that easily, rather than just barely, covers 8x10.

As the saying goes, "Your mileage may vary."

Thanks a lot for your input. I know the Nikkor 150 is a wonder for the IC it has, but how useful do you find it by comparison to the 120? I'd imagine it would be the primary wide lens of choice, though it does sacrifice 30mm's of focal length but gains 88mm's of IC plus the rest of the conservatively rated coverage they both produce.

Curious about the 120 and movements...during what situations will you use this lens and how much can you get out of it movemennt wise?

Thanks a lot for everything you said about field curvature and use with the various lenses. It's very informative and hopefully others will read it as I find it extremely valueable/useful.