T stop Differences on 16mm and 35mm lenses

[Oliver Gläser]

I am planning on getting a mint set of Scheider Xenon 35mm format lenses for my Ultra16mm Eclair NPR when I thought of something... I was wondering if anyone knew what (if any noticable) difference in exposure one would have to compensate for on a 35mm lens mounted for 16mm shooting. My thought being that the sweetest spot of the lens is always closest to the middle and also the brightest. In fact on some lenses that I have seen there is a noticable darkening around the corners and sides. Would the stops be calculated by averaging the from the whole frame or at one point (the center) of the frame? I wonder what the difference will be, and how big. I hope this all makes sense. Thanks

[Mitch Gross]

I don't think there is anything sizeable for you to worry about. T-stop exposure is generally measured from the center and fall off usually only fairly near the corners, so the difference will be negligible at best. But if you wish to test the lenses it's as simple as paying a visit to a good camera rental house. Put the lenses up on an MTF machine and a lens projector and you'll see exactly how it is performing with the various frames and corner to corner. I highly doubt you'll need any compensation whatsoever.

[Oliver Gläser]

thanks Mitch, thats kind of what I was figuring but I thought I'd get a second opinion. I appreciate your input, its put my mind at ease again. :D

Oliver