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View Full Version : 240mm lens with little to no vignetting or center filter? (8X10)



Mexipike
2-Apr-2018, 22:31
A photographer I’m working with is working to capture beach images using an 8x10 camera and is currently using ektar 100.

He really wants to have zero edge darkening and would rather not deal with that in digital post as he plans to print huge and feels the slightest error will be evident.

He is currently using the 240mm Fujinon F9.

If he switched lenses would he be able to get a large enough image circle so as to have no edge darkening? He was thinking about the Rodenstock sironar.

Or is he not able to get that result unless he uses a center filter?

His concern with a center filter is that he likes the 100 ektar and doesn’t want the ocean to be too blurry, but would probably have to go up to 400 Portra if he went with the center filter, however, he’s willing to do that if it is what’s necessary for even edges.

Dan Fromm
3-Apr-2018, 05:02
Cos(theta)^4 is more-or-less the law with nearly all LF lenses. For it, all that matters is focal length.

Ain't no center filters made for lenses that cover < 90 degrees.

Pere Casals
3-Apr-2018, 06:18
He really wants to have zero edge darkening and would rather not deal with that in digital post as he plans to print huge and feels the slightest error will be evident.

This is weird, photoshop corrects falloff perfectly, with no quality loss, just edit with 16bits per channel. And just overexpose a bit if corners have important detail and are in dark scene areas.

The 240mm in 8x10 has a relatively mild falloff if stopping a bit. The corner is at 33 with 240/8x10, so cos^4 is 0.5, so you have 1 stop falloff in the far corners, so perhaps I'd overexpose by some 1/2 stop to be confident that far corners are not underexposed. Negative color film has excellent highlight latitude, but in the Ektar case better if not abused in that way.

Just a suggestion, take a Nikon F65 with a 24mm (or 28mm, what you have) and a roll of ektar, shot a test roll (with some bracketings) and see what happens with photoshop correction, a 24mm should have similar falloff, if that works ok then forget about other lenses and center filters.

As Dan says, all 240mm lenses should have similar fall off in the corner, some may have slightly less because tilted pupil design, but that's irrelevant.

The Sironar is also excellent, but single reasons I find to get it it's because the larger image circle, allowing more translational movements, or if wanting f/5.6 aperture for portraits.