Fast wide-angle lens distortion at wide open

jcc · Jul 29, 2014

Does anyone have a 90mm f/4.5 lens? 65mm f/4.5 or f/4? I'm not looking for one, but would just like to know how much distortion exists if any around the edges of a 4x5 frame at the fully open aperture. Phone pics of the ground glass image would suffice. Thanks!

Ian Grant · Jul 29, 2014

Modern LF wide angle lenses don't distort like many lenses for 35mm & MF SLRS because they aren't compromised designs and are essentially symmetrical.

So you don't see distortion on the GG screen at any aperture, However they aren't optimised to be used at full aperture and reach their best all round sharpness at f22.

Ian

Xmas · Jul 29, 2014

Photos of faces or other similar solid objects will show a projection distortion which is not the lens but our brains...

You cannot use a wide for group photos and expect repeat customers.

David A. Goldfarb · Jul 29, 2014

Wide open, you won't see aperture-related distortion so much as falloff of illumination at the corners, though these fast lenses have very large image circles for their focal lengths. They tend to be optimized for f:22 (particularly for use with a center filter) or with some modern ultrawide lenses shorter than 60mm, they may be optimized for f:11. You may find that the image looks kind of "stretched" at the corners with an ultrawide like 55mm or 47mm on 4x5", but that's just the quality of any rectilinear image at any aperture with such a wide lens.

jcc · Jul 29, 2014

Ian Grant said:
Modern LF wide angle lenses don't distort like many lenses for 35mm & MF SLRS because they aren't compromised designs and are essentially symmetrical.

So you don't see distortion on the GG screen at any aperture, However they aren't optimised to be used at full aperture and reach their best all round sharpness at f22.

Ian

Ok, not "distortion"... Let's call it warpiness of the out of focus areas?

jcc · Jul 29, 2014

David A. Goldfarb said:
... the image looks kind of "stretched" at the corners with an ultrawide like 55mm or 47mm on 4x5"...

Yes! That's what I'm looking for/talking about.

David A. Goldfarb · Jul 29, 2014

You might start to see the "stretched" look around 65mm on 4x5" (depending in part on the composition and what's in the near field), but it's not connected particularly with using fast lenses wide open. Any ultrawide can have that look at any aperture.

jcc · Jul 29, 2014

David A. Goldfarb said:
You might start to see the "stretched" look around 65mm on 4x5" (depending in part on the composition and what's in the near field), but it's not connected particularly with using fast lenses wide open. Any ultrawide can have that look at any aperture.

Oddly enough, I've noticed it on my 90mm f/4.5, but not the 90mm f/6.8 or 65mm f/5.6. Less stretch/warp on the 90mm f/4.5 when stopped down to shooting aperture though.

Xmas · Jul 29, 2014

Each lens will have some distortion as you go off axis even full symmetric process style, even Gary Powers U2 photo reccy wide lens.

But a pinhole 'wide' will also exhibit a rectilinear projection problem.

You can use this to good effect to make a shot or it can ruin a shot.

Wides are difficult to handle.

jcc · Jul 29, 2014

Xmas said:
Each lens will have some distortion as you go off axis even full symmetric process style, even Gary Powers U2 photo reccy wide lens.

But a pinhole 'wide' will also exhibit a rectilinear projection problem.

You can use this to good effect to make a shot or it can ruin a shot.

Wides are difficult to handle.

I just want to see what they look like. Too bad I can't get all the lenses onto one long board and do a row comparison.

Fast wide-angle lens distortion at wide open

jcc

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Fast wide-angle lens distortion at wide open

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