the last word

I re-ran the tests of the previous post with the WATE set to 21 mm focal length. The Expodisc images: f/4     f/11 f/16 The corners are fine. The garden scene: The upper right corners:   More than a bit soft, but not as soft as at 16 mm. OK The best all around f-stop… [Read More]

A reader wrote in to say that his WATE (aka Leica 16-18-21mm f/4 Tri-Elmar ASPH) had blue corners when used on the Sony a7. I thought I’d try the lens on the a7S. Expodisc shots at 16 mm: No corner casts to speak of. My usual scene at 16mm: The upper right corner: Soft, like… [Read More]

I ran a similar series of bookcase pictures as the ones I posted earlier today, only with 3 stops higher ISO settings. I put a Zeiss 35 mm f/2 Biogon ZM on the Sony a7S, using a Novoflex adapter. I put the camera on a big RRS carbon fiber tripod. I set the ISO to… [Read More]

When I post flat-as-Kansas corrected SNR vs ISO curves like I did yesterday, I often get emails saying, “That can’t be right. Show me some pictures.” I always oblige. I put a Zeiss 35m mf/2 Biogon ZM on the Sony a7S, using a Novoflex adapter. I put the camera on a big RRS carbon fiber… [Read More]

Measuring read noise is fine, but by the time you can see the read noise, the photon noise is usually pretty bad. In fact, for me, the photon noise is more important as a measure of practical image quality. Here’s a test that shows the combined effects of photon and read noise as a function of… [Read More]