Archives for August 2015

The Sony alpha 7 Mark II (aka a7RII) has a silent shutter mode. When running silent, the mechanical shutter is on vacation: the sensor does all the work. The mechanical shutter is a rabbit, completing an exposure in 1/250 second (for shutter speeds faster than that, a slit moves across the sensor, but it takes… [Read More]

I received a request to look at what, if any, lowpass filtering the a7RII performs on dark-field images at ISO 100. Dark field images are mostly Gaussian noise at higher ISOs, although they can contain low-frequency energy do to pattern variations.  A standard technique to remove the pattern variations is to subtract two dark frames… [Read More]

The data in yesterday’s post was pretty noisy, but it seemed to indicate that somehow the silent shutter mode on the Sony alpha 7 R Mark II (a7RII) might produce images that were slightly less sharp than the electronic first curtain shutter (EFCS) mode. I foolishly speculated that the reduced bit depth of silent shutter… [Read More]

I put the Leica 280mm f/4 Apo-Telyt-R on both the a7R and a7RII, mounted the lens collar to an Arca Swiss C1 head on a set of RRS TVC-43 legs, set the whole thing on a vinyl tile over 6 inch concrete floor, and made some slanted edge photographs at various shutter speeds. With the… [Read More]