I still want to use the Sony a7R for macro work. So today, I set out to discover how long the exposures have to be before shutter shock doesn’t matter. I mounted a Zeiss 135mm f/2 Apo Sonnar ZF.2 to the camera with a Novoflex adapter. I mounted a RRS L-plate to the camera, clipped… [Read More]
Archives for March 2014
Penny wise…
I’ve been using a 49/77mm Heliopan step-up ring to mount my 77mm Heliopan variable ND filter on the Zony 55mm f/1.8 lens. The female threads in the ring had developed a burr that made threading the filter on a little tricky. Sometimes it seemed like it was on firmly, but I noticed that I could… [Read More]
Real-world a7/a7R handheld images
Enough of these charts. I’ve been asked for some real-world handheld images from the Sony a7 and a7R . Happy to oblige. I made five images with each camera, using the Zony 55mm f/1.8 lens in single-shot AF mode. Drive set to single shot to get all 13 bits. ISO 100. 1/125 @ f/6.3. I… [Read More]
Comparing sharpness in cameras with different-sized sensors
A few posts ago, I showed you the results of running slanted-edge modulation transfer function tests on the Sony a7 and a7R, both handheld. Since the cameras have different resolution, and the test results for MTF50 were in terms of cycles/pixel, I multiplied the a7R values by 1.22 so that the MTF50 results were in… [Read More]
The intellectual underpinnings of MTF analysis for handheld images, part 2
Actually, this post applies to MTF analysis in general, whether the camera is on a tripod or not. In the previous post, I said: to get the system’s modulation transfer function (MTF), we perform a Fourier transform on the system’s impulse response, or point-spread function (PSF), and throw away the imaginary part. What do we… [Read More]