There’s a way to look at read noise vs ISO setting that’s different than the curves I presented in yesterday’s post. It’s a bit less intuitive, but, if you can get your head around it, it can give useful insight into how the sensor works. Rather than presenting the standard deviation of the noise in the raw… [Read More]

I made a series of lens-cap shots on the a7S with the ISO set to 12K, the drive mode at single shot, and the shutter speed varied in 1/3 stop intervals from 1/8000 second to 8 seconds: Read noise stays fairly constant as the shutter speeds get longer until about 1/10 second, when it starts to… [Read More]

I’m been showing you histograms of the Sony alpha 7S when making images of the back of the lens cap. We saw some evidence that the chip and/or raw processing was different at different ISOs. I suspect it’s the chip, at moderate ISOs, and processing at nosebleed ones. To get a better look, I measured… [Read More]

Before I get too far into testing a camera, I do a series of exposures calculated to see if there are self-heating effects that might skew my test results. Since many of my tests involve making series of sequential exposures that are later subjected to statistical analysis, material self heating can force me to slow… [Read More]

The Sony a7S is unique among the alpha 7 series in that it has a fully electronic shutter option, called “silent mode”. Here’s the read noise histogram at ISO 400K with the shutter in silent mode and the drive mode set to single shot: The histogram is, to put it kindly, sparsely populated. At ISO… [Read More]