Originally posted by philbaum
One can't separate out the sensor from the other features the camera body has. The Sony IBIS clearly outclasses the K3 SR that i had experience with. The A7r also doesn't have the 5 axis IBIS so i strongly suspect that users have to shoot at higher speeds to get the same sharp images. Sony also included a carbon fiber shutter in the A7rII for much quieter operation and less possibility of shutter shock problems than the A7R.
Pentax learned its lessons on shuttershock with the K7, Nikon with the D800 and Sony with the A7r. But certainly if one keeps the shutter speeds up markedly above 1/100s, it may be hard to see it.
I can't imagine that 42mp versus 36mp is as significant as 5 axis IBIS and a quieter shutter (i.e. less possibility of shutter shock)
For most of my best images I don't use shake reduction, so that's rarely an issue. Even with small birds I look for situations where I can use a two second delay.
In images like this one, I'm not detecting a lack of sharpness due to anything, shot on a tripod, which as far as I know is still what you have to do if you absoutlely have to have the image and need maximum clarity. ....the trouble with comparing IBIS is, how do you create equal circumstances? I don't have a mechanical shake mechanism to create an equal vibration. I guess one can have impressions, based using two systems... or use two systems and then compare images. But it's hard to qualify what that means. You're left with "Some guy says this one is better than that one."
I get good results with SR on my K-3 down to 1/15s, and when pressed have had success down to 1/8s so unless you're saying with a Sony, I could shoot at 1/4 second, it's not two stops better.