Originally posted by stevebrot I used to think that until I did (just for kicks) a 4 second exposure with lens off while looking at the sensor. To be honest, I was alarmed.
Steve
I bet that shutter speed is way beyond the specification of the SR system. Maybe something like 10 stops of SR.
Most of the sensor movement is before and after the image is captured, But then it does not matter if the movement is outside the image circle as no image is captured.
---------- Post added 30-06-15 at 19:17 ----------
Originally posted by vonBaloney No it isn't (necessarily). The sensor is moving around in the stationary (relative to the inside of the camera) image circle, that's how it works. If it was guaranteed to be in the center, that's the same as not moving at all, i.e. no SR.
The sensor start moving when the shutter is pressed and during the mirror is moving it accelerates and is positioned to be able to capture the image centered over the image circle. If it moves 4/10 mm during exposure it will be moving +- 2/10 mm outside of the image circle.
---------- Post added 30-06-15 at 19:24 ----------
Originally posted by romay That's remarkable, because it's rather trivial to find out:
Take any stabilized body + manual lens, dial in a long focal length, take off the lens and see how far the sensor moves when you tilt the body. Scale this up to FF and you pretty much know how big your image circle needs to be.
I tried it and it's much much more than fracions of a milimeters. Actually, it's quite impressive how quick and far that thing can move.
Also, you can try the composition adjust feature of the later bodies to get an idea how far off-center that sensor can shift.
This is not really relevant as the sensor is moving during a much longer time than the SR system support.
Let say the focal length is 400 mm and you need 1/400s shutter speed to get a pixel sharp image without SR, the 3-4 stops of SR would be during 1/25 - 1/50s. How much is the sensor moving during that time?
The composition adjust feature might not be possible on a FF DSLR. Or maybe not support as much movement as on APS-C