dclark
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 Re: A7rV for BIF? More recent af vs stacked sensors | |
Photosection wrote:
Why are Sony insisting on limiting their 7 series cameras electronic shutters to 1/8000th though. Just the simple task of shooting a very fast lens wide-open like the 50GM/1.2 (for visual effect) becomes problematic on a 7 series body on say a sunny beach (think fashion).
The reason for the limitation may be that the width of the exposure slit between the first curtain and second curtain gets to be too narrow. The A7R4 (and presumably the A7R5) second electronic curtain can traverse the sensor in about 108 msec = 1/9.25 sec (see page 1 and 4 of this thread, https://www.fredmiranda.com/forum/topic/1663827/0). Since the cameras have ~6446 rows that means the shutter moves at a rate of ~58,600 rows/sec. So for a shutter speed of 1/8000 sec the number of rows between the first and second curtain is about 7 rows. For the A1, the second electronic curtain traverses the sensor in about 1/237 sec. There are 5760 rows, so that is 1,343,790 rows/sec. The fastest shutter is 1/32000 sec, which means the width of the shutter slit is about 42 rows. The A1 reads out rows in groups of 12, so I assume it is actually 48 with the first and second curtain steps offset by half the step interval.
7 rows is a pretty narrow shutter slit, so any slight timing variation will cause exposure variation. My guess is Sony does not want to run a narrower shutter slit.
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