by ʇolɐǝz ǝɥʇ qoq

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What happens if you attempt to operate a Sony SLT (pellicle mirror) camera with the mirror up? Does the camera detect this condition? Will the camera shoot? What happens to autofocus--can the camera fall back to contrast detection? Is the increase in exposure value accounted for?

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Are you sure that it can be operated with the mirror up? I thought the whole point of these cameras was that the mirror never moved. That said I don't own one and can't find the manual for one online to check. – Dan Jan 6 '12 at 9:36
The mirror must be moved manually, there is not motor to move it but it is movable by hand so that the sensor can be cleaned. It is a wonder why they did not simply produce a completely sealed unit which would prevent dust from reaching the sensor. I suspect the issue be with the sensor-shift stabilization system but that is just a guess. – Itai Jan 6 '12 at 17:41
Keep in mind that the focal-plane shutter is a mechanical part which may generate dust behind the mirror. This is probably the reason the unit is not fully sealed. – bwDraco Jan 6 '12 at 17:44
up vote 5 down vote accepted

The SLT-A55 at least no longer focuses but everything works, even with the mirror removed which you can do without too much difficulty. Exposure is off by about 1/3 EV.

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