No - I think you may be missing my point (as I didn't explain it very well) - if anything I think a modern compact should have a speed advantage over a traditional DSLR mechanical shutter.
AF time shouldn't enter into it as when you've half pressed the button that part of the "computation" is "done with" - and the actual, "capture" of the frame image from the sensor to the buffer should take mlliseconds - any "other processing" happens afterwards and may affect burst rates etc. but not single shot capture...
Jim
Compact cameras still have a mechanical shutter but with a fixed lens it's not the larger focal plane shutter in a DSLR and instead is in the lens, often the part of the aperture system itself when I've looked (difficult to tell when compacts have such tiny aperture openings though). A compact has a longer shutter cycle because it has no OVF and has to use the sensor, when you fire off a DSLR conventionally (not using liveview, using the OVF) the shutter opens, exposes the sensor then closes and the exposure is complete. On a compact camera, the shutter is always open to generate the live feed so for an actual exposure it has to first close the shutter, open the shutter for the actual exposure, close it again to finish the exposure and re-open it to resume the liveview.
You should be able to test this yourself, on the LX3 for example if I set an F8 aperture and a slow exposure (say four seconds) then look down the lens I see the following sequence:
1 - aperture blades close completely (effectively shutter closed or something beside the aperture blades, all very small)
2 - aperture blades re-open slightly to F8 (shutter open)
3 - two seconds later the aperture blades close right down again
4 - aperture blades re-open.
This is one of my annoyances with the mirrorless cameras as they have the same issue but with a large focal plane shutter instead, they also have to close the shutter, re-open, close, re-open. Panasonic seem to have improved this quite a bit in the GH2 but you still get that bit of lag which is particularly noticeable alongside the D700 which takes a picture pretty much the instant you squeeze the shutter release. Oddly while the GH2 does have an electronic shutter for its 40fps mode, you can't seem to use this for normal shots to get a silent exposure. As far as I'm aware there are some other electronic shutters but most fixed lens compacts still use a central shutter design but could be wrong on that, it's not something I see discussed very often.
John
