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dropman
11-22-2004, 08:02 AM
How does long shutter speed really works? I turned on M mode on my powershot A75, set shutter to 15 sec, F8, Mounted camera on tripod and pressed shutter release button... Then after some time (shutter lag i quite big when using long shutter speeds) when picture was exposed for about 8 sec i turned camera into another direction. I think this movement should blur out my picture but i do not seen almost any blur on my picture!
So, maybe i am wrong, but it seems that it's no matter i use shutter 10 sec or 15. Maybe at the beginning when shutter opens sensor is more sensitive. I am really confused! Maybe i just do not understand how that all stuff with long exposures work?
PLEASE HELP :)

dropman
11-22-2004, 09:28 AM
sorry, problem solved.
It seems that there is BIG lag befor shutter opens, but actually it opens almost with no lag at all... And when i moved camera into another direction shutter was closed already :D

Terracotta
11-22-2004, 10:35 AM
fyi, the second exposure is a blank frame, or a readout of the CCD noise, by subtracting that frame from the first you reduce the noise of the image somewhat.

D70FAN
11-22-2004, 02:00 PM
fyi, the second exposure is a blank frame, or a readout of the CCD noise, by subtracting that frame from the first you reduce the noise of the image somewhat.

I don't think the A75 is quite that sophisticated (dark frame subtraction). But I think dropman has figured it out.

Congratulations dropman... welcome to the discovery channel... fun eh? ;)

dropman
11-23-2004, 11:21 AM
yeah, fun :rolleyes:

Jeff Keller
11-23-2004, 03:36 PM
I don't think the A75 is quite that sophisticated (dark frame subtraction).

I think the A75 does have it, actually...

D70FAN
11-23-2004, 04:23 PM
I think the A75 does have it, actually...

Really... I have seen nothing in the literature (or in the box) that says the camera has active noise reduction. I used an A75 for a couple of weeks as a vacation knock around and read everything available. If it uses DFS then Canon needs to work on the implementation, as the night shots have a fair degree of noise.

I am amazed and I stand corrected.