Newbie: High speed photos coming as black

whoever

280
IXUS950

Re: Newbie: High speed photos coming as black

« Reply #10 on: 18 / October / 2010, 15:06:12 »

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Quote from: Microfunguy on 18 / October / 2010, 14:51:21

'Bright day' implies the ND filter is in which means that if the ND filter were out the required shutter speed would be about 1/12,800 sec (on most cameras).

Pardon me?

I believe the ND filter is usually 2 or 3 stops (2.86 stops on my cam, for instance), which makes it 1/6400 sec at most. This is indeed a bit over the rim, but still quite safe to use, as image artifacts just start to appear at such speeds.

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Microfunguy

4037

Re: Newbie: High speed photos coming as black

« Reply #11 on: 18 / October / 2010, 16:06:17 »

Quote from: whoever on 18 / October / 2010, 15:06:12

I believe the ND filter is usually 2 or 3 stops (2.86 stops on my cam, for instance), which makes it 1/6400 sec at most.

No, that is two stops, or a factor of 4x.

Three stops is a factor of 8x or 1/12,800 sec.

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reyalp

14118

Re: Newbie: High speed photos coming as black

« Reply #12 on: 18 / October / 2010, 16:13:14 »

Quote from: Microfunguy on 18 / October / 2010, 14:51:21

'Bright day' implies the ND filter is in which means that if the ND filter were out the required shutter speed would be about 1/12,800 sec (on most cameras).

Example:
1/2000th is correct exposure without ND
Camera chooses 1/256th + ND instead, because Tv limit is 1/1600
-> vibration or fast movement is blurry when it doesn't need to be.

I had to work around this exact situation shooting timelapse with sd990 for a moving vehicle.

edit:
You are right, this isn't bright, direct sun. *shrug* problem still exists, solution is still to use modest override, and engage the ND later for really bright scenes.

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Don't forget what the H stands for.

whoever

280
IXUS950

Re: Newbie: High speed photos coming as black

« Reply #13 on: 19 / October / 2010, 12:08:07 »

Quote from: Microfunguy on 18 / October / 2010, 16:06:17

No, that is two stops, or a factor of 4x.
Three stops is a factor of 8x or 1/12,800 sec.

You're right, of course. I must've had a momentary brain blackout.

Still, the question as I perceive it is this: How far can one override the shutter speed, still enjoying predictable exposures and without image artifacts? This is obviously very much hardware-dependent -- foremost, CCD-dependent. In my case, 1/12000 will be correctly exposed, but may have visible image non-uniformity.

I now realize that I've had that override (ND filter always out) activated since I don't remember when, and never noticed ill effects. Of course, it should've been a really bright day indeed...

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