I am primarily a landscape photographer, and I like to shoot long exposures in low light situations. One aspect of noise I never see discussed or mentioned is noise related to long exposures. Can anyone give me some idea how the D800 will handle 1 minute, 5 minute, 10 minute, or longer exposures at say ISO 100. This is far more important to me than the noise capabilities at 6400 or higher.

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>Can anyone give me some idea how the D800 will
>handle 1 minute, 5 minute, 10 minute, or longer exposures

At this stage, I think we would just be guessing if we tried to give you an answer

Brian
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I betcha that noise at long exposures is better than my D2H or D2X.

Mel
An Opinionated Old Curmudgeon from Virginia


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But the D2H has BIG pixels man... BIG! I think I'll take mine out and clean it tonight. I cleaned the D2x earlier and I wouldn't want the H to get jealous.

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In all seriousness, can anyone speculate based on the specs that have been published.

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In all seriousness, I do not think this is something that can be speculated about simply looking at specs. What Brian said is spot on. How would one know how effective the D800's long exposure NR is by looking at specs?

Mel
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Long exposure noise is related to thermal implementation - specifically, how fast can they get heat away from the sensor's general physical vicinity. Since none of us have any idea of what the D800 board's layout is, or which of its components generates the heat, it's a sure thing that we don't know how well it will perform in this regard.

Two things to illustrate why we can't tell would be (a) the fact that this is engineered to do video, which generates a LOT more heat than typical still work, and (b) everything in this camera is running at a higher clock rate than in past machines, due to the data rates involved. For the CMOS stuff that is probably in use in this camera, thermal consumption is dependent on clock rate, meaning that at least the data transfer pipeline if not also the processing pipeline are likely to produce more heat than past implementations. On the other hand, they may also run at lower voltage...

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I would imagine that a camera that can record 30 minutes of video should be fairly good at long exposure stills. Without making a huge post, doesn't it make sense that a 10 minute normal still shot is using far less resources than a 10 minute video would and I bet the noise in the video doesn't get worse the closer you get to the 10 minute mark.

This is just my $0.02 and not based on any facts.

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At longer exposures it is more important to do a dark frame subtract, and the question is how repeatable the thermal noise profile is. A dark frame subtract is pretty effective if (for example) you have a brighter corner, but is not good with individual pixels that randomly go hot as noise.

I don't know about D800 itself, but it does bring up the question whether very high resolution (meaning more pixels for a given visible portion) in and of itself with similar noise profiles makes the dark frame more or less effective. Trying to convince myself one way or the other as a thought experiment and not sure. Any astronomers around?

PS. This darm substract is what the long NR setting causes, it takes an exposure while the shutter stays closed, then subtracts it from the exposure with the shutter open. Sort of (it doesn't take exactly the same length exposure, which is the more traditional approach).


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>(it doesn't take exactly the same length exposure, which is
>the more traditional approach).
>
I've found that the NR exposure on Nikon bodies is usually the same as the actual exposure - e.g. if the actual is 30 secs, the NR is also 30 secs.

>>(it doesn't take exactly the same length exposure, which
>is
>>the more traditional approach).
>>
>I've found that the NR exposure on Nikon bodies is usually the
>same as the actual exposure - e.g. if the actual is 30 secs,
>the NR is also 30 secs.

I did quite a bit of testing on my D300, and the longer ones are substantially shorter, don't have it with me now to test but like 30% shorter or more.

Maybe this varies by camera. It was actually a bit disappointing that they didn't do the full exposure, while I guess they could extrapolate, it would seem better to be identical. maybe some models are?


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>
>Maybe this varies by camera.>


I didn't make accurate timings but whenever I used LENR on the D700/D3x the two exposures were around the same length. I never went above 1 minute though so you're probably right for exposures of several minutes.

D3S...

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