Questions tagged [dark-frame-subtraction]

A method of reducing 'fixed pattern noise' and the influence of 'hot pixels' by taking a frame with the shutter remaining closed and subtracting the results from a frame previously taken with the shutter open.

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4
votes
1answer
128 views

Why does a non-linear relationship exist between noise level (of dark frame) and ISO setting

According to Does changing the ISO of a modern digital camera really change the gain of an electronic amplifier?, the ISO physically amplifies signal in analogic way, so it is more effective than ...
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3answers
1k views

How to remove hot pixels with a dark frame?

I took some photos at night and I didn't have long exposure noise reduction on. My photo has quite a few hot pixels, here's a 100% crop of a part of the sky: Since long exposure noise reduction is ...
2
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1answer
269 views

How does in camera dark frame noise reduction work?

There are several questions and a tag relating to what it is but I can't find much relating to how it is actually done in camera anywhere. The internet reveals many "how to" pages for doing the ...
2
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3answers
334 views

What should I look for in a camera for shooting in bulb mode for astrophotography?

I am interested in astrophography and I would like to learn and experiment with long exposure. I have been looking around for some dslr cameras but I can't find much information about bulb mode for ...
0
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1answer
147 views

At what exposure times do fixed pattern noise become apparent?

I have been studying into photographing the night sky. I have subsequently come to learn of the technique of dark frame subtraction to reduce fixed pattern noise. So I am curious as to what is the ...
11
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2answers
2k views

Why does my Canon 700D take so long processing when I take a long exposure? [duplicate]

I am trying to get into long exposure time lapse photography, and was wondering if there was a way of speeding up or turning off the processing of the image! When doing long exposure time lapse at (...
3
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2answers
165 views

Black level unchanged after long exposure noise reduction

I took 2 raw photos with the lens cap on: One with Long Exposure Noise Reduction turned on, one with LENR turned off. Checking the tags in the Raw file, BOTH report black levels of [200, 200, 200, ...
3
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2answers
494 views

Long exposure shots showing huge bright spot. What happened to my sensor?

Recently I noticed the appearance of a quite big spot of increased brightness and strange colour in my longer exposure photos. I'm using a Samsung NX300m (I know, not a good camera for low light...). ...
0
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2answers
1k views

Astrophotography exposure setting for noise reduction

I was on a hiking for a week into the dense forest of Western Ghats with my Sony slt a58. I am into Astrophotography. The place was absolute black with millions of stars. The perfect place for ...
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2answers
7k views

How to prevent hot pixels? [duplicate]

I've just returned from a trip. One of the locations was very dark site. I took a photo with 4 minutes exposure for the foreground. The photo came out unusable. There are so many red, green, and ...
7
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1answer
1k views

What's the best way to deal with hot/stuck pixels in long exposure night photographs?

I discovered red/blue/white pixels on my night photographs tonight. Trying to confirm this, I took a black image with the lens on and indeed I saw a whole lot of them (I didn't count them but at least ...
2
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1answer
3k views

Should I turn off in-camera long exposure noise reduction when shooting for image stacking?

I have never shot with intervalmeter for the purposes of image stacking but want to at least try. I am going to try star trails but my question is this: Should I turn off in-camera long exposure ...
3
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3answers
581 views

Is there any quality advantage to doing dark frame subtraction in camera?

Is there any quality advantage to doing dark frame subtraction in camera? It seems to me that doing it manually in software can't be any worse, and can be better by using a dark frame that is the ...
5
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2answers
280 views

Why does raising ISO make image quality appear lower even though my measurements suggest it shouldn't?

I know this may be rehashing one of the most discussed topics, but I would like to take it a slightly different direction and solicit input. First of all, I am familiar with the electrical ...
7
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2answers
737 views

Do low ISO photographs need Long Exposure Noise Reduction?

I usually took long exposure photo with ISO 100, so do I really need to turn on Long Exposure NR on? It really take time for processing.
0
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1answer
967 views

Unexpected behaviour of interval shooting with Nikon D5100 [duplicate]

I want to do some star trail and time lapse shoots this weekend and I have for the first time been looking into the interval shooting option on the Nikon D5100. I already understood that the interval ...
33
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3answers
12k views

Why does storing a long exposure photo take almost as long as the exposure time itself?

Last night I took some night sky shots, and I've noticed that with long exposure times (15s, 30s) the time it took to store the images in the camera memory card (jpeg) took roughly as long? The ...
4
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3answers
773 views

Why is dark-frame subtraction on my Pentax camera shorter than the exposure time?

When my Pentax K-r applies long exposure noise reduction (dark-frame subtraction), the processing time required for this operation is less than the exposure time. For example, my camera may perform ...
15
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5answers
12k views

Does “long exposure noise reduction” option make any difference when shooting RAW?

I can configure my camera (5D) to use long exposure noise reduction (dark frame is exposed and subtracted), but is this method really effective when shooting RAW? Or is the actual subtraction only ...