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A stupid question about camera processing.
Dec 18, 2015 17:25:53 #
If I shoot a pic at 1/350th of a second I see it immediately on the back of the camera.
Today I was shooting at 20 seconds.
after the 20 seconds ended it seemed like another 30 seconds for it to show up on the back of the camera.
why does that take so long to process a shot like that?
I would think that once the sensor recorded the image,
it would be the same as any other image and process just as fast.
I am shooting RAW ( in case you ask)
Today I was shooting at 20 seconds.
after the 20 seconds ended it seemed like another 30 seconds for it to show up on the back of the camera.
why does that take so long to process a shot like that?
I would think that once the sensor recorded the image,
it would be the same as any other image and process just as fast.
I am shooting RAW ( in case you ask)
Dec 18, 2015 17:29:24 #
bdk wrote:
If I shoot a pic at 1/350th of a second I see it immediately on the back of the camera.
Today I was shooting at 20 seconds.
after the 20 seconds ended it seemed like another 30 seconds for it to show up on the back of the camera.
why does that take so long to process a shot like that?
I would think that once the sensor recorded the image,
it would be the same as any other image and process just as fast.
I am shooting RAW ( in case you ask)
Today I was shooting at 20 seconds.
after the 20 seconds ended it seemed like another 30 seconds for it to show up on the back of the camera.
why does that take so long to process a shot like that?
I would think that once the sensor recorded the image,
it would be the same as any other image and process just as fast.
I am shooting RAW ( in case you ask)
long exposure noise reduction?
Dec 18, 2015 17:32:05 #
20 seconds is a lot of information to process.any changes in light and movement are also captured.
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Dec 18, 2015 17:36:00 #
does the camera do noise reduction on its own? Ive never seen anything in the book about that.
Dec 18, 2015 17:36:04 #
Depends in part on what camera you have.
Some have long exposure noise reduction (NR), some have high ISO NR, some combine both together.
When you shoot slow speeds, the sensor creates more heat and introduces more noise. To counteract this, after you shoot the processor fires a "blank" of the same length to try to duplicate the sensor condition and then remove the noise from the original.
To avoid this turn noise reduction off and deal with it in post processing, which is as good or better.
Some have long exposure noise reduction (NR), some have high ISO NR, some combine both together.
When you shoot slow speeds, the sensor creates more heat and introduces more noise. To counteract this, after you shoot the processor fires a "blank" of the same length to try to duplicate the sensor condition and then remove the noise from the original.
To avoid this turn noise reduction off and deal with it in post processing, which is as good or better.
Dec 18, 2015 17:37:05 #
Offhand, I would agree with oldtigger that you have long exposure noise reduction enabled. You can look it up in the manual.
Dec 18, 2015 18:30:51 #
corryhully wrote:
20 seconds is a lot of information to process.any changes in light and movement are also captured.
That, in my opinion, would be the most logical answer as the buffer fills and then needs to be processed before the camera renders the resulting capture.
The best folks to answer this should be found in astro-photography as they understand this process much better (check the forum section and ask there?).
(oh by the way... This proves that a raw IS a processed capture!!! :shock: :twisted: :mrgreen: :XD: :lol: :lol: :lol: )
Dec 18, 2015 19:46:50 #
Rongnongno wrote:
That, in my opinion, would be the most logical answer as the buffer fills and then needs to be processed before the camera renders the resulting capture.
The best folks to answer this should be found in astro-photography as they understand this process much better (check the forum section and ask there?).
(oh by the way... This proves that a raw IS a processed capture!!! :shock: :twisted: :mrgreen: :XD: :lol: :lol: :lol: )
The best folks to answer this should be found in astro-photography as they understand this process much better (check the forum section and ask there?).
(oh by the way... This proves that a raw IS a processed capture!!! :shock: :twisted: :mrgreen: :XD: :lol: :lol: :lol: )
On a long exposure more noise than usual is captured, so following a 20 second exposure a 20 second dark frame with the shutter closed is captured. subtract the dark frame from the long exposure and much of the noise is removed. Some camera's do it after every long shot. Others capture a single dark frame, and use it against all the long frames.
Dec 18, 2015 19:55:04 #
Rongnongno wrote:
That, in my opinion, would be the most logical answer as the buffer fills and then needs to be processed before the camera renders the resulting capture.
The logical answer is not always correct. If that was true we could not shoot 4 or 6 frames per second with noise reduction off either. Buffer speed is not the same as processing speed. At a 20 second exposure, noise reduction off, the camera is instantly ready for another shot after 20 seconds, not 40.
Dec 18, 2015 20:46:24 #
OddJobber wrote:
.../...
And this where you get lost...
For 20 seconds the camera registers the data then it needs to process it in order to create a capture (how long does this take? Heck if I know). It has nothing to do with FPS.
Since I am not sure I indicated that it is an opinion.
There is absolutely no indication that the op is using in camera NR seeing his surprise at that question.
I also refer the op to a forum section where long exposure is basically the norm as I assume (again an opinion) that they very likely know more.
Dec 18, 2015 21:46:14 #
kavner58
Loc: Portland, Oregon
Rongnongno wrote:
b And this where you get lost... /b br br For 2... (show quote)
It is a feature to reduce what is called "dark noise". For long exposure time, there is some fixed noise integrated in the sensor. Say you set the exposure time to 5 seconds, noise reduction on, the camera takes your image with shutter open for 5 sec, then spends another 5 sec with closed shutter, and it takes very short time to subtract the dark noise from the first image. Again, this is not a matter of opinion - it is a feature of my Nikon D7100 and I am sure many other cameras. Just read your instruction manual...
-AK
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Dec 18, 2015 22:01:39 #
We need to know what camera is being used to learn...
What you mention exists in my D800e. I was not aware of it.
What you mention exists in my D800e. I was not aware of it.
Dec 19, 2015 04:36:59 #
OddJobber wrote:
The logical answer is not always correct. If that was true we could not shoot 4 or 6 frames per second with noise reduction off either. Buffer speed is not the same as processing speed. At a 20 second exposure, noise reduction off, the camera is instantly ready for another shot after 20 seconds, not 40.
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Dec 19, 2015 05:14:24 #
Rongnongno wrote:
And this where you get lost...
For 20 seconds the camera registers the data then it needs to process it in order to create a capture (how long does this take? Heck if I know). It has nothing to do with FPS.
For 20 seconds the camera registers the data then it needs to process it in order to create a capture (how long does this take? Heck if I know). It has nothing to do with FPS.
Time spend collecting photons is unrelated to time spent processing sensor data. The maximum Frames Per Second that a camera can shoot is a very exact measure of how fast sensor data can be processed. For a camera that can shoot at 5 FPS it takes 0.2 seconds to process the data per shot. That is the same speed and the same amount of data for an image with a shutter time of 1/8000 second or 30 seconds.
Rongnongno wrote:
Since I am not sure I indicated that it is an opinion.
There is absolutely no indication that the op is using in camera NR seeing his surprise at that question.
There is absolutely no indication that the op is using in camera NR seeing his surprise at that question.
There is every indication that NR is being used. There is no other way that a 20 second exposure would require 40 seconds before the camera is ready for the next shot. The only way to take 20 seconds longer is not due to processing data, but instead is the result of collecting data for 20 seconds longer.
Dec 19, 2015 05:27:11 #
As someone who's accidentally turned "Long exposure noise reduction" on and had this happen to them (and then turned it right back off) I can make a good guess that that's what's happening here.
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