Noise Reduction

[Martin 2]

Anyone have any thoughts on the noise reduction setting on my camera (coolpix 4300 ). If I have this turned on and take say a 30 sec ex. it takes about a minute for the camera to process the image to the card, would I be better off turning this feature to off. and using PS to adust the image.

M2

[OXO]

From my experience of the (Nikon coolpix 4500) turning the noise reduction off would be a deff NO NO as the image degradation would render the images useless even for stacking/processing. The reason it takes a min to do is because it takes an automatic dark frame and subtracts the noise from the initial image away(well most of it)...

James

[Grant]

From my own limited expeience I would go for 'off' and processing in PS, the reason being, the camera is probably filtering out stray pixels which could be noise but with astronomy, could just be star points so you would lose some detail. If you leave the noise removal off then at least when you get it to your computer, you've got the natural image that you can work on, if you go for the noise reduction on then you can't re-add in stars and detail that the camera removes....

I'm sure others will know more, I was trying to find out what kind of noise removal the Nikon uses but can't find any details...

[Grant]

From my experience of the (Nikon coolpix 4500) turning the noise reduction off would be a deff NO NO as the image degradation would render the images useless even for stacking/processing. The reason it takes a min to do is because it takes an automatic dark frame and subtracts the noise from the initial image away(well most of it)...

James

Ah, so it takes a dark frame shot... the thing I've never understood about that technique, surely the noise in the sensor is to some extent random, yes there will be some patterns because of temperature and the way the sensor is designed but surely alot of the noise will change constantly, so the noise in the image won't necessarily be the same as the noise in the dark frame...

[OXO]

Leaving the Noise Reduction off will induce Stars not remove them Grant

[Grant]

Yeah, it will leave noise in but surely its better to leave it in and then remove the noise later than to remove it and possibly lose some stars as well? Better to have false negatives than false positives? I admit I know very little so am more than likely to be wrong

[OXO]

Ah, so it takes a dark frame shot... the thing I've never understood about that technique, surely the noise in the sensor is to some extent random, yes there will be some patterns because of temperature and the way the sensor is designed but surely alot of the noise will change constantly, so the noise in the image won't necessarily be the same as the noise in the dark frame...

The reason the Camera takes the frame(Dark) straight after the first image is because it can record those temps and has a balance in which to work out the noise from my understanding of it, temps being the main reason too for taking the dark frame so soon......

[Grant]

Ah, so it takes a dark frame shot... the thing I've never understood about that technique, surely the noise in the sensor is to some extent random, yes there will be some patterns because of temperature and the way the sensor is designed but surely alot of the noise will change constantly, so the noise in the image won't necessarily be the same as the noise in the dark frame...

The reason the Camera takes the frame(Dark) straight after the first image is because it can record those temps and has a balance in which to work out the noise from my understanding of it, temps being the main reason too for taking the dark frame so soon......

Yeah that makes sense but there is still an element of random in there, in that it will not remove all of the noise just the more regular patterns of noise.... nitrogen cooled CCD chips here we come

[OXO]

Yeah, it will leave noise in but surely its better to leave it in and then remove the noise later than to remove it and possibly lose some stars as well?

To a certain extent that is true if you know the 100's or 1000's of stars positions in the none DE noised images but it takes too long to process. Agreed it would make far better images for scientific purposes but people just don't want to take that long over processing etc etc...

James

[OXO]

Yeah that makes sense but there is still an element of random in there, in that it will not remove all of the noise just the more regular patterns of noise.... nitrogen cooled CCD chips here we come

Correct this is why some people use ICE PACKS the sort you get from supermarkets for taking on picnics to keep things cool n fresh, wrap em round the camera and thus cooling it down and ridding some elements of noise..

[Martin 2]

When we get some clear nights I,ll do a test for both on and off, and see which is better, I'll post the results.

Thanks for the imput.

M2

[Kaptain Klevtsov]

The noise reduction works as most CCD chips have pixels that sort of leak, i.e. they fill up on their own. As this typically takes a second or two nobody cares for cameras. When you get to do long exposures it becomes necessary to take a shot, then take a shot with the shutter closed and subtract the second from the first. That way the noisy pixels (not at all random) get sorted out.

HTH

Captain Chaos

[geppetto]

On my Coolpix 5400, I always leave noise reduction on.

Did lots of trials last year and on is much better.

Only ever use ISO 50 or 100 for the same reasons.