Long exposures and noise
Discussion
I was out taking some shots last week in the moonlight. Got back and whilst thawing out i downloaded the pictures, only to find the visual equivalent of a spinal tap gig. Atrocious irrepairable noise on every shot. I was taking 20 to 30 second exposures on various ISO settings from 100 through to 400, various appertures from 1.8 through to 15 or so. Now before i go and freeze various parts of my anatomy off trying again, i need some pointers as to what the problem is.
a) My D30 (the old one) is just rubbish and will do this on all long exposures
b) Even strong moonlight just isn't enough light
c) Something else
Can upload a few of the shots if it would help a diagnosis.
a) My D30 (the old one) is just rubbish and will do this on all long exposures
b) Even strong moonlight just isn't enough light
c) Something else
Can upload a few of the shots if it would help a diagnosis.
That last shot has a similar quality to an old Edward Steichen print that I saw some years go at the V&A. I cannot remember the process. Will investigate further and post details. I think it was called 'Moonlight'.
What you have is indeed noise and that is a product of low level light, long exposures. Nothing you didn't know already I know. I'd have a look at the different channels and see which is least/most noisy and just have a play with curves and levels. You may be able to mask (nothing to do with sharpening
) the fringing by adjusting curves and levels in the offending channel. If you use adjustment layers you can keep a record of each individual change and then transfer the appropriate adjustment layer/layers to other files in the series to save yourself a lot of extra work and time.
What you have is indeed noise and that is a product of low level light, long exposures. Nothing you didn't know already I know. I'd have a look at the different channels and see which is least/most noisy and just have a play with curves and levels. You may be able to mask (nothing to do with sharpening
) the fringing by adjusting curves and levels in the offending channel. If you use adjustment layers you can keep a record of each individual change and then transfer the appropriate adjustment layer/layers to other files in the series to save yourself a lot of extra work and time. Edited by EmmaP on Tuesday 7th November 00:26
Not sure if all cams do this but the D70 and D2X (perhaps other Nikons) both have a gizmo that you can configure to reduce l o n g exposure noise . . . it takes the first image with the shutter open (obviously) then takes a second image with the shutter closed then subtracts the second from the first . . . hence removing noise caused by the sensor itself (thermal noise usually - and hot pixels) . . . works very well in my experience . . . only downside (obviously) is that it doubles any long exposure time as the camera is effectively disabled when it's doing the second exposure . . .
I took this with it . . . with the camera balanced on a case of beer . . .
One of my objectives this winter is to do some night time photos up in Glencoe . . . snow, starlight and a big feck off heater in the car to warm up in . . .
funky
Fd
I took this with it . . . with the camera balanced on a case of beer . . .
One of my objectives this winter is to do some night time photos up in Glencoe . . . snow, starlight and a big feck off heater in the car to warm up in . . .
funky
Fd
fergusd said:
Not sure if all cams do this but the D70 and D2X (perhaps other Nikons) both have a gizmo that you can configure to reduce l o n g exposure noise . . . it takes the first image with the shutter open (obviously) then takes a second image with the shutter closed then subtracts the second from the first . . . hence removing noise caused by the sensor itself (thermal noise usually - and hot pixels) . . . works very well in my experience . . . only downside (obviously) is that it doubles any long exposure time as the camera is effectively disabled when it's doing the second exposure . . .
I took this with it . . . with the camera balanced on a case of beer . . .
One of my objectives this winter is to do some night time photos up in Glencoe . . . snow, starlight and a big feck off heater in the car to warm up in . . .
funky
Fd
I took this with it . . . with the camera balanced on a case of beer . . .
One of my objectives this winter is to do some night time photos up in Glencoe . . . snow, starlight and a big feck off heater in the car to warm up in . . .
funky
Fd
Have to say, cool use of beer, but at that time of night camping should the case not have been empty.
On the subject of the long exposure noise reduction, i tried a couple of shots when i first got my 30D, not knowing about it, thought the camera was broken as it had 'locked' up for a while, took it back to the shop, imagine the embarassement.
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