when do you use noise reduction?

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sdd

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I normally do noise reduction first and sharpen last ... is this correct?

Using Noise Ninja.
 
I make adjustments first (WB, colour, etc) - then noise reduction (exporting from Aperture to PS) - then when I'm back in Aperture sharpening.
 
My 40D has in-camera noise reduction but I only use that for astrophotography and it makes a big difference.
 
My 400D only has Long exposure NR but I've made sure to disable that.
 
koffiejunkie said:
Why? Dark pixel subtraction does not edit pixels like High-ISO NR does.
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Time. I only generally make long exposures when I'm shooting lightning and as we both know if you take a 30 second exposure you have to wait another 30 seconds for it to take the dark frame.

Since noise is usually predictable I can always take a dark frame at a later stage and do it in photoshop.
 
Never - Noise is awesome. Adds character and charm to otherwise ordinary pics.
 
NeatImage does a much better job of noise removal and has a lot more control than any other noise removal app I have ever used and I have used them all.

If you ever want to break into stock photography noise is your worst enemy and your images will be rejected immediately for noise. To answer the original question, you only do noise removal when you think it is necessary, don't listen too much too people on photography forums they tend to make a LOT of noise about noise.

If you expose your image correctly in camera your noise will be mininal or zero, that is the key. I have many images taken at ISO 3200 and above that have minimal noise and others shot with the same high iso's that have noise like snow storms.

LongExposure NR is an absolute waste of time, turn it off, it can quite easily cost you a shot while the camera is (doing a poor job) processing the image.
 
bwana said:
Since noise is usually predictable I can always take a dark frame at a later stage and do it in photoshop.
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I didn't know you could do that :) Then again, the only time I do exposures long enough to warrant long exposure NR is when I'm taking night time cityscapes/buildings/etc where I'm not going to miss a shot while waiting. Letting the camera handle that makes more sense to me than dicking around in PS and ending up with an extra 60MB file.

threegee said:
If you expose your image correctly in camera your noise will be mininal or zero, that is the key.
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Your chroma noise will be minimal. But yeah, +1 for correct exposure.

threegee said:
LongExposure NR is an absolute waste of time, turn it off, it can quite easily cost you a shot while the camera is (doing a poor job) processing the image.
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Depends on your camera.
 
koffiejunkie said:
I didn't know you could do that :) Then again, the only time I do exposures long enough to warrant long exposure NR is when I'm taking night time cityscapes/buildings/etc where I'm not going to miss a shot while waiting. Letting the camera handle that makes more sense to me than dicking around in PS and ending up with an extra 60MB file.
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You can always test your sensor by taking a dark frame.
 
bwana said:
You can always test your sensor by taking a dark frame.
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For hot pixels? Yeah. I don't know if it's consistent though - I've never had a hot pixel myself, and none of the reviews on the 40D that I have read have found any either. But it doesn't bother me to spend a little extra time to be sure. Most of my long exposures are under 5 seconds, anyway, so it doesn't eat up too much time.
 
Depends on your camera.
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Have used this function on several different camera's over the years. If you shoot raw, that function is actually meaningless anyway and you can do much better NR using the right software.
 
koffiejunkie said:
For hot pixels? Yeah. I don't know if it's consistent though - I've never had a hot pixel myself, and none of the reviews on the 40D that I have read have found any either. But it doesn't bother me to spend a little extra time to be sure. Most of my long exposures are under 5 seconds, anyway, so it doesn't eat up too much time.
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You'll probably only ever start seeing hot pixels when you run into exposures of 10 minutes and above, even the highest "flag ship" models will reveal hot pixels with very long exposures albeit slightly less than the lower end models.
 
threegee said:
Have used this function on several different camera's over the years. If you shoot raw, that function is actually meaningless anyway and you can do much better NR using the right software.
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This may differ from camera to camera. On the 40D, long exposure NR is applied to the RAW, but high ISO NR is applied only to JPEG. I'm not convinced about the post solutions. I haven't seen anything that's better than what I get out of my camera. I continue to try, but so far the money I spent on NR software is waisted.

threegee said:
You'll probably only ever start seeing hot pixels when you run into exposures of 10 minutes and above, even the highest "flag ship" models will reveal hot pixels with very long exposures albeit slightly less than the lower end models.
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Did several back-to-back shots of stars - 30 minute exposures. I switched all NR off because I didn't know if the batteries would make it, it was pretty cold anyway. Didn't get a hot pixel anywhere.
 
koffiejunkie said:
Did several back-to-back shots of stars - 30 minute exposures. I switched all NR off because I didn't know if the batteries would make it, it was pretty cold anyway. Didn't get a hot pixel anywhere.
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What did you use to track the stars with?
 
koffiejunkie said:
This may differ from camera to camera. On the 40D, long exposure NR is applied to the RAW, but high ISO NR is applied only to JPEG. I'm not convinced about the post solutions. I haven't seen anything that's better than what I get out of my camera. I continue to try, but so far the money I spent on NR software is waisted.



Did several back-to-back shots of stars - 30 minute exposures. I switched all NR off because I didn't know if the batteries would make it, it was pretty cold anyway. Didn't get a hot pixel anywhere.
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I've done numerous tests with NR on and off and the differences in the final image are imo not worth that extra wait, I also get flawless results with the correct NR software.

As for the hotpixels, I did not elaborate, depends on the aperture used, very small apertures with long exposures in low light will reveal them. I have many 30+ minute exposures with not a speck.
 
threegee said:
I've done numerous tests with NR on and off and the differences in the final image are imo not worth that extra wait, I also get flawless results with the correct NR software.
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If I get to the point where it takes me less time to open the image in PS/Noise/Ninja/DFine/etc and apply the NR than it takes me to wait for the dark frame, I'll take it more seriously. But I'm dead happy with the results I'm getting from the camera.

threegee said:
As for the hotpixels, I did not elaborate, depends on the aperture used, very small apertures with long exposures in low light will reveal them. I have many 30+ minute exposures with not a speck.
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f/16 at 1800 seconds should do it? Maybe I'm just lucky :)
 
koffiejunkie said:
I didn't track the stars. I was doing star trails :)
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I think I'll have to give that a go. If I was going to shoot the horizon would facing north (or south) give crescent/arc shaped trails?
 
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