In camera noise reduction and RAW images

[gad-westy]

There seems to be conflicting info on this. I shoot raw and then upload my images into Aperture 3.

Given the above, is there any point in me using either long exposure Noise reduction or high iso noise reduction?

 

[neil_g]

depends if you want the camera to use what it thinks is right for the noise reduction or whether you want to retain control of this yourself in PP.

 

[badboy1984]

personally i tend to leave anything off on my camera and just shoot RAW and leave all the post edit afterwards in lightroom or photoshop etc.

 

[ausemmao]

Long exposure NR will affect the RAW, High ISO NR won't (different methods of NR to counteract different things).

 

[arad85]

Long exposures with DSLRs is very well explored in the astrophotography field where you really are eeking out the most from a very low signal. There you take a number of different types of images (lights, darks, bias and flats) which each help reduce a different type of noise which is very important when dealing with very low signal to noise ratios.

Long exposure NR is the equivalent of 1 light + 1 dark from the astrophotography world and is there to reduce the thermal noise/hot pixels in the camera and works by taking an image with the shutter closed (which maps what the sensor is doing only). It has to be done at the same settings and temperature as the original image and cannot be replicated in post. If you have the time to do this, it is worthwhile.

High ISO NR is just a different way of processing and is probably better done in post where you can be more selective about what gets blurred away.

Bottom line, LENR: yes, HINR: no.

 

[arad85]

PS. if people are wondering what lights, darks, bias and flats are: http://deepskystacker.free.fr/english/faq.htm#lightdarkflatoffset

 

[gad-westy]

Cheers chaps. So high iso NR sounds pointless for my uses. The long exposure reduction sounds like it may be of use though. Am I right in saying that the camera basically takes a second blank image as a comparison? I suppose there are circumstances when this would be inconvient but I can see its uses.

 

[arad85]

Am I right in saying that the camera basically takes a second blank image as a comparison? I suppose there are circumstances when this would be inconvient but I can see its uses.

Yes and yes. The blank image has the same inherent sensor noise pattern so can be used to get a cleaner image.