DPP Exercise7- Your tolerance for noise

I have 21 ISO settings on my camera (ignoring 'Auto') ranging from 100 to 25600. I placed the camera on a tripod, set the camera to aperture value at 6.3, disabled the noise reduction facility and worked my way through the ISO settings one by one. All images were shot in RAW. I then downloaded the images on to my computer saving them as DNG files and examined them in Photoshop without any further enhancement  other than the default values used in the RAW conversion software.

I viewed each image at 25%, 50% and 100% zoom values to see at what point noise became a problem.

Noise was not evident at any zoom level until the ISO value was at 500. At this value it was just noticeable at 100% but in my opinion was not a significant problem. At ISO 800 noise was just noticeable at 50% and noticeable at 100% and this time at 100% I would judge it to be a nuisance. Noise became noticeable at all zoom levels at ISO 2000 with noise at 100% being unacceptable. From this point on noise became significant at all zoom levels until at 25600 it was the dominant factor in the image on pale areas of a similar colour and unacceptable in all other areas.

The results were as I expected with the lowest ISO's providing the least amount of noise. I feel that the point at which noise becomes a problem will vary from image to image depending upon the light and the tonal range and the size at which the image is viewed and/or printed. In the images that I took there was large areas of similar pale colours and these seemed to suffer the most. Shadows and areas where there was patterns or colour changes as in a carpet was less of a problem.

The viewing and/or printing size is also relevant with experience suggesting that the printed version is more tolerant of noise.

Lessons learnt - I have always used the noise reduction system of the camera with successful results up to an ISO of 6400. Although I have used both the higher settings (12800 and 25600) when faced with either accepting the problem of noise or not getting the picture I have had mixed results. Again this seems to depend upon the range of the image and whether there are any large areas of a similar colour.

As always with these exercises I have learnt something more about my camera. In this case it was about the noise reduction facility and how this can be used to reduce noise to an acceptable level.

I decided against including images in this blog as the noise does not show in the small images that are on the blog.