Tolerance for noise

It took a while to find a picture situation which fulfilled the criteria of daylight indoors and a combination of sharp detail and a textureless area. The idea was to take a series of identical photographs changing the ISO setting from one to the next using all the ISO camera settings. Using a tripod I came up with the following images.








P508: f5.6 @ 1/3  ISO 100 37mm



P508 : enlarged image

I decided to enlarge a section of the first image shot at ISO100 as a starting point for comparison with alter images taken at higher ISOs. Looking at the various later images, I could not see signs of noise until the ISO rose to 800 onwards... 





P509: f9 @ 1/3  ISO 200 35mm



P510: f7.1 @ 1/10  ISO 400  35mm



P511: f8 @ 1/15  ISO 800  35mm


Graininess starts to show..



P512:  f11 @ 1/15  ISO 1600  35mm




 

P513:  f16 @ 1/15  ISO 3200  35mm




P513 : enlarged image 

Here the noise is very apparent in the enlarged image, particularly in the straw hat / wood grain area  and white wall; coloured speckles being most apparent....some of the 'gold' speckling on the hatband though is the natural play of light on the slightly shiny material.





P513:  image taken without in camera noise reduction

Thought that it would be interesting to compare the last image taken at the highest ISO sensitivity with a second image taken using the same settings but with the in camera noise reduction disabled to see the extent of noise and how it appeared. You can see the noise is more obvious in the close up; variations of green and red speckles on the dark hatband  and white fabric.They are also very obvious on the plain textureless wall behind the hat.

Interestingly, this exercise while showing how noise increases with higher sensitivity settings does show me how difficult it is to differentiate noise from bona fide texture sometimes.