For this exercise I am required to take similar shots of, for example, a busy street/market on an overcast day, and vary the ISO – starting at a normal level i.e 100 and increasing it to a high sensitivity for example 400, or 800. Then enlarge these shots using digital software and compare the same area in each photo and log the results.
Going by what I have already learnt about ISO levels, I am expecting the ‘noise’ or grainy-ness to increase as the ISO increases.
I used a fixed aperture of 5.6 for this exercise and used the full range of ISO settings 100, 200, 400, 800, 1600 and 3200. (My results may be more subtle due to this, but i wanted to use all settings available.)
As you can see from the images above – there is no significant difference throughout any of the ISO settings.
It is only when you zoom in on a specific detail that the difference in ISO becomes apparent.
I’ve zoomed in on an object that is in the far distance – it is the ariel on the side of the beige building. You can clearly see the gradual progression of ‘noise’ that appears as the ISO is increased. In the last picture shot using an ISO 0f 3200 the grainy-ness is clearly evident, especially in the leaves of the tree.
I would like to experiment more with ISO settings especially in relation to shutter speed. During this exercise, because I was using aperture priority mode my Nikon adjusted the shutter speed in accordance to the ISO. I will try this exercise while in manual mode so I can have complete control over aperture, shutter speed and ISO.
My results will be on the blog soon.