For this exercise I have to take a series of identical photographs indoors in daylight of a scene that included some sharp detail and a textureless area like a white wall with some of the textureless area in shadow.
I had to set the camera on a tripod, use aperture priority setting to keep the depth of field consistent and take a series of images covering the whole range of ISO settings on my camera.
My Nikon D5500 ISO range is as follows:
100, 125, 160, 200, 250, 320, 400, 500, 640, 800, 1000, 1250, 1600, 2000, 2500, 3200, 4000, 5000, 6400, 8000, 10000, 12800, 16000, 20000 and 25600.
I’ve chosen to upload several pictures throughout the sequence, rather than the whole sequence.
At the lowest ISO there is no noise whatsoever.
At 500 the noise levels are still hardly present at all.
At 2000 the noise is starting to become evident.
At 8000 the noise is now extremely noticeable, especially in the shadowed area to the left of the vase.
At 16000 the image is covered with noise, making it appear to be of a much lower quality.
Finally at 25600 it’s totally speckled with noise, really reducing the overall quality. I would not want to submit a picture with this much noise.
I’ve always been aware of the results of using a high ISO but this exercise really did enforce the importance of using the lowest possible, and the unwanted effects of using a high ISO. For this exercise I think anything over ISO 800 starts to show an unattractive amount of noise.