I set out here to take a series of identical photographs where the aim was to see what effect changing the ISO setting on my camera had on the final image. I used the aperture priority setting so that the only thing that would change in the image was the ISO and the shutter speed. The depth of focus would remain the same and the cameras was on a tripod. I shot inside with available natural light so that I would be able to shoot at a high ISo setting (bright sunlight would not have allowed for this). I focussed on a detailed part of the image as I assumed this would be the area to break up with noise once I started shifting up through the ISO settings. Half of the image is a plain white wall and the other half some children’s toys for the detail. They are also slightly in shadow. My camera has seven different ISO settings starting with ISO200 and finishing with ISO12800. I have cropped the original image to make the viewing of the resulting noise more easy to see. I will comment on each ISO setting briefly under the images.
The first picture at ISO200 shows little signs of noise, even in the shadowed areas as I would expect. The text on the car is sharp and clear.
At ISO400 there is not much discernable difference to that of the fist image. There is marginal noise appearing in the detailed areas but all are still very clear.
Although difficult to see here, there is starting to be significant noise in the detailed areas, especially the areas of gradient such as the green dinosaur, which is in shadow. There is noise starting to appear on the solid colours.
This is about the point where I would expect to start seeing significant degradation to the image and indeed there is much noise starting to appear, especially in the shadows. The sharpness of the detail such as the text is still holding fairly well though.
Even at this low web resolution I can now see significant noise in the shadows and colours. When observing this image at 100% in Aperture I can see that the solid colours are now quite noisy with dark grey pixels permeating the solid colour.
The text on the car’s visor is now very difficult to read and in comparison to the first couple of images in the series the solid colour of the wall has changed significantly. The greens are suffering with lack of definition too.
The visor on the car is now unreadable. When viewed at 100% on Aperture the image is extremely noisy. There are flecks of different colours (greens, whites, blues) appearing in the shadowed areas. These ‘flecks’ are random in appearance and do not seem to follow any pattern. The block of colour on the left (as well as the white vertical band down the middle) is now made up of noisy grey pixels which changes it’s whole appearance.
Things to note here are that, with the exception of the final image, the ISO doubles itself with each change as does the shutter speed. The final image I would have expected to be 1/160 rather than the 1/125 as I would have expected it to follow what appeared to be quite a clear pattern.
As far as my tolerance for noise is concerned, I would very rarely use the ISO12800, even when shooting at night for street photography. I find the level of noise unacceptable and would rather use a lower ISO and suffer some blurring of the image at a lower shutter speed. Fortunately, when taking night shots, the noise can often add something evocative to the image. If I am using a tripod then I try to stick with the slowest ISO I can get away for the conditions. That said, the last ISO setting is very high and actually gives a pretty good image when that is taken in to consideration.
What is slightly surprising is that my camera does not have ISO100. It was something I overlooked when choosing the camera and wish I had considered it as Singapore has a tendency to be very bright, even when overcast and ISO200 sometimes is not accommodating enough.