Wednesday, August 24, 2005

Color, Noise and ISO 1600


One of the reasons I choose the Canon XT over other camera manufacturers was because of the lower noise levels at higher ISO numbers. Reviews even said the noise levels were similar but with a different look to the more expensive Canon models.

After my return ferry ride from Sunday's Wards Island trip I decided to take a few early evening shots with my 100mm f2.0 lens. To save the setup of the tripod and also because I had only used it a few times I set the ISO level to the maximum of 1600. In the picture above I was expecdting bright saturated colors but instead they were dull and slightly dirty in a way that could not be corrected with picture window pro (the software I normally use) so much so that I will have to go back and shoot it again with my tripod.

This is a 4x zoom of 4 parts of the top photo: notice the blotchiness of the colors not only in color intensity but in the actual color value. I can attribute some of it to using jpeginstead of raw but I doubt that does much more then smooth out noise spikes. I find the noise more annoying then the graininess of film. Film has most of the noise is uniformly distributed spatially with the noise being primary intensity rather then in color value. Increasing ISO number does not for the most part increase the sensitivity of image sensor it is really only increasing the amplification. Electronic noise causing a lower signal to noise ratio is still the biggest hurdle preventing image sensors from reaching the dynamic range of film. More about color in a future post.

Another Trolly Stop photo







Because color is not so important to the subject matter in this photo I think ISO 1600 is not too bad here.
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