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ISO Settings Effects On Dig Photo

Thu Feb 27, 2003 1:13 pm


I have been involved in photography to one degree or another for over twenty five years and understand that the higher ISO film you have the higher grain levels you have thus lower quality.

What effect does higher ISO settings have on overall quality of digital photography. I am presently shooting my S602 on ISO160 and have been considering jumping it up to 400 so I can use a little faster shutter speed and get a little more DOF.

I want to get quality that I can get some nice 16x20 I am shooting in 6mp fine mode.

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RE: ISO Settings Effects On Dig Photo

Thu Feb 27, 2003 2:25 pm


The higher the ISO, the bigger the dots. Anything over 800 and when you hit so USM you get more grain then David Hasselhoff.
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RE: ISO Settings Effects On Dig Photo

Thu Feb 27, 2003 6:26 pm

Noise, not grain - there are important differences. One of these is the fact that unlike grain, noise varies according to the colour channel. Usually the blue channel is the noisiest so one trick is to exclude this channel when sharpening. There are also a number of noise reduction plugins for Photoshop which use complex masking, blurring & sharpening processes (see for example).

And there is the standalone app Neatimage which does a surprisingly good job - there is a free demo if you want to try.

Note that none of this applies to film grain - not quite sure why, but I suspect its to do with the fact that noise can be more readily isolated because the effect varies across the different colour channels and to some extent can be distinguished from genuine image data. Grain, on the other hand, once scanned is an integral part of the picture occuring in all channels equally. Having said that note that Neatimage can be used to reduce scanner noise often found in the shadow areas of scanned slides and prints.

Clever though this technology is, I don't think it matches shooting at a low ISO - which is my preferred approach. But noise reduction filters should be in any digital photographers toolkit for those times when high ISOs are unavoidable.



Colin K. Work, Pixstel

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