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Old 29-01-2008, 07:11 AM
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iceman (Mike)
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iceman is offline
Join Date: Sep 2004
Location: Gosford, NSW, Australia
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Hi Steve
Originally Posted by skwinty View Post
2. if you shoot using raw you should be using iso 400 only as there is no advantage using high iso when shooting raw.
There is no correlation between shooting RAW and the ISO. The ISO controls the amplification of the data, and so shooting with a high ISO means you need a shorter exposure time for a given object. Whether you use RAW or not, the effect is the same.

Higher ISO brings more noise into your image too - so it's a trade off between using shorter exposures with more noise, or longer exposures with less noise.

For astronomical applications, this needs to be considered depending on the brightness of the object, the tracking/guiding capabilities of your scope/mount, your local light pollution, how many frames you're going to take (for stacking - to reduce noise), etc.

Shooting RAW is best because it lets you control the white balance in post-production, and it gives you the full depth of the data to work with, rather than an 8-bit jpeg which is already compressed and has less dynamic range.

btw Dennis, excellent presentation of the usage of live view. I tried it with a friends 40D a few weeks ago, but we couldn't get it working through his Mac laptop at the time (it was his first try at it and we had the wrong settings).

The 40D sure is a fine camera.
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