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Old 13-03-2008, 11:59 PM
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Stargazer292
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RAW files

Hi everybody,
Can someone please explain the advantage of using RAw images and how to use them for astroimaging. Thankz
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Old 14-03-2008, 06:12 AM
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madwayne (Wayne)
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Hi Andrew,

I think you will find what you are looking for, and more, in this post.

http://www.iceinspace.com.au/forum/s...ad.php?t=29699

It's an interesting read, in my opinion, and very well written.

Clear skies.
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Old 14-03-2008, 08:36 AM
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Quote:
Originally Posted by madwayne View Post
Hi Andrew,

I think you will find what you are looking for, and more, in this post.

http://www.iceinspace.com.au/forum/s...ad.php?t=29699

It's an interesting read, in my opinion, and very well written.

Clear skies.
This is a very good paper, indeed.
However, for a beginner, it might be a bit too much of technical details...
So, in a nutshell, RAW format is better simply because it contains ALL the data collected by camera during exposure.
JPG (or some other formats) file does not because:
- the resolution depth is 8-bits per colour channel (original data could be up to 14 bits per ch, 400D has 12 bits.. still MUCH better than 8)
- lots of information is also lost due to the compression (compression algorithm is substituting real information with similar standard patterns, reducing the size of the file this way by storing just a list of those patterns and not the patterns themselves). Obviously, the jpg image will look similar to the original, but if you have a closer look by zooming into high contrast details, you would be able to see the artifacts of compression, which may be very visible if compression is high. So you will actually see what was not really there...
- Subsequent saving of the jpg image (after some editing for example) will deteriorate the quality of the image to the point of destroying it. RAW file remains intact in that respect (except for the changes done, of course).
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Old 14-03-2008, 06:52 PM
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Yep, what you have just said has nailed it pretty well, raw capture is the way to go, and from there on you can work with the data collected.

Leon
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