Old 22-06-2009, 02:57 PM
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toryglen-boy (Duncan)
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Working with CR2 files

ok, so i have been using JPEG's, and soon i am thinking of moving up tp CR2's so i can extract more info from them.

Is there anything i need to know when working with them? i use Paint Shop Pro 9, and Photoshop CS4 Extended. Can CR2's be stacked in DSS? are they treated teh same way as JPEG's?

many thanks for reading my inane drivel

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Old 22-06-2009, 04:19 PM
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Bassnut (Fred)
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You probably know this, but CR2 files are about as opposite to JPEGS as you can get. PS can load CR2 files, but that never happens, because calibration/aligning and stacking is done in an astro app well before PS, so you would never load an astro CR2 into PS directly.

Theoretically, stacking alone doesnt care what the file format is in, it works the same, but you wouldnt normally would be stacking CR2, it gets converted to TIFF or FITS before that. (I dont know if any astro apps stack CR2s anyway.).

I dont know about DSS, but IP decodes CR2 and converts to tiff or fits before stacking, so they are the formats used to export to PS.

Its not essentiall that the astro app reads CR2 really, you can use the Canon prog that comes with the cam to convert to tiff first, no loss in data, tiff is 16bit, non-compressing.

Just forget JPEG altogether if you move to CR2 raws.
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Old 22-06-2009, 04:57 PM
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tlgerdes (Trevor)
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Hi Duncan,

DSS will read CR2 files directly. Best thing as CR2 files are 3 times the size of JPGs for your 1000d, is to download them direct to your computer after taking them with EOS Uitility, dont store them on the camera.

Remember you will have to redo darks and flats as DSS doesnt like it when you have different formats for each component.

Also save out of DSS as 32bit rational tiff then convert down in photoshop to 16bit, dont save in DSS 16bit, it does a 5h1t job.

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Old 22-06-2009, 09:58 PM
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dugnsuz (Doug)
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Always convert CR2 (RAW) files to TIFF files using the Canon software (Digital Photo Professional) - then you can stack in your program of choice and manipulate in PS.
I think I'm just repeating the above though!!!
Some say start off in JPEG before moving to RAW file processing (particularly when learning), probably because the CR2 files are much larger and take a bit more computer grunt to manipulate - especially in large numbers...Like Wot We Astrophotographers Do!!!

You can "trial and error" ideas out more easily with the smaller JPEGs than you can with RAW files. When you have things sussed - RAW files will give you the maximum quality from your DSLR.

Good luck
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Old 23-06-2009, 07:44 AM
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tempestwizz (Brian)
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Hi Duncan,

My 2-bob's worth.....I always shoot in RAW (.CR2). I accumulate my shots onto one of several CompactFlash cards, which I change out regulary through the night.

I view the RAW files in the Canon program that came with my 20Da - I presume the 1000d came with something similar.
In that program, I check, and adjust the camera if necessary, to get an exposure where the histogram is well away from the left-hand egde of the graph, but not too close to the right-hand side.
I then adjust the view to 200% to check for tracking, polar alignment and focus issues. If the stars look good at 200% you're doing the right thing.

From there, I move onto IRIS - which is free.


Although there is a steep learning curve involved, it is well worth the effort of perseverance. There is a yahoo group dedicated to Iris, and a couple of excellecn tutorials included to help you work through the process.
Iris converts the .CR2 format into its own .PIC format. It carries out all the required functions - darks, flats, alignment, stacking and stretching beforeyou end up with a .PSD format which you can finish off in Photoshop. Saving to .TIFF or .JPG only at the end.

There is a learning curve for sure, but with practice, you will improve. The stars will be out there for a few years yet, so no need for haste. Think of it as character building!


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Old 23-06-2009, 03:36 PM
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Octane (Humayun)
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If I'm not mistaken, DSS does pretty much what IRIS does, but with more of a GUI-driven process.

For what it's worth, I have used IRIS since day dot, and it is just incredible what the software can do.

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