Having problems getting my head around RAW / TIFFs files

[Tom OD]

Hi Group,

While I have been imaging for a number of years, I've been using my 7D recently for landscape / nightscape shots. I normally do deep sky photography, and work in TIFF format after saving it from the original calibrated FIT file.

With 16 bitt TIFF, i'll have a nice dark un touched file in linear form to stretch etc... 

When I open a RAW file in PS, or PI I get an already stretched image albeit not too much. Its not as stretched as the jpeg. I set the shooting mode to jpeg +RAW for each shot.

So is the only difference between jpeg and RAW, that the camera performs its own internal s/w stretches from a RAW file to o/p the jpeg? I was under the impression that a RAW file should be un processed completely, and be in linear format. When I open it, it's Non Linear.

I cannot remember what happens if I save the RAW as a TIFF and then open that. 

Is this something to do with a DSLR being 12bits, and my CCD being 16 bitts, or is a RAW format just non linear and not as good as a FIT /TIFF format from a CCD?

Thanks Tom.

[JG777]

Depends on how you set your camera up. My Nikon's have picture control settings which can be applied to the raw file and just reset in the camera or in PP. So you should be able to set your raw files to drop out of the camera *clean* . One thing to remember though you can only view raw files truly in a raw editor, so if your not in the editor you are only actually viewing the embedded jpeg.

[Mr Spock]

The RAW file contains all the basic image data. Anything else is just processing that data, such as picture controls etc. Jpg files and TIFF files are created from the RAW file.

You'll find it's the software changing the RAW file.

[Psychobilly]

You can select and modify the "curve" thats applied during he "raw" development process... 

In Adobe Camera Raw

  or DPP 

Peter...

[dph1nm]

You will find the various camera settings which control the jpeg view are embedded in the RAW file header. So most photographic software will read these and try to implement them when displaying the image.  It is actually quite difficult to get anything to display true RAW. I think if you use Canon's DPP and click on the little box marked linear in the RAW settings dialogue then you will get something close. But it still has to decide how to fit 12/14bits onto your monitor's display!

NigelM