loading RAW files vs TIFF files into DSS?

[lookus]

hi,

i take images using a 450d. i save the files onto my laptop as RAW files. should i load these RAW files into DSS and save the final as a 16bit TIFF for processing or should i first convert the RAW files into 16bit TIFF files and then stack these into DSS?

i have heard conflicting opinions here. i would have thought that RAWs into DSS would be better . if it is what settings should i use in the RAW tab in DSS?

thanks for looking.

[Octane]

Use RAWs and let DSS convert them to TIFF for you for greatest processing flexibility.

Converting to TIFF from RAW would make DSS work very, very hard as the uncompressed TIFFs will be enormous.

H

[luigi]

It depends. Sometimes I like to do WB, optical corrections, distortion CAs, etc before stacking so I go RAW->Tiff->DSS. Other times I just use the RAWs in DSS. For landscapes with stars I always convert to Tiffs first. For astrophotos I tend to use RAWs more than Tiffs.

I'm also interested in the reasons why some people only use one approach or the other.

[mswhin63]

I agree with the above. so many times i have wanted to make simple changes to an image before sending it to DSS (mostly widefield) although i tend to use TIFF more than RAW. I think experience is my main limitation.

[Octane]

The thing is, with all the pre-processing we do on our images, I feel it is rather unecessary to have to change white balance, etc., first, because we can make all relevant changes in post processing. And, this is coming from a a purist -- you can read my rants against using Lightroom/ACR over Digital Photo Professional elsewhere on this site.

Having said that, when dealing with Canon RAW files, if you really wish to, you can make your edits to a RAW file, and then re-save it as a new RAW file, then, send that through to your pre-processing software; in this case, DeepSkyStacker.

I often do this with my landscapes where I need to blend certain components from the single RAW file.

H

[luigi]

Mmmm I think that if you edit a RAW and then feed that to DSS the changes are invisible to DSS. All the edits you do are meta-data in the RAW file. DSS only takes the luminance value of each pixel and proceeds to do demosaicing using the selected method.

[Tandum]

Why would you use DSS for daylight landscape images. DSS = Deep Sky Stacker?

DSS likes raw files in but you have to save it out as a 16bit tiff. It's autosave file is a 32bit tiff and photoshop don't like 32bit files :(

[luigi]

AFAIK DSS won't stack unless it can detect stars, even if you select no-align method it needs to detect stars. This is a nonsense to me but so be it. DSS can be used for any landscape as long as it detect stars.



Photoshop can read a 32 bit file as long as you save it as floating point 32 bit tiff files. Photoshop doesn't like integer 32 bit tiffs.
;)

[Tandum]

IMHO a landscape does not have stars it has landscape else it's a wide field shot.

And if you want to get pedantic, PS can read a 32bit float but can not manipulate it. 95% of the adjustment tools are greyed out in CS3.

The guy is trying to stack canon shots of the sky, why do people always try and make it hard.

[luigi]

Maybe you never saw a landscape taken at night ?



I'm using CS5 sorry about that.
Another option is to save the file as 32 bits FITS file and use Fits liberator to read the file into Photoshop.

[Octane]

I just realised he could also just use Photoshop's built-in align and stack features.

Convert RAWs to TIFFs using Digital Photo Professional, then do the above in Photoshop.

H

[lookus]

thanks for all the responses.
from what i have been able to glean from the comments there does not seem to be any great benefit in terms of final image quality by first converting the RAW to a TIFF prior to stacking.

right?