Just purchased a Pentax 1st DS and my Photoshop CS does not seem to want to process my RAW files. Checked the upgrade list but could not locate one for CS that would allow processing. Yes, if I upgrade to CS2 there is an upgrade to handle them. Are there any options for CS?
Adobe isn't upgrading ACR for CS. Your choices would be to upgrade to CS2, use Elements 4.0, or one of the other RAW converters like RawShooter Essentials.
I downloaded the Camera RAW 2.4 update for Photoshop CS dated 1/31/2005, 1.7MB from the Adobe website and I have no problem converting RAW images from a Nikon D70 and a Pentax *ist DS! If this update doesn't work for you, I would email Adobe; they have been very responsive to some questions I had in the past. Good luck!