Yes, Samsung used its own firmware, which does have a different JPEG engine and doesn't support Pentax's proprietary RAW image format. Also, Samsung lost interest in their Pentax-based cameras and ended support well before Pentax did the same for their equivalent models, so even though Samsung based its firmware updates on the Pentax equivalents, they called it quits and left some shortcomings uncorrected, despite Pentax having fixed them in later updates. For instance, my GX-20 will not write to 32GB cards even though the Pentax K20D can be updated to correct the problem. Unfortunately, the Samsung cameras will not accept the equivalent Pentax firmware updates. Updates and PDF copies of manuals are also harder to find as Samsung doesn't even acknowledge the GX series cameras' existence on its Website. Fortunately, they are archived on third party sites. Had I known then what I know now, I might well have thought twice about buying my GX-20, but I can live with its shortcomings for the price I paid.
Originally posted by ChristianRock I remember reading that while the Samsung GX cameras had identical hardware to the Pentax equivalents (and were made by Pentax), Samsung used their own JPEG engine. So if you shoot JPEG I would look for a Pentax model. *istDLs can be found for 60 dollars on Ebay.
If I get one of the 6MP cameras it will be an *istD for the better viewfinder. I've considered one for a while, to give to my older son who currently uses my RZ18 - he's 8 years old so I'm waiting for him to grow a bit more before handing him a DSLR. But maybe I could get it sooner and test drive it for a year or two...