Originally posted by beebs it took me from 10:30 am until about 5 pm yesterday to get the two shots I was thinking were "ok"...not GREAT, but "ok".
That's the famous PS learning curve you might have heard about. Without seeing the art live, I can't comment on colour temperature, and I don't know how much you want the texture of the different media (canvas, paper, oil vs. acrylic, etc.) to be visible. You aren't doing restoration, so feel free to use your computer to tweak the image to give it a look that you like. Use software to correct lens distortion, adjust colours and exposure and so on. I don't see anything in the two images that can't be enhanced with software. By all means put your M 50mm on your K-30, take a few shots with slightly different focus to get exactly what you want in focus, and don't lose sleep over getting exactly the right exposure. Once you figure out how to tweak one image to your satisfaction, the rest will be much, much faster. And for uploading to the Internet, use JPEG files. With reasonably high quality settings (80+) you will retain all the detail a computer monitor can give you. I don't know the details of how bitmaps are embedded in PNG files, but file size is seldom related to the sharpness of the image when displayed on your computer.
With some software fine tuning, those 16 MP RAW files from your camera will be suitable for any size of print. I'm pretty sure your beloved didn't create with a magnifying glass. If I can detect different thickness of paint in the pictures you posted, you are capturing all of the detail you need. You probably know better than I do that exact copies of true art are missing something.