Originally posted by kerrowdown I wouldn't think so, but hey, I stopped using PEF many moons ago in favour of DNGs.
He's one for you and don't ask me to explain, when importing into LR4 catalog/library, I've noticed that LR4 DNGs can be half the file size of Pentax straight from the camera DNGs.
Sorry, don't know why the DNG files would be so different in size.
As for my original query, after looking at the respective histograms, I'm now thinking that it's not so much a difference between raw and jpeg, as it is the propensity of Pentax to be conservative in exposure in order to not blow out highlights, whereas the Canon images are typically exposed more to the right. The Pentax images are sometimes too conservative.
Not a big deal; easily correctible.