I just recently purchased a Pentax K-r. It has two formats to shoot raw with, PEF and DNG. Are there advantages or disadvantages with using one over the other?
PEF is Pentax's proprietary RAW format. DNG is the semi-standard owned by and promoted by Adobe.
In reality, there's no practical difference. They both hold the same information. It seems like there might be an advantage in having a standard format, but as a practical matter, RAW converter software needs to be updated with information for each camera anyway, and so DNG doesn't really add much. And pretty much all software that supports Pentax cameras via DNG can also read PEF files.
In older Pentax models, PEF could be (losslessly) compressed and DNG was always uncompressed. In modern cameras, they're both compressed.
When I went on a 10 day travel trip with my K10D, I was using two 16gb sd cards. I went with PEF vs DNG because it made a significant difference in the number of shots I could get on the cards. I could fill up a card each day (plus some) and had I gone with DNG I would have not been able to carry as many pictures on the card. This was a BIG factor in my inertia with staying with PEF.
Now that more modern cameras compress the DNG it's not as much of a big deal.
However, I see that Lightroom will create DNG files no matter what the raw file is anyhow, so I'm about to switch back to DNG to save the step.
I use Pentax camera a lot and I prefer Adobe DNG, because it works very well in Adobe's Lightroom. I know that full support for PEF is also there, but in my case is more habit then the choice based on some in-depth comparison of the formats.
If you look at the internet forums people seem to have various opinions on that topic. Some prefer more generic Adobe DNG others native Pentax PEF.
Here is a handful of links you may find interesting: