Originally posted by IchabodCrane One note to add -- If you shoot RAW only, there's no benefit to Highlight Protection (as well as Shadow enhancement). All it does is underexpose a RAW image by one stop (by cutting ISO in half) which you can do yourself if you think the situation warrants. If you later decide to create JPEGs on your computer, you do the same thing the camera would do to make them... increase Exposure by +1 and turn on the software's highlight protection. Should be about the same result as the camera would produce.
This is a popular notion that is repeated extensively, and depending on how it is taken can be misleading. In RAW, highlight protection does apply a very good roll-off curve; shadow correction apparently has no impact on RAW shoots.
I do a lot of RAW processing in Lightroom and Capture One (not much lately for the latter), and I can tell you that the idea of underexposing at ISO 100 (or any other setting) and then applying the proper adjustments in post is not worth the hassle, and you almost certainly won't do it as well as the camera does it automatically. Then there is the high potential for not remembering to underexpose in the first place - or not being aware that the scene needs it.
A lot of folks have read what is posted at forums for other brands and concluded that Pentax probably implements highlight restore just as poorly - when in fact it does a great job of it.
As for the K-30 (or K-01), I strongly recommend "auto" for highlight, and no correction for shadow when shooting RAW - the camera will perform at its best in these settings. My best guess is if you are mostly a JPG shooter, auto for both highlight and shadow probably works best - but I rarely shoot JPG so haven't tested it.