Originally posted by rawr Plus, if you shoot RAW exclusively, those settings won't do anything for you anyhow.
Sadly, some folks still don't understand the reality of the situation. In RAW, when highlight compensation is activated, the system is directed to underexpose by one stop and institute a very natural highlight roll-off to prevent blown highlights. This comes at a minor penalty to shadow noise. When Auto HC is instituted on the K-3, you will never see it instituted unless considerable clipping occurs (not minor specular clipping), As such, assuming that you use a proper quality converter that picks up the marker (LR, C1, DxO, the OEM, and several others), you will safeguard at least somewhat against blow-outs in high contrast scenes - and get an added roughly .8 EV dynamic range improvement in the process. Frankly, I wish Auto HC was a bit more aggressive such as how it was implemented on the K-30, K-01 and others, but Pentax decided to err in the expose to the right side of things - on a sensor that does not really need it.
Only Shadow Compensation has no effect on the RAW images. This always has been the case with Pentax, so the whole mythology behind the incorrect notions started so many years ago really needs to be dispelled.