It doesn't help that I cannot recall ever seeing it done well. Honestly, based on most of the covers we show here, I haven't even seen it done in a way that wasn't irritatingly distracting - all the overly "broken down doll" modeling poses which are wildly out of place - all the pneumatic, plastic models - all the anachronistic costuming choices and so on ...
Most of the cover photography I see (and, again, this thread exemplifies this) seems NOT to be done for a specific novel. It's some pretty model, a period or vaguely period dress, several rolls of film, and sell it all to a stock image company. Too many images seem chosen out of a catalogue, not designed specifically for one work. As we can see, it all becomes plug-and-play - and, after a while, it all looks seen-this-before.[/quote]
I don't disagree with any of that but frankly, I don't think this thread is the best example of good cover design. Most of the books posted here are indie books using stock photography and I agree, it doesn't look great. But I do think there are plenty of good historical covers using photography and this is why I say when it's done well, whether it's a photograph or painting, it works.
Here's two just off the top of my head which use photography and I think work very well:
