The Pentax K100D seems really nice but I am curious about the battery time.
How is it compared to its competitors when it comes to battery time.
I have not found any information regarding that.
There is nothing wrong with wanting to know about battery time, but don't let it be a deciding factor in which camera you end up with.Battery timeis not so critical unless you only have one battery. Just buy another battery or two. You will probably end up doing that anyway. If the reason you are curious isto factor how many batteries you need, then that is an entirely different story. You probably won't be able to go by that unless someone includes that finding through actual use in a review or someone who owns the camera. If the manufacturer publishes the information in a spec or feature summary, you can rest assured that they will post maximum life under ideal conditions. Most of these new cameras are actually pretty good and there are some settings that can be user programmed to maximize on battery life. Most cameras turn off automatically or at least go into a standby mode. I left mine for days by accident and as soon I touched a button it woke up. Leaving it in standby sometimes is quite useful, because sometimes a cameras start-up time can make you miss a shot.
As for advice on batteries to buy, I would avoid the real cheap off-brands that you find on EBay. Some of those things are pure garbage. Some shooters insist on OEM batteries, but they can be expensive depending on where you buy them.I have purchased aftermarket batteries from reputable manufacturers like Maxell and have had no problems.