Mixing two exposures...

Hey all,
I have two exposures of the same image. One i exposed for the subject and the sky was blown out so i exposed one for the sky too. The only thing is i heard that this has to be shot in RAW for them to be able to be mixed. Is this true? If not how would i go about using the good sky with the good subject? Thanks

No they don't have to be RAW but they should both be the same format and preferably they should have been shot from a tripod so that everything lines up. I will sometimes put a different sky in a shot. In this case I create a selection of everything that I want replaced and will delete this. I will put the sky shot below this one it shines through. I keep a library of a couple hundred different sky and background images to use for this very thing. The key here is make sure that your selections are good. If you have alot of trees in the shadows or midtones and you don't do your selection right you may end up with up very noticeable blend (or lack thereof).

I did a quick google on "blending images in photoshop" and got alot of results. Went through the first couple and they look decent.

does not have to be shot in RAW. i always shoot mine on a tripod or, if a that isnt handy, before i shoot i set to burst mode and shoot consecutive shots while holding as steady as I can. but to properly pull it off you need it to line up as best as possible.

here's a couple i did recently...