Your main concerns are going to be:


As you say, the ability shoot in RAW.
Relatively noise-free output (but this requirement is mitigated by the ability to heavily post-process and downsize). 
A good, sharp, distortion-free lens.


For the resolution you suggest, you should be able to get good results from a high-quality point &amp; shoot (like the Canon G12 or similar). However, you'll get even better results from a larger-sensor interchangeable-lens camera — like a DSLR. I don't think you need anything expensive — an entry-level model should do. But you should look into spending some money for a very nice lens. Maybe a 70-200mm zoom or a 100mm macro. Probably an f/4 lens will be fine, rather than a more expensive f/2.8 version — since you'll probably want to stop down for sharpness and to increase depth of field and reduce focus error. If you can use a tripod, awesome, but having image stabilization will give more flexibility.

Pretty much any brand or model of DSLR should be fine for this purpose. They all give high-quality results and have the lenses you might need for this available. 

How do I chose a good camera for texture hunting?
Where does majority of the energy for the magical effect of a potion comes from? 

Does it all comes from the brewer? Or does most of it comes from the ingredients? 

I know JKR said that you have to use magic at some part of the process of brewing (hence no muggle potion brewers) [what about a squib?]

If brewer provides all of the energy then why aren't NEWT students magically exhausted after every potion class? Hermione successfully brewed batch of Polyjuice Potion (a very potent NEWT level potion) in first semester of her second year, and while brewing it was very time-consuming and required a lot of concentration she never showed any signs of exhaustion as far as I remember.
