Re: What would be a great DSLR for fish/aquarium photography
Hey sanj,
Among the short list of SLR cameras you mentioned, it won't really matter which you buy. You won't be able to tell the difference in your photos, even if you bought all of them and took a picture of the same subject. Brand freaks love to argue the case, but none of these cameras can distinguish themselves to be considered significantly superior. It's the photographer that distinguishes himself/herself. Lenses are about the same as well when direct comparisons are made. Only a few very special lenses distinguish themselves and they are all flawed in some way. So the trick of getting the best out of a particular brand or model is for the photographer to understand the basic weaknesses and strengths of a camera/lens (which they all have). Then, avoid the weaknesses. Since you have to do this no matter which you get, it doesn't matter which you get. The idea is to just start taking pictures and to learn the machine.
When people see a great photo the first thing they want to know is what camera or lens it was taken with. Ironically, it' s probably the least important stat. It's what the guy/gal was seeing that was most important, and it's what his/her technique of playing to the camera's/lens' strength that is important.
The real differences in those cameras you listed are more about what features they have, where the buttons are placed relative to the fingers, how easy it is to access the menu items, and so forth. The photographic performances are pretty much the same, and if one camera is more accurate than the others, then it's more likely to more accurately reflect your lack of technical or artistic competence in the photo than it is to make a better picture.
So instead of being confused an tentative, I'd think about things like; what brands do my other gear-head friends have, maybe I could borrow some of their lenses if I buy the same brand. Think about pricing and best deals if money is an issue - speaking of which, you don't have to buy the latest model, or even brand new unless you're worried about warranty. A DSLR500 will not necessarily take better pictures than a 5D classic. A D3000 is not automatically better than a D40. Camera companies just try this on to keep you buying more gear by adding more useless features like HD Video. I wish they would concentrate on making real improvements like longer lasting batteries, for example.
I agree with Tom that it would be better to have good ISO performance, because lenses with wide aperture cost a lot more, and wide apertures don't give the best depth of field, so you'll have very shallow focused areas if you shoot wide open. Lenses are typically at their worst performance in terms of sharpness and distortion when used at their widest apertures anyway. You can also buy a flash and a flexible flash cord (or remote control) so you don't always need exotic studio lights, but that's something you can look into later as your skill increases. Remote control flash feature might be something to pay more attention to even if the camera comes with a built-in flash.
The lenses that come with the kits are for general photography so you might want to consider more specialist lenses like a 100mm macro if you can afford them or consider a great "do-it-all" lens like the Nikon 18-200mm f/3.5-5.6G, again, a bit pricey but you won't need another lens because it covers the entire range. There are Canon and third party equivalents (Tamron, Sigma, Tokina and so forth).
Cheers,