I use a Cannon SL1 with the stock 18-55 lens that came with it. You can't get as close as a true macro lens, but you can still get some amazing shots. The best piece of advice I received about getting good shots was to set a custom white balance using a White Balance Lens Cap. I picked one up for $10.00 at a local camera shop. Take a picture of your tank with the White Balance lens cap on. Then use that picture to set a custom white balance. Once you do that remove your lens cap and start snapping your shots. Your camera should adjust for the blue after that and still give you the pop your eyes see when looking at the tank.
Took these pics yesterday with a cheap top down porthole in jpg and posted straight to the internet.
Some are a little over exposed, but most of them came out pretty good.
This one looks like it's been touched up, but I guarantee it hasn't.
Here is another really nice one
Check out the rest of the photo's at http://www.facebook.com/TikiCorals/photos_stream
