Well I don't normally like directing to other forums so I copied and pasted a post I made elswhere a while ago....
SO YOU WANT A DIGITAL CAMERA
Digital Vs. Film
Just like when choosing between glass tanks or acrylic tanks there are advantages to each, and those who swear by one or the other. For me I see advantages in each. As the internet is a digital media I will point out some advantages of digital.
Top Reasons for Digital Cameras
1. Instant Gratification. Good things come to those who wait, but sometimes you don't want to. Shoot, pick and print; or shoot, pick and upload. Whichever way you go you can be showing your shots in a few moments.
2. Take Two. Combined with the joy's of instant gratification comes the ability to reshoot immediately as needed. Hey we all need second chances, sometimes thirds and fourths even. Fish, just like two month olds don't hold still. Rather than waiting for prints you'll know right away.
3. Shoot to your hearts content. Some of us are passionate about our tanks, some are passionate about getting the moment. For those of us that are both a large enough media card will allow you to shoot for much longer than the average roll of film.
4. Keep what you need. As it's digital there's less waste and you only need to print out what you need. That might be one shot out of 200+ that fit on the card or it could be all of them. From a recent shoot I accepted 13 out of 115, and only liked 4 of the 115.
Things to Look For in Purchasing Digital
In no particular order here are some things to pay attention to when purchasing a digital camera.
Shutter Speed. Some of the fish we keep love to play a non stop game of tag, just because they are fast doesn't mean they shouldn't get a chance to get their picture taken. Even if they aren't the ones you plan to shoot there may come a time when you feel a need to shoot them i.e. illnesses and such. The ability to get a shutter speed of 1/30 will help to capture a zippy zebra danio.
Macro Focus. Or the ability for the camera to focus on close objects. This is often signified by a picture of a tulip somewhere on the camera. The best lighting and the best tank in the world will mean nothing if you have to shoot your cute little ottos from across the room. Many cameras come with macro focus, it may be a series of menus that need to be selected, or just one button.
Fast Lens. Basically the ability of the camera lens to open wide enough to allow for a fast shot in low light. This is given by an aperture of a small number, and in this case the smaller the better. An f-stop or aperture setting of 2.0 in macro mode is a good starting point.
Tripod Mount. Believe it or not, some cameras don't come with this basic feature. If the camera doesn't have a tripod mount and you have pictures that are blurry due to camera shake, you can always prop yourself against a chair or set the camera on a stack of books. Holding perfectly still is always a must, even if you have to hold your breath.
Film Speed. The cameras you look at should have some choices in varied film speed. This is a number taken from conventional film sensitivities that allows how much light the camera needs to shoot a good picture. These numbers can range from 50-800. Especially if your tank has little lighting go for a camera that has speeds of at least 400 ISO for shooting in low lit conditions such as a tank.
Mega Pixels. Every ones favorite, here is one case where bigger doesn't always mean the best. Depending on your publication medium you may be able to get a better deal on a camera by purchasing one that has less Mega Pixels. If you are thinking of displaying your pictures mostly on the web a lower mega pixel may work fine. If however you are considering entering in a photo competition you may want to go for the higher number.
700 is never enough...a few more words, just for fun.
At the time of this writing we're entering the eve of the holiday shopping season...there are likely to be some great deals on some great cameras out there, but before making a purchase be sure that you've done your research. I'm open to a PM @any time. I can't tell you straight out which camera out there is the best but if you've found a few that look good to you I can give my own opinion on them.
If your looking for a great site that does reviews on digital cameras I highly recomend http://www.dpreview.com over consumer reports. For the past few years I've been following their reviews and found little to no bias in their work, as well as comparison test shots for everything from noise and white balance to pincushion distortion and lens shading . Most all cameras that they have reviewed include a picture gallery and unlike some other sites they know cameras.