Continuous Fire Mode - Works like a motor drive; just hold down the shutter release button.
There is minimum to no waiting between shots. Look for a camera that takes
something like 3 Frames per Second, has a large temporary storage buffer
to hold 6 to 10 frames while it writes from the buffer to the memory card,
and allows you to continue shooting as fast as the buffer empties. Most
point and shoot cameras can only handle one image at a time and are locked-up
while saving the current snap.
Controls - Look for a camera with an additional grip and duplicate controls for
portrait orientation. It puts the shutter release and control wheels back
where they belong so you can easily switch orientation on the fly.
Other Advanced features:
Memory Cards - Select a camera that uses easily changable memory cards such as Compact Flash Cards up to at least 2 Gb. When the memory gets full you want to be able to swap cards in the field to continue shooting without delays. Depending on file size and type, up to 200 RAW format images per card.
Digital Darkroom - The best cameras can produce a true digital negative so to speak. When images are shot in the RAW Format, the camera only records what each photoreceptor site actually sees (12 bit), and the camera settings. This reduces the file size, and allows you to "develop" later. Except for the lens settings like Focus, Zoom, and F-Stop, most camera settings can be changed AFTER you take the shot! Make sure the camera comes with software plug-ins for photoshop that allow you import the cameras native RAW format into photoshop, and to adjust the exposure, sharpness, tone, color space, white balance, etc., to get many different results. If the camera only supports JPEGs like many point and shoot cameras, you have already lost a lot of color information because JPEGs are compressed. When you shoot in RAW format and post process the images you want to keep, your images greatly exceed the quality expected. Once the RAW image is in photoshop, you can save in any format you want, but the best quality modes are 24-bit BMP and 24 or 48-bit TIF. Some programs other than photoshop have trouble opening a 48-bit TIF, so 24-bit TIF (8-bits/channel) is the usual standard for printed publications.
Battery Life - Check out the battery life, battery type, and charger options before making a purchase. You don't want a camera that eats batteries like candy. The rechargable lithium-ion types work well. You may want to be able to leave it turned on all day, always ready. You should get at least 500 to 750 images per charge when used with a $20 card reader to transfer images to your computer. Expect less if you transfer with the USB cable. For studio work, or if you just have to use the USB port to transfer images, make sure there is an optional AC adaptor. Always carry a couple of spare batteries charged and ready to go.
Optional Accessories - Many cameras list optional accessories in the manual or on the box, but when you go to try to buy them they can't be found, were never available, or are no longer available. This might be particularly true if the camera is an older model, and dealers are looking to close out stock to make room for the newer cameras. Check out the true availability of adaptors, cables, speedlights, lenses, battery packs, software, and other optional add-ons before making a purchase. It is best to obtain the accessories you will need at the same time you purchase your camera.