- The amount of megapixels your camera has relates to the size of the print you can make without having to worry about photo quality--the more megapixels you have, the larger high-quality print you can make. The SD 850 and SD 870 have 8 megapixels, which is more than enough to print 8-by-10-inch or larger prints, according to Target's 2008 how-to guide on buying digital cameras, which recommends using a camera with at least 6 megapixels for prints that size.
- Optical zoom in a digital camera means the camera has a lens that physically zooms in and out on your subject, bringing it closer to you. The more optical zoom your camera has, the closer you are able to get. The SD 870 has 3.8x optical zoom, which is slightly higher than the 3x optical zoom that most compact cameras have. The SD 850 has just slightly more optical zoom than that--4x.
- One of the main benefits of a LCD screen on a digital camera is the instant gratification it offers by allowing you to view your pictures immediately after you take. In addition to this feature, the LCD also allows you to compose and shoot your photos without a viewfinder and set and review your camera settings. The SD 850 has a 2-inch, 230,000 pixel LCD, whereas the SD 870 has a 3-inch, 230,000 pixel screen.
- The SD 850 and SD 870 come equipped with a rechargeable Lithium-ion battery pack--the NB-5L. The NB-5L can take up to 230 photos between charges on the SD 850. The SD 870 is a little more energy-efficient, allowing you to take up to 270 photos per charge.
- For some people, the color of their camera is virtually as important as its features. For those people, the SD 850 and SD 870 might not be the best choice. The SD 870 is available in silver and black, and the SD 850 is available in only silver.
- The SD 850 is 3.56 inches wide, 2.22 inches high, 1.04 inches deep and weighs 5.82 ounces. The SD 870 is 3.65 inches wide, 2.32 inches high, 1.02 inches deep and weighs 5.5 ounces.
- As of September 2009, Canon has suggested retail prices of $249.99 and $279.99 on its website for the SD 850 and SD 870, respectively. Canon notes, however, that that is only a suggested price and that the retailer you buy your camera from determines the final selling price.
