The Nikon D80 camera is a crop sensor digital Single Lens Reflex camera. The term "crop sensor" refers to the size of the sensor in relation to full frame lenses. Crop sensor cameras crop part of the image from lenses made for full frame cameras, such as Nikon's DX series of lenses.
Compatibility
You can use all Nikon DX series with the Nikon D80. Nikon design its DX lenses to fit on all of its DSLRs, including APS-C sized sensor cameras, such as the Nikon D80. APS-C, or Advanced Photo System type-C, refers to the size of the sensor. A Nikon APS-C sized sensor is 15 mm high by 22.5 mm wide.
Crop Factor
Nikon makes its DX series lenses specifically for the DX series of cameras, including the D80. The lenses have a 1.5x "field of view" crop. This means that to determine the actual focal length of the lens when using it on a D80, you must multiply the effective focal length of the lens by 1.5. This calculation reflects the smaller coverage of an APS-C sensor, compared to a full frame sensor. For example, if a DX lens is set to 50 mm on a D80, it will have the same field of view as a 75 mm full frame lens on a full frame camera.
Advantage
The advantage of the 1.5 crop factor on DX lenses is that it is more cost effective to gain, in effect, a longer, or more zoomed-in, lens. For example, telephoto lenses for shooting subjects, such as wildlife and sports, have long focal lengths, such as 200mm. In order to get the same field of view on from a DX lens on a D-80, you must use a lens with a focal length of 133 mm. In general, shorter telephoto lenses cost less than longer telephoto lenses, so you may be able to save money by using a DX telephoto lens on a D80 body.
Disadvantage
The disadvantage of using DX lenses on a D80 camera is that in order to get a wider view, or the ability to see more in your lens without stepping backwards, you must use wider lenses than you would with a full frame camera and lens. For example, if you wanted to achieve a field of view equivalent to a 25 mm full frame lens, which is a wide angle suited to photographing groups of people in a room, you would need to use a lens that has a full frame equivalent focal length of 16mm. These super wide lenses are typically expensive to manufacture and, therefore, will cost you more.
Tags: full frame, field view, focal length, telephoto lenses, APS-C sized, APS-C sized sensor