dSLR Camera Lens Types and Focal Lengths
You can swap lenses on your digital SLR camera. Choose from macros or zoom lenses. Experiment with specialty lenses, from Holga to tilt-shift and pinhole. Choose the right lens based on your photography style or method:
Zoom lenses have a zoom ring so you can change the focal length. They come in several types. The most common, and in many ways, versatile type is called the standard (or normal) zoom lens. You also can buy wide-angle and telephoto zoom lenses.
Prime lenses has a fixed focal length, so it can't zoom in or out. Buy the lens that matches the focal length you like best. When you compose your shots, you have to physically move closer or farther away.
Macro lenses specialize in photos of close-up objects with a reproduction ratio close to 1:1. Most macro lenses are primes.
Other specialty lenses include creative and artistic lenses like these:
LensBaby are untraditional and creative. Different types have different creative focus and depth-of-field effects.
Holga works with your dSLR and you can mount it directly.
Diana+ is similar to Holga, but can zoom much more. Using a Diana+ lens requires an adapter.
Tilt-shift: Get interesting depth-of-field and perspective effects.
Pinhole: There's no focus. The depth of field is huge. Exposure time is longer. Pinhole cameras create soft, dreamy photos.
Lenses are also categorized based on their focal lengths:
Ultra wide-angle lenses have an angle of view between 80 and 100 degrees diagonal. That equates to focal lengths of roughly 10–17mm for cropped-frame cameras and 14–26mm for full-frame cameras.
Wide-angle focal lengths are anything less than the diagonal size of your camera's sensor. Traditionally, this means anything up to around 24mm for APS-C and 35mm for full-frame cameras.
Normal focal lengths are around the same diagonal size as your camera's sensor, give or take a small range. This includes the focal lengths of 26–35mm for APS-C and 40–60mm for full-frame cameras.
Near-telephoto runs from 35 to 50mm for cropped-frame cameras. Full-frame cameras have a near-telephoto range of approximately 60–70mm. Also known as medium telephoto.
Telephoto is considered proper telephoto. It extends from the end of near-telephoto and stops before things get ridiculously expensive. Typical telephoto focal lengths are from 70–200mm for cropped-frame and 135–300mm for full-frame cameras.
Super telephoto lenses shoot incredible shots with ridiculous focal lengths. They're all primes lenses, so you can't zoom in or out.