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Canon Super Telephoto lens
400mm f/5.6
Sigma 55-200mm f/4-5.6 DC Telephoto Zoom Lens
for Canon Digital SLR Cameras
Gail's DSLR dilemma Blog
DSLR lens basics
DSLR lens types | Composing & focusing with a DSLR
Buying an interchangeable lens can be as difficult as deciding which brand DSLR to get. Not only is the number of lenses staggering, but the cost of some is enough to take your breath away.
Here's what I've learned thus far.
DSLR kit lens
Entry level digital single lens reflex cameras come with an interchangeable lens called a kit lens, though the body can be purchased without the lens. Most kit lenses are zoom lenses, which range from wide angle to mid-telephoto.
A kit lens is made well but certainly not as well made as intermediate and pro grade lenses. A kit lens does not provide the same level of image quality as more costly lenses, and internal focus mechanisms may not be as quiet. Kit lenses may also lack features such as a distance scale, useful for focusing manually.
But that does not mean kit lenses are junk. They are certainly far better than lenses found on most compact digital cameras.
Lens mount
The lens mount is the connection point, either mechanical or electrical, between a camera body and a lens. The lens mount is different for every brand camera. so lenses made for one will not fit on a camera made by a different manufacturer. In addition, lenses used with a 35mm film cameras may not work with a digital single lens reflex camera or visa versa.
Maximum aperture
Maximum aperture refers to the widest opening known as f-stop of a lens. It is particularly important to know the maximum aperture of a lens if you take a lot of low light photography. A low f-stop (eg f/1.4) is considered "fast" because it will let more light onto the lens than a slower one. Fast lenses usually cost a lot more money than slow lenses.
Zoom creep
Some zoom lenses may extend or retract under their own weight, depending if a lens is held upwards or downwards. Some lenses have locking friction rings to prevent zoom creep.
Image stabilization
Not all DSLR lenses have Image Stabilization. If a camera body has built in IS, buying an image stabilized lens is unnecassary. It may also be unnecessary for lenses with short focal lengths and/or are considered fast.
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