So You Are Going to Buy a New Lens

If you own a DSLR (Digital Single Lens Reflex) camera, then one of the purchases you will eventually want to make is another lens either to replace the kit lens that came with the camera or to complement it. For the most part, kit lenses are very good for the average amateur. But they have limited range, most being about 18 - 55 mm. This is a 3X zoom. How do you figure it out? Take the large number (55) and divide it by the small number (18). The answer is very close to 3, thus the 3X zoom.
There are a number of things that affect the cost of a new lens:

* What's the zoom range? Or, is it a "prime" lens - one which does not zoom?
* What's the maximum f stop or aperture opening?
* Does it have image stabilization? (Some manufacturers - Sony [ex Minolta], Pentax and Olympus - build stabilization into the camera rather than the lens.)
* Is it a "Pro" lens - which usually means it is made with low dispersion glass?
* Who is the manufacturer? Lenses made by the camera makers are generally more expensive than "3rd party" lenses made by companies like Sigma, Tokina and Tamron.