lens terminology primer needed

[jimwong]

Can someone give me a primer on Canon lens terminology. It seems some Canon lenses have the "L" designation, some have "USM" some have "IS" and some have a roman number such as II. I have one of the lens which has no designation which I think is the cheap version. Can someone give me a primer as to what each means and how it affects quality, sharpness, and cost.

[Cal Maier]

Jim,

Hopefully, this will answer some of your questions about the designation of Canon EF lenses.

"L" series lenses are manufactured with the highest quality lens elements, and are usually the sharpest glass that Canon makes, some models are rated as the sharpest available from any manufacturer.

"USM" designates that the lens auto focus is controlled by a Canon Ultra Sonic Motor(a faster & quieter motor). Almost all "L" series and quite a few regular series lenses are USM lenses.

"IS" stands for "Image Stablizer". These lenses have an extra stablizing motor that compensates for camera shake or movement, allowing the user to hand-hold the lens in lower light conditions, or to hold a long focal length steady without resorting to a monopod or tripod.
Don't ask me how it works just take my word that it works very well. Some "L" and non-L lens are manufactured with IS. Most are quite sharp, some are very sharp.

"II" or "III Series lenses are later versions of a particular lens, eg. EF 50mm /1.8 II. is a newer version of the EF 50mm/1.8 lens. It is also made of less expensive materials than the original model, but is still rated as being quite sharp for the cost of the lens.

Some older models of EF "L" series lenses did not have USM but were still very sharp glass, although the focus speed was not as fast as the newer USM models.

Here is a site that has rated many of the EF lenses as to how sharp they are www.photodo.com
This is a good site to refer to if you want to check on a particular model, although they have not rated every EF lens, there is a good selection available.

Hopefully this will help clear up some questions for you.

BTW you didn't mention the model of the lens that you have, if you would like to know a bit more about it let me know and I'll try to help out.

Cal