1 page lens designation "dictionary"

[jimsolt]

Whenever I follow a discussion of "what lens is good or best" I quickly get confused by the lens designations -- EF, EF-S, USM, ETC.

Is there somewhere a one page document that explains what these designations mean?

And, dare I ask more, how one variety does better than others?

Thanks for helping me understand what you are talking about.

Jim

[HKFEVER]

Check out Canon's website. Their lens catalogue have a lot of details.

[Longwatcher]

I thought we had one of these as a sticky, but I can't find it anymore.

EF and EF-s are designations for the type of lens mount. FD was the previous series.
all EF lenses will fit all current Canon SLR cameras.
EF-s lenses will only fit newer APS-C (1.6x) format cameras (300D, 20D, 350D)
FD mounts only fit older Canon cameras.
There are adapters for FD lenses to EF cameras, but they are getting harder to find.

USM and AFD are the type of mechanisms in the lens for auto focusing.
USM = ultrasonic motor and is quieter then AFD or MM.
AFD = Arc Form Drive
MM = micro motor

"L" stands for luxury (It usually means, but not always, the best of Canon's lenses)

IS = Image Stabilization (should be plain what this is)

f=maximum aperture (largest opening the lens can attain - smaller f# is usually better)
If you don't know what aperture means then you need to read a book on basic photography.

More information on these technologies can be found at

http://www.canon.com/camera-museum/

which has all sorts of neat information on the cameras, lenses, and technology behind them. It seems to get updated quarterly.

Hope that helps,

[RJSorensen]

The 10D won't take a EF-S lens, I think you are referring to the 20D which will.

[jimsolt]

I thought we had one of these as a sticky, but I can't find it anymore.

EF and EF-s are designations for the type of lens mount. FD was the previous series.
all EF lenses will fit all current Canon SLR cameras.
EF-s lenses will only fit newer APS-C (1.6x) format cameras (300D, 10D, 350D)
FD mounts only fit older Canon cameras.
There are adapters for FD lenses to EF cameras, but they are getting harder to find.

USM and AFD are the type of mechanisms in the lens for auto focusing.
USM = ultrasonic motor and is quieter then AFD or MM.
AFD = Arc Form Drive
MM = micro motor

"L" stands for luxury (It usually means, but not always, the best of Canon's lenses)

IS = Image Stabilization (should be plain what this is) . . .
Hope that helps,
Thanks, this helps a lot.
I have a good understanding of the basics. It's the variety of types that is hard for me to keep track of.
For instance, (correct me if I'm wrong) I think the EF lenses as you say will fit all the current SLRs including the soon to be released new Rebel, so why would I want to buy an EF-S? Could it be (if you read crystal balls) that Canon SLRs of the future would require EF-S, or is there another "advantage" that I don't know about.

JIM

[Longwatcher]

The 10D won't take a EF-S lens, I think you are referring to the 20D which will.

oops....fixed via edit. Thanks fot the catch.

[Longwatcher]

The reason for the EF-s series lenses should be that they are lower cost then an equivilant EF lens since they don't need as much glass given the smaller size.

It is much cheaper to get a 10-22 EF-s lens ($800) then a 16-35 EF lens ($1360) which is the equivilant lens. The 10-22 EF-s lens on an APS-C camera will act like a 16-35 EF lens does on a Full Frame (FF) 35mm camera in terms of field of view.

My theory gets shot down with the EF-s 17-85 IS ($600)which works on an APS-C sensor like a EF 28-135 IS ($400) does on FF. But then a 28-135 on a APS-C camera works like 45-216 which might not give you the same flexability. [this is evidence by the fact that I needed to get a 16-35 for my D60, because the 28-135 was not wide enough with that camera (APS-C size sensor)] Had the EF-s 17-85 IS been available (and fit) I probably could have gotten away with that and my 70-300 IS and had all I needed. Instead I bought a 16-35L discovered "L" and felt I could not get a lesser lens after that [17-40 not available then]].

So EF-s lenses give the APS-C camera owners what they were missing from the EF series lenses because of the sensor size difference.

As to whether they are a good value or not, that is up to you. Do take into account though that eventually Canon "may" go to full frame with all of its cameras although it will probably be at least 5 years before this happens so will you upgrade from APS-C to FF before then? if not the EF-s are a good value if you will be then they probably are not.

Just my opinion,

[robertwgross]

If you have only one of those few digital cameras that can use EF-S, then that is a good choice since they are cheaper.

On the other hand, if you have a Canon EOS film camera and/or one of the other EOS digitals, then those use only EF. So, the EF lens can be applied to a wider number of camera users, even if it costs a little more. I happen to have both of these, so I'll likely stick with EF only.

---Bob Gross---