rr_ww

What does USM stand for and apart from cost, whats the difference between lenses with it and those without.


Thanks for reading.

Belf

Ultra Sonic Motor

They have quieter focussing motors in the lens basically.

rr_ww

Thanks very much mate. So basically not really worth it then. Or are they seriously noisy without it?

Actually can you point me at a good link for Canon SLRs, save messing you about with all my amateur hour questions

ChrisB

I thought another benefit was that they focus quicker?

{Retreats back into box}

Maddriver

not that noisy, but if you want to (say) photograph wildlife then & you don't want anything to make a noise and scare the wildfile off then a eltric motor wirring away is the last thing you want.


USM is also good for other situations where you want to be unobtrousive, like candids where you don't want to distract the subject, or a wedding where a noise out of place would really spoil an atmosphere.

AndyC_772

iTrader: (2)

Lenses with USM generally focus faster, and certainly focus more quietly than those without. Generally speaking, the lenses that are optically superior also tend to be equipped with USM as well. All Canon's current L-series lenses have USM.

Focus speed seems more dependent on the ability of the camera's AF sensors to tell when focus has been achieved, rather than the absolute speed of the motor - USM lenses can just hunt from macro to infinity faster than non-USM lenses if there's not enough light.

The best site I've found for advice on cameras and lenses is DPReview, which has a very active Canon SLR forum. If you're looking for a specific lens, post a few more details (either here or there) and I'll be happy to advise.

A.


[Edited by AndyC_772 - 10/27/2002 7:45:02 PM]

south-star

I have a Canon eos and i went for the USM lenses.If your gonna spend a few quid on a decent SLR i'd get the Canon lenses to go with it

Mufasa

I prefer laser sights on my MP5

P1Fanatic

lol @ mufasa!

MartinM

... there is also no direct mechanical connection between the motor and the lens (its all done with ultrasonics you see).

So, the camera can autofocus, but then it is possible to manually override the focus (should you want to) by grabbing the focus ring and turning it - which then doesn't have to also turn the motor through any physical gearing system

Damn clever these Japanese!

Luke

treat yourself to "Image Stabilizer"lenses. very nice in low light.

rr_ww

Cheers for all the replies people! Better do some research before splashing cash!

Thanks again

AndyC_772

iTrader: (2)

DPReview is a good place to start - there's a pretty good search function, so you should be able to find information on a particular lens that you're interested in that way. Don't believe everyone that says "if it's not L-series, it's not worthwhile" - although the L lenses are the best, there are some excellent others in the range too.

I have a Canon 28-135 IS (the first I bought, and an excellent all-rounder), 50 f/1.4 (very sharp, great for low light) and Sigma 15-30 (a bit prone to flare, but sharp and usefully wide on a digital SLR). (I have a couple of L-series telephotos too )

Andy.