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USM.
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Could someone explain to me the advantage of USM on Canon lens.
Does USM produce a sharper picture like IS?
If I used an USM lens on my 350D instead of an ordinary Canon Lens, in what way would my pics be improved?
Sorry if this Q came up before: I did a search but couldn’t find what I was asking for.
USM is Ultrasonic Motor, ie the motor in the lens which controls autofocus. It probably won’t have much effect on your sharpness, other than that autofocus accuracy might be a bit more accurate. What it will give you is fast, silent AF. Also, USM lenses (though I think not all of them) can pass the focusing distance to the flash to help flash exposure, and will also allow manual override when AF is engaged (not a good idea to try this on a normal lens). I think the latter two may only apply to the ring type USM
John
Thanks very much John for that. It’s as I thought.
By the way. Looked at your flickr album. Lovely. You must have had a brill time in Argentina.
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