ianb Posted October 21, 2004 Share Posted October 21, 2004 I am going to buy a drebel and all these canon lenses are "USM"... What does it mean? Thanks,Ian Link to comment Share on other sites More sharing options...
jimvanson Posted October 21, 2004 Share Posted October 21, 2004 USM equals <b>U</b>ltra <b>S</b>mall <b>M</b>idgets. They are held prisoner in each lens. Their duty is to move the lens elements back and forth thus focusing the lens -- Truth! Link to comment Share on other sites More sharing options...
ianb Posted October 21, 2004 Author Share Posted October 21, 2004 Wow - they should unionize. Link to comment Share on other sites More sharing options...
gforce Posted October 21, 2004 Share Posted October 21, 2004 It stands for Ultra Sonic Motor. It's used to indicate lenses with built in focusing motors. USM is also used to refer to the Unsharp Mask in an image editing program. Link to comment Share on other sites More sharing options...
michaelkh Posted October 21, 2004 Share Posted October 21, 2004 The midgets thing is just an internet rumour. It actually stands for Unusually Small Mice. (In little wheels, driving the lens movements). The real answer is, I think, 'ultrasonic motor' - that is, the lens has its own (quiet) AF motor rather than relying on the one on the camera. See http://www.photo.net/equipment/canon/lens-motors Link to comment Share on other sites More sharing options...
michael_gordon1 Posted October 21, 2004 Share Posted October 21, 2004 http://photonotes.org/articles/beginner-faq/lenses.html#lensmotor Link to comment Share on other sites More sharing options...
michaelkh Posted October 21, 2004 Share Posted October 21, 2004 As anyone who watched Bagpuss as a kid will surmise, the Unusually Small Mice are very militant. When your lens specification says 'seven elements in four groups', this is actually a stealthy political comment. Link to comment Share on other sites More sharing options...
__hank_boneroneo1 Posted October 21, 2004 Share Posted October 21, 2004 The motors in drebels are good. I have many hours on mine with lots of cutting and grinding. Link to comment Share on other sites More sharing options...
awindsor Posted October 21, 2004 Share Posted October 21, 2004 G Froce, all Canon EF lenses contain focusing motors. On some old and some cheap lenses you have AFD which stands for A Failing Diplodocus. They are powered by a single small and tired dinosaur. The result is much slower and lounder focusing. What do you expect ? The focusing motor is a dinosaur ! Link to comment Share on other sites More sharing options...
jimvanson Posted October 21, 2004 Share Posted October 21, 2004 I thought <b>F</b>ailing <b>D</b>iplodocus was the FD line of lenses used back in the dinosaur days of manual focus. Link to comment Share on other sites More sharing options...
awindsor Posted October 22, 2004 Share Posted October 22, 2004 Speak for yourself. On my manual focus lenses the focusing engine is an Adonis ;) They are called MF lenses for Muscular Focuser ! Link to comment Share on other sites More sharing options...
grahams Posted October 22, 2004 Share Posted October 22, 2004 I thought it meant Ultra Sharp Mechanism.... Link to comment Share on other sites More sharing options...
bacsa Posted October 22, 2004 Share Posted October 22, 2004 no,no, you all got it wrong. It stands for Ultra Smart Marketing, nothing more. Link to comment Share on other sites More sharing options...
J.W. Wall Posted October 22, 2004 Share Posted October 22, 2004 Un Solved Mystery. Link to comment Share on other sites More sharing options...
gpdno Posted October 22, 2004 Share Posted October 22, 2004 <i>As anyone who watched Bagpuss as a kid will surmise, the Unusually Small Mice are very militant.</i> <p> Quite similar in behavior to the ROUS's (Rodents of unusual size) that inhabit the fire swamp. Link to comment Share on other sites More sharing options...
joshchapman Posted October 22, 2004 Share Posted October 22, 2004 All canon AF lenses have the focusing motor in the lens (rather than the camera in some other manufacturer's older lenses). USM(UltraSonic Motor) is a type of motor that's faster, and much quieter than canon's other offering, AFD (ArcForm Drive). Which is not to say that AFD lenses aren't without their merits(some very good wide angle prime lenses are only available with AFD), but USM is certainly the better option. Link to comment Share on other sites More sharing options...
john_maur Posted January 7, 2005 Share Posted January 7, 2005 I just love to do this: REALLY, SANTA IS NOT REAL.. <br><br><br><br><br><br><br><br><br><br><br><br><br><br> <br><br><br><br><br><br><br><br><br><br><br><br><br><br> sorry Link to comment Share on other sites More sharing options...
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