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Thread: USM Vs Non USM

  1. #1

    Question USM Vs Non USM

    Hi

    I was wondering about the difference of picture quality of USM lens and a non-USM lens.
    I am about to get a 75-300mm lens and was wondering whether it would make a real diff if the lens was a USM one.
    btw , my camera is a EOS300 with 28-105 II USM lens.

    Other than the EF lens(i.e Non- USM) being noisy , does it take a eternity for this lens to focus ?

    Please enlighten me .

    Thanx in advance.

    Cheers

  2. #2
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    USM lens has better lens constructio. More worth to get the USM

  3. #3

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    Originally posted by SniperD
    USM lens has better lens constructio. More worth to get the USM
    nonsense....

    the optical quality is the same. construction is the same. the diff is only the motor driving the auto-focusing

  4. #4
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    USM useless to me, but to those doing animal shots, Ring USM is a god send. If using normal AF without Ring USM, the animal would be alerted by the AF motor before a shot can be taken. Note: AF is the no.3 noise producer in a SLR. The loudest is the mirror slap, the second is the auto film advance mechanism.

    Basically the lens construction is the same if both the USM and non USM lenses are belonging to the same series.


  5. #5

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    USM or non USM will not affect optical quality.

    As far as the 75-300mm goes, non-USM is ALMOST as fast as USM, so it may not be worth the extra few bucks for USM (except to improve resale value). But the IS might come in useful, especially for that lens. Just to confuse you, you can improve sharpness with photoshop using USM (unsharp mask, not ultrasonic motor), but not remove motion blur, which you can get easily without the IS.

  6. #6
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    Originally posted by jasonpgc
    USM useless to me, but to those doing animal shots, Ring USM is a god send. If using normal AF without Ring USM, the animal would be alerted by the AF motor before a shot can be taken. Note: AF is the no.3 noise producer in a SLR. The loudest is the mirror slap, the second is the auto film advance mechanism.

    Basically the lens construction is the same if both the USM and non USM lenses are belonging to the same series.

    Use MF. No noise. Better still, MF coupled with a Leica rangefinder camera. Quiet shutter. And if you wind slowly, very slowly, not much noise either. Catch is, you're limited to max 135mm.

    And yes, USM vs non-USM and AF-S vs non AF-S has no difference in image quality.

    Regards
    CK

  7. #7

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    Thanx for the reply.

    Might consider a non UMS lens.

    Cheers
    Ericana

  8. #8

  9. #9

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    Originally posted by Ericana
    Thanx for the reply.

    Might consider a non UMS lens.

    Cheers
    Ericana
    Why ? Just to save a few bucks ?
    It's usually better to get a USM lens, because the AF is usually faster and quieter, resale value is better, and it also allows you to focus manually should the AF fail to lock on target, without having to switch to manual focus mode.

    A quick primer : Canon uses 3 main types of AF mechanism in their lenses. AFD (Arc Form Drive) lenses are the oldest, and are somewhat noisier. The 50mm/f1.8 is one such lens. However, some of their older professional lens are also AFD, and are actually very fast and quiet too. An example would be the very good 80-200L/f2.8, which I happen to own. The cheaper AFD lenses are slower and noisier.

    The second AF type is micro motor. It is usually marketed by Canon as USM, but it is not the "real" USM that Canon is famous for. An example of a lens in this group is the 75-300 ( IS and non-IS ). This is "USM for the masses" kind of USM.Quieter then AFD, but slower and much cheaper than Ring Type USM. This is used in the mid to lower range lenses, usually around $300-$500 type.

    The last and ultimate type is the Ring Type USM. This is the one that Canon built it's name on. This one is quiet, fast, and allows full-time manual focus. Lenses using this include the very popular 70-200L/f2.8, 28-105 and 28-135IS. Most of the mid to high end lenses ( those that costs > $500 ) use this type of motor.

    So, if given a choice, it's usually best to op for the Ring Type USM, followed by micro motor, and AFD last.

  10. #10
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    BUY! BUY! BUY!

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