Results 1 to 16 of 16

Thread: Focussing speed.

  1. #1

    Default Focussing speed.

    Hi, I have just gotten a 70-300 lens. From the 70mm, and tried to zoom on a contrasty object, quite ok. But once I up to 300mm, it keeps on focussing. Is this normal?
    TIA, wong

  2. #2

    Default Re: Focussing speed.

    Sorry, but what lens are you using? Nikon? Canon? Minolta? 3rd party? different lens and different cam have different capability.

  3. #3

    Default Re: Focussing speed.

    canon 70-300 IS USM. Also, i noticed the focussing is like very slow. I though USM should be almost instant? Can take more than 1 second to zoom from nearest to infinity. Is that too long???

  4. #4

    Default Re: Focussing speed.

    I don't think its the "true" ring type USM, should be the inferior micro USM.

  5. #5

    Default Re: Focussing speed.

    here's a lens review
    http://www.the-digital-picture.com/R...ns-Review.aspx

    "The Canon EF 70-300mm f/4.5-5.6 DO IS USM Lens is not a fast lens to begin with, but stopping down to f/8 or so makes it very slow. Image Stabilization helps greatly, but not if you want to stop non-panning action. "

    hope it helps

  6. #6

    Default Re: Focussing speed.

    Quote Originally Posted by ynot
    here's a lens review
    http://www.the-digital-picture.com/R...ns-Review.aspx

    "The Canon EF 70-300mm f/4.5-5.6 DO IS USM Lens is not a fast lens to begin with, but stopping down to f/8 or so makes it very slow. Image Stabilization helps greatly, but not if you want to stop non-panning action. "

    hope it helps
    Nope it doesn't help. I think u misunderstood the meaning of fast in here. You also got my lens model wrong But thanks anyway

  7. #7

    Default Re: Focussing speed.

    Quote Originally Posted by n0d3
    I don't think its the "true" ring type USM, should be the inferior micro USM.
    I think true ring or false ring, as long as is USM, ultra sonic, should be ultra focussing speed right? And not take 1.5 second to focus from 1 end to another?

  8. #8

    Default Re: Focussing speed.

    Nvm...disregard that I asked....maybe night time is not a good time to test. I'll try when day breaks. Thanks

  9. #9
    Senior Member
    Join Date
    Aug 2005
    Location
    Singapore, CanonGraphers.org
    Posts
    3,157

    Default Re: Focussing speed.

    Quote Originally Posted by ynot
    here's a lens review
    http://www.the-digital-picture.com/R...ns-Review.aspx

    "The Canon EF 70-300mm f/4.5-5.6 DO IS USM Lens is not a fast lens to begin with, but stopping down to f/8 or so makes it very slow. Image Stabilization helps greatly, but not if you want to stop non-panning action. "

    hope it helps
    I dont think it his version of the lens. coz this one has the Ring-USM.I think what the author meant with his 'very slow' is the apperture, and not focussing speed.
    Night time is also not a good time to test focussing, it will tend to hunt.
    And dosent mean USM mean ultra fast focussing.Hope you will do more research into this before you make a comment.Micro USM and Ring USM is different.IMO, micro USM is just a cheap excuse for Canon to increase the price of the lens.

  10. #10

    Default Re: Focussing speed.

    Quote Originally Posted by wong1979
    I think true ring or false ring, as long as is USM, ultra sonic, should be ultra focussing speed right? And not take 1.5 second to focus from 1 end to another?
    Wrong. Only the true ring type USM will give you that silent/fast focusing speed.

  11. #11
    Member
    Join Date
    Aug 2005
    Location
    Singapore, Singapore, Singapor
    Posts
    1,109

    Default Re: Focussing speed.

    Quote Originally Posted by wong1979
    Hi, I have just gotten a 70-300 lens. From the 70mm, and tried to zoom on a contrasty object, quite ok. But once I up to 300mm, it keeps on focussing. Is this normal?
    TIA, wong
    Read through the posts.

    Usually, focussing depends on the contrast and available light. the lens have difficulty focusing if they can't 'find' the spot to focus on.

  12. #12
    Member
    Join Date
    Oct 2005
    Location
    Bt. Timah
    Posts
    1,354

    Default Re: Focussing speed.

    If you have problems focusing a night, hook up an external flash and use the AF-assist beam to help your camera focus. Has limited range but its useful.

    And SLR lenses generally have difficulty focusing in low light situations as there's not enough contrast for AF to get a fix. Nothing to do with what kind of focusing motor it uses. If you want to test the speed, do it in broad daylight.

  13. #13

    Default Re: Focussing speed.

    Do you mean the focussing is slow as in it 'hunts' back and forth, or u mean it moves really slow like a toy car with weak batteries? You may want to take it to the shop to test another copy of the same lens. If shop don't let you change then worst case, bring to canon for checking/servicing.

  14. #14

    Default Re: Focussing speed.

    Quote Originally Posted by benedium
    Do you mean the focussing is slow as in it 'hunts' back and forth, or u mean it moves really slow like a toy car with weak batteries? You may want to take it to the shop to test another copy of the same lens. If shop don't let you change then worst case, bring to canon for checking/servicing.
    Yup, like ur toy car analogy. But I think it should be normal, I just got the impression that USM must focus from 1 end to another fast.

    This is what I do with mine. I aim at someting of the same color, and it takes ruffly 1 sec ++ to reach to the other end. Normal?

  15. #15
    Senior Member
    Join Date
    Jan 2005
    Location
    Oulu, Finland, Finland
    Posts
    6,299

    Default Re: Focussing speed.

    Quote Originally Posted by n0d3
    Only the true ring type USM will give you that silent/fast focusing speed.
    Yes. not all canon lenses with the word 'USM' means fast and silent focusing. the ring type one's faster. my 17-40 focuses quite fast. i think it's almost negligible. perhaps i'm exaggerating! :P but 1 sec++ is abit too long.

    maybe u want to read this review?

    http://www.the-digital-picture.com/R...ns-Review.aspx

    not too sure if urs is this model.

    to quote a paragraph,

    But, Ring USM (Ultrasonic Motor) is not part of the package. Improvements in the CPU and AF routines help in the focus performance increase according to Canon. Accuracy is often more important than speed. Good thing as actual performance of the Micro USM shows accuracy to be very good but speed is just OK - not as good as I had hoped.
    Last edited by drumma; 17th December 2005 at 09:08 AM.

  16. #16

    Default Re: Focussing speed.

    perhaps I'm being too panicky. Daytime testing seems good enough

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •