Holy ****atauke Mushrooms! Some Questions About my Temporary Toy

Discussion in 'Digital Discussion & Q&A' started by PhilGarber, Jun 29, 2009.

  1. PhilGarber

    PhilGarber TPF Noob!

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    EDIT-Posted some photos taken with the lens. I know, the noise levels are terrifying.

    Hi-

    Behold, my lovely rental! This baby from Lensprotogo is a 70-200mm 2.8 IS 'L' Lens. After putting my camera around my neck, I can see where all the bad jokes come from:confused:.

    Here are my few questions, please keep in mind this is my first IS or 'L' lens.

    1: What's the difference from IS mode 1 and 2?

    2: What's does it mean to focus at infinity? I've heard this term before. \

    3: What does the switch that says 1.4m-Infinity and 2.5m-infinity mean?

    4: Why does the focus ring work normally even with AF on?
     

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    Last edited: Jul 13, 2009
  2. SrBiscuit

    SrBiscuit TPF Noob!

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    i dont have any experience with canon, but i can answer #4.

    it makes it much more convenient to make fine adjustments without having to switch to manual mode. i have it on my 18-70, and i like it...i dont use it often, but it;s nice to know it;s there.

    thats a sweet lens.
    have fun!
     
  3. Dylan-Fishman

    Dylan-Fishman TPF Noob!

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    Zebra camera! can't answer any of those questions.... sorry. Sweet lens though
     
  4. PhilGarber

    PhilGarber TPF Noob!

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    Thanks Biscuit!
     
  5. PhilGarber

    PhilGarber TPF Noob!

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    Thanks Dylan. Just wishin' it were mine. :(
     
  6. kundalini

    kundalini Been spending a lot of time on here!

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    This should reduce the AF hunt if your subject is typically between 1.4M to infinity or 2.5M to infinity.
     
  7. PhilGarber

    PhilGarber TPF Noob!

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    You've lost me.. It takes less time to auto focus on those setting when the lens is a certain distance away?
     
  8. musicaleCA

    musicaleCA TPF Noob!

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    Basically. A quick low-down on how auto-focus works might help.

    Quoted from here.

    The process of autofocusing generally works as follows:
    (1) An autofocus processor (AFP) makes a small change in the focusing distance.
    (2) The AFP reads the AF sensor to assess whether and by how much focus has improved.
    (3) Using the information from (2), the AFP sets the lens to a new focusing distance.
    (4) The AFP may iteratively repeat steps 2-3 until satisfactory focus has been achieved.

    "Focus hunting" is when the AFP gets stuck in the iterative process of steps 2-3. This happens when focusing on a very low-contrast object (say a blank white wall, or a matte black surface), and happens more often in really low light.

    Focusing at infinity is when the lens if focused at its hyperfocal distance. It is the distance at which all objects beyond that point can be brought into acceptable focus. For instance, if you are shooting a landscape, you would focus at infinity, and that should bring everything beyond the lens' hyperfocal distance into focus; the aperture controls the DoF behind (toward the camera) the hyperfocal plane in this case.

    As for focus working all the time, you forgot that it's also a USM lens. That stands for "ultra-sonic motor". The design allows for you to manually focus all the time, so if AF messes-up, you can fix it quickly. It's also hella fast compared to previous focusing mechanisms. Also, the focus ring on the outside of the lens doesn't move while auto-focusing.

    As for different IS modes, I'm clueless because I've never owned a lens with more than one IS mode, but my guess is that one mode may give more stops of IS at a cost; perhaps it eats more power or degrades IQ a bit...or...something. I say read the manual for that one.

    Oh, and as for the term "L", it just means something along the lines of "luxury" or "ludicrously expensive". :greenpbl: It's Canon's way of saying that the lens is their cream of the crop; that great care and attention was put into its design and manufacture to give it the best IQ possible. They also come with lens hoods included, unlike other Canon lenses where the hood must be bought separately (in the case of the uber-long lenses, like the 300mm and 400mm lenses, the hood is actually made by hand, because it's not cost-effective to create them en-masse, as they sell so few of the lenses; that makes the hoods absurdly expensive to replace).
     
    Last edited: Jun 29, 2009
  9. PhilGarber

    PhilGarber TPF Noob!

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    So.. focusing at infinity is fancy DoF? I feel stupid.:(
     
  10. PhilGarber

    PhilGarber TPF Noob!

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    Thanks for the time spent on the reply, by the way!
     
  11. Soocom1

    Soocom1 TPF Noob!

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    OK I have the 70-200 F4. ( About a full pound lighter and it does not have the IS on it), BUT here is what the Canon dealer instructed me on when I purchased the lens a short time ago.

    IS Mode 1 is for Vertical and Horizontal shake.
    Mode 2 is vertical only.

    I.e. 1 is good for hand held, 2 is good for tripod-monopod mounted lenses.

    The 1.4 and 2.5 is actually designed for the focus distance.

    1.4 m is for focusing on anything closer than 1.4 meters all the way to infinity.
    The 2.5 m is for focusing in on subjects greater than 2.5 meters all the way to infinity.

    Yes the focus ring WILL work in AF mode, but not advised. It can damage the teeth inside the mechanism. It is best to just switch to MF if that is what you intend to do.


    P.S. It is best to keep the lens mounted on a tripod/monopod because of the weight.

    P.P.S. Watch the weight of the lens, this thing CAN and WILL damage the mounting lugs on the camera if you DO NOT either mount the lens on a tripod, or carry the camera/lens w/o
    supporting the lens someway.
     
  12. JamieR

    JamieR TPF Noob!

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    I was considering renting one myself.

    How much did it cost you and how long do you have it for?
     

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hyperfocal point is 1.4m, this is not on focus ring