Why "infinity focus" mode?

Discussion in 'Digital Photography' started by Eolake Stobblehouse, Dec 12, 2004.

  1. Why do cameras have an "infinity focus" mode? Is it only for when you
    shoot through glass or a mesh, or might there be other reasons the
    camera has trouble focusing on infinity?
    Eolake Stobblehouse, Dec 12, 2004
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  2. Many cameras have problems focussing when it is dark.

    Roland Karlsson, Dec 12, 2004
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  3. Eolake Stobblehouse

    Wright Guest

    Not sure that I fully understand your question, but a camera/lens focus on
    infinity can change based on atmospheric conditions and temperature changes
    - thus the need to allow some degree of change in infinity focus.
    Wright, Dec 12, 2004
  4. Scenery at night where the autofocus might work poorly (e.g., expanses of
    city lights, where the autofocus zone happens to be empty)...

    Astronomical photography...

    Photography through scientific instruments where you want to aim the camera
    into the eyepiece, with the camera's focus locked...

    And if you are going to have manual focus at all, infinity has to be the end
    of its range.
    Michael A. Covington, Dec 12, 2004
  5. Eolake Stobblehouse

    SleeperMan Guest

    That's true, but ut has very little todo with infinity focusing... You can
    have total darkness and you still can't get a focused picture if you set the
    camera to infinity and try to shoot an object, 1 or 2 m away...
    It's meant for distant objects, where camera can't focus any longer just
    because of to long distance and also because at that long distance it's no
    longer any difference to change focus anymore. You can't measure 100 m if
    the camera can measure only up to 50m...
    SleeperMan, Dec 12, 2004
  6. Eolake Stobblehouse

    SleeperMan Guest

    AS said elsewhere, you can't solve this by infinity - there are two
    different things...if the camera can't focus in the dark, you must help
    yourself by other things, like pointing laser beam into the object, or very
    narrow hand torch...
    again not hte same thing - above claim would be named manual focus, not
    infinity. Did you ever try to set the camera to infinity and shoot an object
    (even through glass...) which is 1 m away? i guess not...

    at last true
    SleeperMan, Dec 12, 2004
  7. Hmmm . I think we are talking about different
    things. The infinity focus setting I have seen
    on cameras means a manual setting of always infinity.
    And I use that setting very often.

    Cameras with small sensors have a rather large
    DOF and if you want to take a night view then
    almost everything is sufficiently far away
    to focus on infinity.

    Roland Karlsson, Dec 12, 2004
  8. Still - I think it is you that have misundertood.
    The "infinity focus mode" is probably just that,
    a manual setting at infinity. My and Michael's
    answer are both based upon that assumption.

    So - OK - original poster: what "infinity focus
    setting" are we talking about? Sleeperman's or
    Michael's and mine?

    Roland Karlsson, Dec 12, 2004
  9. Eolake Stobblehouse

    Ron Hunter Guest

    The mode setting conserves battery power, and time since the camera can
    just skip the autofocus process entirely. I use if for landscape
    pictures, or any subject greater than 50 feet from the camera.
    Ron Hunter, Dec 12, 2004
  10. Eolake Stobblehouse

    SleeperMan Guest

    True. In fact, i often wondered, how long means "infinity" - i have Canon S1
    IS and i even wrote to Canon and they didn't answer anything in numbers. So,
    i still wonder, how long can this (or any other) camera focus before it
    locks in infinity?
    SleeperMan, Dec 12, 2004
  11. Eolake Stobblehouse

    SleeperMan Guest

    Maybe i was a bit too generous with numbers - i think 50 m is already
    infinity for all cameras. Maybe 2 m is better...
    And - sure, infinity settings - you must set it manually, but it's still
    not the same as manual focusing, which is meant for various reasons, like
    several shots at same distance etc. I think my Canon S1 doesn't even have
    infinity mode, but focus lock instead, so i can lock focus wherever i want.
    But set focus in total darkness can result in out of focus shots, if these
    shots are taken from close.
    First firmware of S1 was very bad in low-light focusing, so i helped myself
    with small hand-held laser pointer - i attached one of filters (i believe it
    was heart) and then i pointed it to an object i wanted to shoot, locked
    focus, and shoot. Results were quite excellent. But now all this is improved
    with firmware upgrade (luckily).
    SleeperMan, Dec 12, 2004
  12. Eolake Stobblehouse

    SleeperMan Guest

    i second that. As said, a man must MANUALLY set this infinity mode. But
    Michael wrote

    'Photography through scientific instruments where you want to aim the camera
    into the eyepiece, with the camera's focus locked...'

    Which is not quite clear - he is right about locked focus, but not always in
    infinity point.
    SleeperMan, Dec 12, 2004
  13. Eolake Stobblehouse

    Jim Kelly Guest

    Taking photos through an aircraft canopy! Stops the camera trying
    to focus on the canopy . . instead you get to focus on the


    Why do cameras have an "infinity focus" mode? Is it only for when
    shoot through glass or a mesh, or might there be other reasons
    camera has trouble focusing on infinity?
    Jim Kelly, Dec 12, 2004
  14. Eolake Stobblehouse

    dj_nme Guest

    At one stage I had to take photos of samples under a microscope.
    I was using a Minolta XG-2 with 50mm f/1.4 and 400 ASA Kodak film.
    It didn't seem to matter what distance I focussed the lens to, as it was
    always in focus if the lens was rested against the eyepiece, as long as
    the image was sharp when viewed normaly with the naked eye throught the

    Perhaps that is the sort of situation that applies to the quote above?
    dj_nme, Dec 12, 2004
  15. Eolake Stobblehouse

    SleeperMan Guest

    Good question...
    SleeperMan, Dec 12, 2004
  16. Eolake Stobblehouse

    SleeperMan Guest

    good one!
    SleeperMan, Dec 12, 2004
  17. For airplanes in the air it can save focus hunt time (and focus will
    fail if the airplane isn't over a sensor). Same could happen with
    David Dyer-Bennet, Dec 12, 2004
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