Minolta 9Xi Focus Problem Revisited

Discussion in 'Minolta' started by Fred McKenzie, Dec 29, 2008.

  1. When I bought the Minolta Maxxum 9Xi many years ago, I got the 28-105mm
    f/3.5-4.5 Xi lens to go with it. Under certain conditions (I don't
    recall specifics) the camera would fail to autofocus, and would continue
    to search back and forth through the focus range of the lens. Does
    anyone have this combination of Xi body and lens, that remembers having
    similar problems?

    Moving forward in time, I found that all of my old Minolta lenses work
    well with a Sony Alpha 100 body, including the Xi lens. However, the
    new Alpha 900 body seems to have a similar focus searching problem with
    the Xi lens, when photographing certain scenes such as tree limbs or
    power poles against a clear sky, zoomed to 105mm.

    If anyone happens to have either a Maxxum 9Xi body or a Sony Alpha 900
    body and the Minolta 28-105 f/3.5-4.5 Xi lens, I would be interested in
    knowing if you can duplicate my problem of focusing "lines and twigs"
    against a clear sky.

    Fred
     
    Fred McKenzie, Dec 29, 2008
    #1
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  2. In article <>,
    "Nicholas O. Lindan" <> wrote:

    > The problem may be that the focusing spot(s) the camera is
    > using are _between_ the lines and twigs and all the sensor
    > is seeing is clear sky. Also, horizontal or vertical
    > (depending on the sensor design) twigs and lines
    > may give the AF sensor fits - imagine using a rangefinder
    > camera to focus on a horizontal power line. Try
    > putting a twig or line at a 45 degree angle through the
    > center of the frame and see if the camera can focus on that.


    Nicholas & Alan-

    I expect the problem is related to what you suggest, but the situation
    is not exactly like a horizontal power line. In one case, it is the top
    of a vertical power pole that has an assortment of large insulators and
    wires. In another case, it is foliage of a tree that is somewhat
    sparse, but contains leaves and twigs at various angles.

    The A900 focus system may be different from the A100. For the two
    specific scenes, the A900 always has (or had) the problem and the A100
    never has the problem, both using the same Xi lens. So far, the A900
    has not had the problem with any other lenses, and not with the Xi lens
    for other scenes.

    If a subject is closer than the closest focus point of a lens, or if
    aiming at a clear patch of blue sky, both bodies will fail to focus.
    But they each make one sweep through the focus range and stop trying.
    When the problem occurs, the A900 continues to sweep back and forth
    through its focus range until it is re-aimed in some other direction or
    I release the button.

    Per your suggestion, I went to try holding the camera at an angle. But
    today I was not able to duplicate the problem! It may have something to
    do with the angle of the sun or the fact that there are clouds today.
    I'll try again later.

    Fred
     
    Fred McKenzie, Dec 29, 2008
    #2
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  3. In article <>,
    Fred McKenzie <> wrote:

    > Per your suggestion, I went to try holding the camera at an angle. But
    > today I was not able to duplicate the problem!


    Trying later, the problem is now somewhat intermittent. Once it
    happened when zoomed to something less than 105mm. When it happens,
    holding the camera at a 45 degree angle either left or right, has no
    effect. However, changing the zoom now "upsets" the problem and it
    starts working again.

    When it is working normally, the camera has no trouble focusing on a
    horizontal telephone wire against a clear sky. Once it successfully
    focused on an airplane that was so small it was barely visible.

    I hope it is possible to isolate the problem to either the lens or the
    body while the body is still under warrantee!

    Fred
     
    Fred McKenzie, Dec 30, 2008
    #3
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