Sony A100 focusing

Discussion in 'Digital Photography' started by jeffrey, Dec 22, 2006.

  1. jeffrey

    jeffrey Guest

    I have a Sony A100 DSLR and its focus is terrible in less-than-ideal
    conditions. In dim light (not even t-h-a-t dark), the flash flashes
    several times and takes several seconds to focus before the picture is
    taken.

    There is an indicator that comes on when the picture is in focus.
    Often times, the image appears to be in focus through the viewfinder
    but the focus indicator doesn't come on. If the focus indicator does
    not come on, the camera refuses to take the picture.

    This problem doesn't only happen in low light. I was on a plane ride
    and trying to take pictures of the ground. It was a cloudy day, but
    not too bad. Often times, the camera would not be able to focus on the
    ground, and refuse to take the picture.

    I have a small point-and-shoot digital camera that focuses better than
    this camera. Is this just a problem with my specific camera, or is the
    Sony A100 just bad at focusing?
    jeffrey, Dec 22, 2006
    #1
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  2. jeffrey

    ASAAR Guest

    On 21 Dec 2006 20:06:27 -0800, jeffrey wrote:

    > I have a Sony A100 DSLR and its focus is terrible in less-than-ideal
    > conditions. In dim light (not even t-h-a-t dark), the flash flashes
    > several times and takes several seconds to focus before the picture is
    > taken.
    >
    > There is an indicator that comes on when the picture is in focus.
    > Often times, the image appears to be in focus through the viewfinder
    > but the focus indicator doesn't come on. If the focus indicator does
    > not come on, the camera refuses to take the picture.
    >
    > This problem doesn't only happen in low light. I was on a plane ride
    > and trying to take pictures of the ground. It was a cloudy day, but
    > not too bad. Often times, the camera would not be able to focus on the
    > ground, and refuse to take the picture.
    >
    > I have a small point-and-shoot digital camera that focuses better than
    > this camera. Is this just a problem with my specific camera, or is the
    > Sony A100 just bad at focusing?


    I can only guess, and mine would be that the problem is not just
    with your specific camera. The A100 is based in part on Konica /
    Minolta designs, and their camera's AF performance often had
    problems. The A2 and A200 frequently misfocused, but unlike your
    A100, the focus indicator would come on when the camera was not
    accurately focused.

    Does your A100 manual describe the types of subjects help the AF
    system to focus as well as those that cause focusing problems? My
    manuals describe several, and subjects with well defined vertical or
    horizontal lines generally work well. You should try to avoid
    trying to focus on fur, smoke, very low contrast objects, etc.

    The AF assist you get from the flash obviously will only work for
    focusing on fairly close subjects. When trying to focus on the
    ground (while riding in a plane), you'd still want to try to
    prefocus on some suitable focusing subject and then after getting a
    good focus indication, reposition the camera to frame your intended
    subject. Vibration while flying probably makes focusing a bit more
    difficult. Your manual may not provide detailed information on the
    alternate photography modes, but as implemented by some
    manufacturers, some, such as "landscape" mode may prefocus to near
    infinity. If the A100 does this you might try using landscape mode
    to take pictures on the ground while flying. Other cameras offer
    Custom modes where you can preset many options including the
    focusing distance, which may be easier to use than trying to
    manually focus while flying. Did you try using manual focus?
    ASAAR, Dec 22, 2006
    #2
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  3. jeffrey

    Adam Smith Guest

    Never had a focusing problem but I don't use flash unless I really have to.
    The faster the lens the quicker the focus but please re - read the Manual.
    Those flashes you see are not all for focusing purposes.

    IBTW if you want to take a shot regardless of whether the camera thinks
    you're in focus or not
    you can do so by making a small change one of the Menus.

    You may find it helpful to read this cheap ebook
    http://www.friedmanarchives.com/alpha100/index.htm
    It helped me find my way around the camera.
    You can get a hard copy via Amazon.
    Adam Smith, Dec 22, 2006
    #3
  4. jeffrey

    ASAAR Guest

    On Fri, 22 Dec 2006 15:45:21 GMT, Adam Smith wrote:

    > Never had a focusing problem but I don't use flash unless I really have to.
    > The faster the lens the quicker the focus but please re - read the Manual.
    > Those flashes you see are not all for focusing purposes.


    If you are implying that the flash is used for other purposes such
    as anti-redeye or for exposure calculation you're probably correct,
    but that doesn't mean that the flash isn't also used for focusing.
    Whether it actually is used for focusing probably depends on whether
    there is a switch or menu setting that enables or disables AF assist
    and is needed in addition to the raising of the flash requirement.

    > The A100 has a pop-up flash on the top of the viewfinder prism, it is opened
    > manually by flicking it up. When raised the flash is approximately 90 mm
    > above the center of the lens, which is about 20 mm less than the Konica
    > Minolta 7D. The built-in flash unit has a guide number of 12 and a maximum
    > sync speed of 1/160 sec (1/125 sec with AS on). In a low light situation with
    > the flash raised the camera will strobe the flash to act as an assist lamp for the
    > AF system (it must be raised manually to perform this function).


    http://www.dpreview.com/reviews/sonydslra100/page5.asp
    ASAAR, Dec 22, 2006
    #4
  5. jeffrey

    jeffrey Guest

    Adam Smith wrote:
    > IBTW if you want to take a shot regardless of whether the camera thinks
    > you're in focus or not
    > you can do so by making a small change one of the Menus.


    Where can I find that function?
    jeffrey, Dec 22, 2006
    #5
  6. jeffrey

    jeffrey Guest

    It's hard to get sharp focus manually. I've taken shots with manual
    focus; when I view them on my computer, they were not very well
    focused.

    How can I set the flash for AF assist, but not to actually fire during
    the picture? When I open the flash, it automatically fires during the
    picture.

    ASAAR wrote:
    > Did you try using manual focus?
    jeffrey, Dec 22, 2006
    #6
  7. jeffrey

    Bill Tuthill Guest

    jeffrey <> wrote:
    > Adam Smith wrote:
    >> IBTW if you want to take a shot regardless of whether the camera thinks
    >> you're in focus or not
    >> you can do so by making a small change one of the Menus.

    >
    > Where can I find that function?


    I wouldn't recommend this function, which would be called "Shot Priority"
    instead of "Focus Priority" in the manual.

    I don't have a Sony A100 but have Minolta gear. When my SLR is using
    the flash to help focus in low light, it is very indecisive. That's why
    I changed a custom function to prevent use of flash-assist for focusing.
    Minolta (and I should hope Sony DSLR) have excellent low-light focus,
    better than Canon actually, but not with flash assist.

    Look for "Disable Auto Flash Popup" (or something like that) in the manual.
    Bill Tuthill, Dec 22, 2006
    #7
  8. jeffrey

    ASAAR Guest

    On 22 Dec 2006 11:29:23 -0800, jeffrey wrote:

    > It's hard to get sharp focus manually. I've taken shots with manual
    > focus; when I view them on my computer, they were not very well
    > focused.


    It's especially difficult focusing in dim light. Some people
    would simply use manual focusing to create a custom setting with a
    prefocused distance near infinity. Then they'd be able to use it
    anytime in the future without having to duplicate the manual
    focusing process. Obviously this wouldn't be very useful for closer
    shots, where the shallower depth of field would be a problem.


    > How can I set the flash for AF assist, but not to actually fire during
    > the picture? When I open the flash, it automatically fires during the
    > picture.


    According to Bill T. you wouldn't want to do this because it might
    lead to focusing problems. But if you really want to try, check the
    different flash options. Most cameras allow you to select choices
    from a menu or by pressing a button, that include Disabled,
    Automatic (the camera decides whether to flash or not), Enabled (the
    flash always fires) and possibly a few others. Depending on the
    mode used, not all of these options would be available, but that may
    help. For instance, Landscape Modes usually don't allow the flash
    to be used. If you can find a useful mode that either disables the
    flash or includes a Disabled flash option, then by manually popping
    up the flash, it may allow for AF preflashes to be used. Some
    cameras also have a global Enable/Disable option for AF preflashes.
    ASAAR, Dec 22, 2006
    #8
  9. Bill Tuthill wrote:

    > I wouldn't recommend this function, which would be called "Shot Priority"
    > instead of "Focus Priority" in the manual.
    >
    > I don't have a Sony A100 but have Minolta gear. When my SLR is using
    > the flash to help focus in low light, it is very indecisive. That's why
    > I changed a custom function to prevent use of flash-assist for focusing.
    > Minolta (and I should hope Sony DSLR) have excellent low-light focus,
    > better than Canon actually, but not with flash assist.
    >
    > Look for "Disable Auto Flash Popup" (or something like that) in the manual.
    >


    My A100 focuses just fine, under all conditions. It is an amazing
    camera. Once when I was in a cave in Ruby Falls, Chanttanooga Tennessee,
    I took a shot of my family in the dark. The camera flash pre-flashed
    once, the camera used it to focus, and then it took the shot perfectly.
    I had never seen that done before.

    GAry Eickmeier
    Gary Eickmeier, Dec 23, 2006
    #9
  10. jeffrey

    jeffrey Guest

    Bill Tuthill wrote:
    > I wouldn't recommend this function, which would be called "Shot Priority"
    > instead of "Focus Priority" in the manual.


    Where can I find this function? I can't find it in my manual, but I'd
    like to try it out.

    > I don't have a Sony A100 but have Minolta gear. When my SLR is using
    > the flash to help focus in low light, it is very indecisive. That's why
    > I changed a custom function to prevent use of flash-assist for focusing.
    > Minolta (and I should hope Sony DSLR) have excellent low-light focus,
    > better than Canon actually, but not with flash assist.
    >
    > Look for "Disable Auto Flash Popup" (or something like that) in the manual.


    The Sony A100 has a manual flash. If you open the flash, it will fire.
    If you close the flash, it won't fire. It won't automatically pop up
    when it is dark. In dim light, if I close the flash, the camera will
    focus without flash-assist (doesn't focus very well, actually). If I
    open the flash, it will focus with flash-assist and the flash will fire
    during the picture.
    jeffrey, Dec 24, 2006
    #10
  11. jeffrey

    Bill Tuthill Guest

    jeffrey <> wrote:
    >
    >> I wouldn't recommend this function, which would be called "Shot Priority"
    >> instead of "Focus Priority" in the manual.

    >
    > Where can I find this function? I can't find it in my manual, but I'd
    > like to try it out.


    The information I found says the Sony A100 does not have custom functions,
    and this is something that Minolta would have controlled that way.
    This is a huge disappointment for me, somebody who is a potential market
    for the Sony A100, being a Minolta lens owner.

    > The Sony A100 has a manual flash. If you open the flash, it will fire.
    > If you close the flash, it won't fire. It won't automatically pop up
    > when it is dark. In dim light, if I close the flash, the camera will
    > focus without flash-assist (doesn't focus very well, actually). If I
    > open the flash, it will focus with flash-assist and the flash will fire
    > during the picture.


    What lens do you have? Lens can have a huge impact on autofocus speed.

    The Photozone.de comparison table indicates the A100 has autofocus range
    of -1 to 18 EV, which is relatively good for low-light (-1) autofocusing.
    I tend to think the lens is at fault.
    Bill Tuthill, Dec 25, 2006
    #11
  12. jeffrey

    jeffrey Guest

    Bill Tuthill wrote:
    > The information I found says the Sony A100 does not have custom functions,
    > and this is something that Minolta would have controlled that way.
    > This is a huge disappointment for me, somebody who is a potential market
    > for the Sony A100, being a Minolta lens owner.


    That really sucks.

    > What lens do you have? Lens can have a huge impact on autofocus speed.


    I have the Sony 18-70mm f/3.5-5.6 (comes in the kit) and a Sigma
    70-300mm f/4-5.6 lens. I never use my Sigma lens in low light, though.
    jeffrey, Dec 25, 2006
    #12
  13. jeffrey

    Bill Tuthill Guest

    jeffrey <> wrote:
    >> The information I found says the Sony A100 does not have custom functions.

    > That really sucks.


    Yup. I would have expected the Sony A200 (or something higher end) by now,
    and one would assume that a high-end DSLR would have custom functions.

    >> What lens do you have? Lens can have a huge impact on autofocus speed.

    > I have the Sony 18-70mm f/3.5-5.6 (comes in the kit) and a Sigma
    > 70-300mm f/4-5.6 lens. I never use my Sigma lens in low light, though.


    That is a fairly lousy lens, but reviews of it never mention slow autofocus.
    None of the reviews have complained about the A100's autofocus speed, but
    it appears they always tested using better lenses than the 18-70/3.5-5.6.
    Sorry to hear this.

    My advice is to visit a camera store and try out the Tamron 17-50/2.8 XR
    to see if it improves autofocusing speed. That is probably the best
    general-purpose lens available for the A100.
    Bill Tuthill, Dec 26, 2006
    #13
  14. Bill Tuthill <> wrote:

    > The information I found says the Sony A100 does not have custom functions,
    > and this is something that Minolta would have controlled that way.
    > This is a huge disappointment for me, somebody who is a potential market
    > for the Sony A100, being a Minolta lens owner.


    The Sony DSLR-A100 (alpha) Manual is at:
    http://esupport.sony.com/US/perl/model-documents.pl?mdl=DSLRA100

    On Pages 93 to 97 Under Custom Functions which the custom menus control
    include:

    Focus Priority Setup
    Focus/Depth of Field Hold Button
    AEL Button
    Shutter/Aperture Ctrl Dial Set
    Ambient Light Exposure Compensation Set
    AF Illuminator
    Media Shutter Lock
    Lens Shutter Lock
    AF Area Setup Display
    Automatic/Manual Monitor Display
    Auto Rotate Record Display
    Auto Rotate Play Display

    What custom functions were you looking for?

    --
    Pardon my spam deterrent; send email to
    Cheers, Steve Henning in Reading, PA USA
    http://home.earthlink.net/~rhodyman
    Stephen Henning, Dec 27, 2006
    #14
  15. jeffrey

    Bill Tuthill Guest

    Stephen Henning <> wrote:
    >
    > The Sony DSLR-A100 (alpha) Manual is at:
    > http://esupport.sony.com/US/perl/model-documents.pl?mdl=DSLRA100
    > On Pages 93 to 97 Under Custom Functions
    >
    > Focus Priority Setup
    > Focus/Depth of Field Hold Button
    > AEL Button
    > Shutter/Aperture Ctrl Dial Set
    > Ambient Light Exposure Compensation Set
    > AF Illuminator
    > Media Shutter Lock
    > Lens Shutter Lock
    > AF Area Setup Display
    > Automatic/Manual Monitor Display
    > Auto Rotate Record Display
    > Auto Rotate Play Display
    >
    > What custom functions were you looking for?


    Looks like it would be the first one, Focus Priority,
    switched to Shutter Priority or something like that.

    If Sony uses the Minolta autofocus system, I would also
    disable AF Illuminator.

    Thanks for the info! Sony marketing ought to tell
    dpreview.com, bphotovideo.com, photozone.de
    and all the other sites that fail to mention A100 custom functions.
    Bill Tuthill, Dec 27, 2006
    #15
  16. Bill Tuthill <> wrote:

    > Thanks for the info! Sony marketing ought to tell
    > dpreview.com, bphotovideo.com, photozone.de
    > and all the other sites that fail to mention A100 custom functions.


    It is the other way around. The review sites need to read the manual,
    not just take pictures and make some half-assed comments. Now you know
    the quality of the reviews. Most every camera company posts their
    manuals so we can read them. We don't need to believe what these
    so-called reviewers write.

    --
    Pardon my spam deterrent; send email to
    Cheers, Steve Henning in Reading, PA USA
    http://home.earthlink.net/~rhodyman
    Stephen Henning, Dec 27, 2006
    #16
  17. jeffrey

    jeffrey Guest

    Bill Tuthill wrote:
    > If Sony uses the Minolta autofocus system, I would also
    > disable AF Illuminator.


    Will it focus better without the AF-light?
    jeffrey, Dec 29, 2006
    #17
  18. jeffrey

    Bill Tuthill Guest

    jeffrey <> wrote:
    >
    >> If Sony uses the Minolta autofocus system, I would also
    >> disable AF Illuminator.

    >
    > Will it focus better without the AF-light?


    My Minolta SLR does. It makes a huge difference.

    With AF-Illuminator enabled, as it is by default, the AF system hunts,
    turning the lens back and forth for up to a minute.

    With AF-Illuminator disabled by custom function, the AF system can focus
    in extremely low light, e.g. inside a theater with lights dimmed.
    Bill Tuthill, Jan 2, 2007
    #18
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