EOS AF lens that doesn't AF

Discussion in 'Digital Photography' started by eug k, Apr 5, 2004.

  1. eug k

    eug k Guest

    hi,

    I sold a 28-105mm f3.5 lens recently, and the buyer says it
    doesn't autofocus.

    In his words:

    "I used the lens this weekend to take pictures from a
    performance. It appears that the camera works well with
    short distances, but when the object is at a a distance
    of more than 15 meters the automatic focussing keeps
    going in and out , it does not find a proper position. This
    I think is a malfuction from the lens.The macro also palys up."


    I further clarified that he can get a good focus if he focuses
    manually. In AF mode, the lens just seeks from end to end.
    Isn't AF handled by the camera and not the lens, searching
    for best contrast? It's an EOS300D.


    thanks



    --
     
    eug k, Apr 5, 2004
    #1
    1. Advertising

  2. > "I used the lens this weekend to take pictures from a
    > performance. It appears that the camera works well with
    > short distances, but when the object is at a a distance
    > of more than 15 meters the automatic focussing keeps
    > going in and out , it does not find a proper position. This
    > I think is a malfuction from the lens.The macro also palys up."


    What kind of performance. Nobody's autofocus works well in low light
    conditions.
     
    Randall Ainsworth, Apr 5, 2004
    #2
    1. Advertising

  3. eug k

    cole Guest

    Well I don't know how a macro can "play up" - that's just a close focusing
    distance
     
    cole, Apr 5, 2004
    #3
  4. eug k

    Dave Guest

    I have the Digital Rebel (300D) and I experience was he described
    with every lens that I use if there isn't enough available light. I would
    suggest that the auto focus be tested in a situation with plenty of light.
    i.e.@ ISO 100 & F8, shutter speed would be faster then 1/60th.
    -Dave

    "eug k" <> wrote in message
    news:c4sjoh$p6k$...
    >
    > hi,
    >
    > I sold a 28-105mm f3.5 lens recently, and the buyer says it
    > doesn't autofocus.
    >
    > In his words:
    >
    > "I used the lens this weekend to take pictures from a
    > performance. It appears that the camera works well with
    > short distances, but when the object is at a a distance
    > of more than 15 meters the automatic focussing keeps
    > going in and out , it does not find a proper position. This
    > I think is a malfuction from the lens.The macro also palys up."
    >
    >
    > I further clarified that he can get a good focus if he focuses
    > manually. In AF mode, the lens just seeks from end to end.
    > Isn't AF handled by the camera and not the lens, searching
    > for best contrast? It's an EOS300D.
    >
    >
    > thanks
    >
    >
    >
    > --
    >
     
    Dave, Apr 5, 2004
    #4
  5. eug k

    [BnH] Guest

    Eugene,

    It does happen.
    Last time I bought a used Nikkor 24-85 f/ 2.8-4, it does not want to focus
    in 3 of my bodies.
    Somehow the problem it does not focus @ infinity .. the focus always runs.
    There is a fix for it .. but might be costly [CLA-ing them for quick fix]
    Too bad it has a dent in the filter thread, if not I dun mind sending it to
    maxwell to be fixed.
    Hell it was a sharp lens :(

    =bob=




    "eug k" <> wrote in message
    news:c4sjoh$p6k$...
    >
    > hi,
    >
    > I sold a 28-105mm f3.5 lens recently, and the buyer says it
    > doesn't autofocus.
    >
    > In his words:
    >
    > "I used the lens this weekend to take pictures from a
    > performance. It appears that the camera works well with
    > short distances, but when the object is at a a distance
    > of more than 15 meters the automatic focussing keeps
    > going in and out , it does not find a proper position. This
    > I think is a malfuction from the lens.The macro also palys up."
    >
    >
    > I further clarified that he can get a good focus if he focuses
    > manually. In AF mode, the lens just seeks from end to end.
    > Isn't AF handled by the camera and not the lens, searching
    > for best contrast? It's an EOS300D.
    >
    >
    > thanks
    >
    >
    >
    > --
    >
     
    [BnH], Apr 6, 2004
    #5
  6. eug k

    Quaoar Guest

    eug k wrote:
    > hi,
    >
    > I sold a 28-105mm f3.5 lens recently, and the buyer says it
    > doesn't autofocus.
    >
    > In his words:
    >
    > "I used the lens this weekend to take pictures from a
    > performance. It appears that the camera works well with
    > short distances, but when the object is at a a distance
    > of more than 15 meters the automatic focussing keeps
    > going in and out , it does not find a proper position. This
    > I think is a malfuction from the lens.The macro also palys up."
    >
    >
    > I further clarified that he can get a good focus if he focuses
    > manually. In AF mode, the lens just seeks from end to end.
    > Isn't AF handled by the camera and not the lens, searching
    > for best contrast? It's an EOS300D.
    >
    >
    > thanks


    It is the camera that handles the control and evaluation of the
    autofocus and drives the lens. EOS lenses have never been reliable
    focusing in low light, against textures with little direct reflectivity
    such as cat and dog fur, some tree leaves, etc. With low light or low
    reflectivity, the change in the control point is flat and the control
    algorith fails to converge and the lens hunts. Canon has not hidden
    these characteristics of the lenses; every user manual I have (not
    anything recent) discusses the limitations. IMO, it is not a defect
    since manual focus is a viable alternative. The auto/manual focus
    switch becomes an element of using the lenses after even a little use.

    Your customer should give the lens a real workout; it costs nothing but
    time to test focus against a variety of targets in different lighting.
    Again, the EOS control algorithm is built into the camera; inability to
    focus is a camera problem unless the lens is broken, which should be
    readily obvious if it is.

    Q
     
    Quaoar, Apr 6, 2004
    #6
  7. eug k

    jean Guest

    Also, if you let the camera decide which focus point to use it will be more
    "confused" in low light situations. Tell him to select only the center AF
    point, it shoud focus much better and faster.

    Jean

    "Quaoar" <> a écrit dans le message de
    news:...
    > eug k wrote:
    > > hi,
    > >
    > > I sold a 28-105mm f3.5 lens recently, and the buyer says it
    > > doesn't autofocus.
    > >
    > > In his words:
    > >
    > > "I used the lens this weekend to take pictures from a
    > > performance. It appears that the camera works well with
    > > short distances, but when the object is at a a distance
    > > of more than 15 meters the automatic focussing keeps
    > > going in and out , it does not find a proper position. This
    > > I think is a malfuction from the lens.The macro also palys up."
    > >
    > >
    > > I further clarified that he can get a good focus if he focuses
    > > manually. In AF mode, the lens just seeks from end to end.
    > > Isn't AF handled by the camera and not the lens, searching
    > > for best contrast? It's an EOS300D.
    > >
    > >
    > > thanks

    >
    > It is the camera that handles the control and evaluation of the
    > autofocus and drives the lens. EOS lenses have never been reliable
    > focusing in low light, against textures with little direct reflectivity
    > such as cat and dog fur, some tree leaves, etc. With low light or low
    > reflectivity, the change in the control point is flat and the control
    > algorith fails to converge and the lens hunts. Canon has not hidden
    > these characteristics of the lenses; every user manual I have (not
    > anything recent) discusses the limitations. IMO, it is not a defect
    > since manual focus is a viable alternative. The auto/manual focus
    > switch becomes an element of using the lenses after even a little use.
    >
    > Your customer should give the lens a real workout; it costs nothing but
    > time to test focus against a variety of targets in different lighting.
    > Again, the EOS control algorithm is built into the camera; inability to
    > focus is a camera problem unless the lens is broken, which should be
    > readily obvious if it is.
    >
    > Q
    >
    >
     
    jean, Apr 6, 2004
    #7
  8. eug k

    Cello Guest

    Have your buyer change his settings to a single focus point. This made all
    the difference for me on my 300D when shooting in low-light conditions.


    "eug k" <> wrote in message
    news:c4sjoh$p6k$...
    >
    > hi,
    >
    > I sold a 28-105mm f3.5 lens recently, and the buyer says it
    > doesn't autofocus.
    >
    > In his words:
    >
    > "I used the lens this weekend to take pictures from a
    > performance. It appears that the camera works well with
    > short distances, but when the object is at a a distance
    > of more than 15 meters the automatic focussing keeps
    > going in and out , it does not find a proper position. This
    > I think is a malfuction from the lens.The macro also palys up."
    >
    >
    > I further clarified that he can get a good focus if he focuses
    > manually. In AF mode, the lens just seeks from end to end.
    > Isn't AF handled by the camera and not the lens, searching
    > for best contrast? It's an EOS300D.
    >
    >
    > thanks
    >
    >
    >
    > --
    >
     
    Cello, Apr 6, 2004
    #8
  9. eug k

    Paul J Gans Guest

    In rec.photo.digital Dave <> wrote:
    >I have the Digital Rebel (300D) and I experience was he described
    >with every lens that I use if there isn't enough available light. I would
    >suggest that the auto focus be tested in a situation with plenty of light.
    >i.e.@ ISO 100 & F8, shutter speed would be faster then 1/60th.
    >-Dave


    The ability to manually focus in such situations is one of the
    reasons for buying a camera such as the 300D.

    ---- Paul J. Gans
     
    Paul J Gans, Apr 8, 2004
    #9
  10. eug k

    John Navas Guest

    [POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]

    In <c53j0i$r66$> on Thu, 8 Apr 2004 13:10:42 +0000 (UTC),
    Paul J Gans <> wrote:

    >In rec.photo.digital Dave <> wrote:
    >>I have the Digital Rebel (300D) and I experience was he described
    >>with every lens that I use if there isn't enough available light. I would
    >>suggest that the auto focus be tested in a situation with plenty of light.
    >>i.e.@ ISO 100 & F8, shutter speed would be faster then 1/60th.

    >
    >The ability to manually focus in such situations is one of the
    >reasons for buying a camera such as the 300D.


    Lots of lesser cameras can be manually focused.

    --
    Best regards,
    John Navas
    [PLEASE NOTE: Ads belong *only* in rec.photo.marketplace.digital, as per
    <http://bobatkins.photo.net/info/charter.htm> <http://rpdfaq.50megs.com/>]
     
    John Navas, Apr 8, 2004
    #10
  11. eug k

    HooDooWitch Guest

    "Cello" <> somehow managed to post:

    >Have your buyer change his settings to a single focus point. This made all
    >the difference for me on my 300D when shooting in low-light conditions.


    Wot Cello and Jean say. Single point helps.

    --
    HooDooWitch

    "Season to taste."
     
    HooDooWitch, Apr 8, 2004
    #11
  12. eug k

    Paul J Gans Guest

    In rec.photo.digital John Navas <> wrote:
    >[POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]


    >In <c53j0i$r66$> on Thu, 8 Apr 2004 13:10:42 +0000 (UTC),
    >Paul J Gans <> wrote:


    >>In rec.photo.digital Dave <> wrote:
    >>>I have the Digital Rebel (300D) and I experience was he described
    >>>with every lens that I use if there isn't enough available light. I would
    >>>suggest that the auto focus be tested in a situation with plenty of light.
    >>>i.e.@ ISO 100 & F8, shutter speed would be faster then 1/60th.

    >>
    >>The ability to manually focus in such situations is one of the
    >>reasons for buying a camera such as the 300D.


    >Lots of lesser cameras can be manually focused.


    But not as easily. One has to use the display screen
    to see what is going on and that is not nearly as
    satisfactory as through-the-lens focussing.

    Put more directly, it is very hard to get sharp focus
    from the preview screen.

    ---- Paul J. Gans
     
    Paul J Gans, Apr 8, 2004
    #12
  13. eug k

    John Navas Guest

    [POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]

    In <c5469b$5jc$> on Thu, 8 Apr 2004 18:39:39 +0000 (UTC),
    Paul J Gans <> wrote:

    >In rec.photo.digital John Navas <> wrote:
    >
    >>In <c53j0i$r66$> on Thu, 8 Apr 2004 13:10:42 +0000 (UTC),
    >>Paul J Gans <> wrote:


    >>>The ability to manually focus in such situations is one of the
    >>>reasons for buying a camera such as the 300D.

    >
    >>Lots of lesser cameras can be manually focused.

    >
    >But not as easily. One has to use the display screen
    >to see what is going on and that is not nearly as
    >satisfactory as through-the-lens focussing.
    >
    >Put more directly, it is very hard to get sharp focus
    >from the preview screen.


    Again, that depends on the camera. For example, the Sony CyberShot DSC-V1,
    with a street price of about $400, has manual focus-by-wire and good manual
    focus assists.

    --
    Best regards,
    John Navas
    [PLEASE NOTE: Ads belong *only* in rec.photo.marketplace.digital, as per
    <http://bobatkins.photo.net/info/charter.htm> <http://rpdfaq.50megs.com/>]
     
    John Navas, Apr 8, 2004
    #13
  14. eug k

    eug k Guest

    hi guys,

    thanks for all the followups, I forwarded them to the
    buyer and he said he'll try them out. Haven't heard
    back from him since. :)



    In aus.photo eug k <> wrote:
    >
    > hi,
    >
    > I sold a 28-105mm f3.5 lens recently, and the buyer says it
    > doesn't autofocus.
    >
    > In his words:
    >
    > "I used the lens this weekend to take pictures from a
    > performance. It appears that the camera works well with
    > short distances, but when the object is at a a distance
    > of more than 15 meters the automatic focussing keeps
    > going in and out , it does not find a proper position. This
    > I think is a malfuction from the lens.The macro also palys up."
    >
    >
    > I further clarified that he can get a good focus if he focuses
    > manually. In AF mode, the lens just seeks from end to end.
    > Isn't AF handled by the camera and not the lens, searching
    > for best contrast? It's an EOS300D.
    >
    >
    > thanks
    >
    >
    >


    --
     
    eug k, May 3, 2004
    #14
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