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  1. #1
    Join Date
    Dec 2007
    Posts
    2,562

    Problem with auto focus

    I was having a problem with my 70-300 locking on focus. I did not test my other lenses yet. It keeps searching and stops way out of focus but if I just tap the shutter release button it locks dead on. The only change I made was I added a CLP filter so I took that off and it seems a little bit better.
    Sony A77
    Sony A580
    Sony A 100
    Maxxum 400si.
    Sony 18-70 Kit Lens
    Minolta AF 35-70
    Minolta AF 50 f/1.7
    Tamron 70-300 f/4-5.6 Di LD
    Tamron 60mm Macro
    Tamron 17-50 f/2.8
    Tamron 2x Converter
    Sony HVL-F42AM
    Quantaray 70-300 4.5-5.6 Macro
    Slingshot 200 Bag



    http://www.flickr.com/photos/22083244@N06/

    http://s305.photobucket.com/albums/nn219/sparkie1263/

  2. #2
    Join Date
    Apr 2007
    Location
    Tasmania, Australia
    Posts
    143
    CP filters take about half a stop of light out and this can be enough to slow the AF system on an already slow lens. I have the same issue with my CPL on the Bigma.

  3. #3
    Join Date
    Dec 2007
    Posts
    2,562
    Thats what I was thinking. I don't want to up the iso just to use the filter. I will try it again on a sunny day.( it was real overcast today)
    Thanks Frank
    Sony A77
    Sony A580
    Sony A 100
    Maxxum 400si.
    Sony 18-70 Kit Lens
    Minolta AF 35-70
    Minolta AF 50 f/1.7
    Tamron 70-300 f/4-5.6 Di LD
    Tamron 60mm Macro
    Tamron 17-50 f/2.8
    Tamron 2x Converter
    Sony HVL-F42AM
    Quantaray 70-300 4.5-5.6 Macro
    Slingshot 200 Bag



    http://www.flickr.com/photos/22083244@N06/

    http://s305.photobucket.com/albums/nn219/sparkie1263/

  4. #4
    Join Date
    Feb 2006
    Location
    Des Plaines, IL
    Posts
    9,560
    I thought we had discussed the drawbacks of dark lenses and CPLs ... maybe it was longer ago than I thought. Gee, where does the time go?
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  5. #5
    Join Date
    Dec 2007
    Posts
    2,562
    Don my memory fails me. LOL I do remember you saying that a while back.Time to save some cash and buy some glass. I hate running into all these brick walls. Good thing I did not buy that TC I would br real upset. I would have to shoot only on sunny days or at iso 1600.
    Sony A77
    Sony A580
    Sony A 100
    Maxxum 400si.
    Sony 18-70 Kit Lens
    Minolta AF 35-70
    Minolta AF 50 f/1.7
    Tamron 70-300 f/4-5.6 Di LD
    Tamron 60mm Macro
    Tamron 17-50 f/2.8
    Tamron 2x Converter
    Sony HVL-F42AM
    Quantaray 70-300 4.5-5.6 Macro
    Slingshot 200 Bag



    http://www.flickr.com/photos/22083244@N06/

    http://s305.photobucket.com/albums/nn219/sparkie1263/

  6. #6
    Join Date
    Apr 2007
    Location
    Tasmania, Australia
    Posts
    143
    High ISO still won't make any difference, it is the light coming into the lens that is lost, this slows the AF system. This is all before the light hits the sensor meaning ISO is of no consequence.

  7. #7
    Join Date
    Dec 2007
    Posts
    2,562
    Thanks for explaining that.
    Sony A77
    Sony A580
    Sony A 100
    Maxxum 400si.
    Sony 18-70 Kit Lens
    Minolta AF 35-70
    Minolta AF 50 f/1.7
    Tamron 70-300 f/4-5.6 Di LD
    Tamron 60mm Macro
    Tamron 17-50 f/2.8
    Tamron 2x Converter
    Sony HVL-F42AM
    Quantaray 70-300 4.5-5.6 Macro
    Slingshot 200 Bag



    http://www.flickr.com/photos/22083244@N06/

    http://s305.photobucket.com/albums/nn219/sparkie1263/

  8. #8
    Join Date
    Feb 2006
    Location
    Des Plaines, IL
    Posts
    9,560
    One aspect to the DSLR is they usually do not suffer with fast glass (f/2.8 or better). You can add all the bells and whistles, but when you shoot through consumer glass (f/4 or worse), you do not get much in the way of elbow room for doo-dads.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  9. #9
    Join Date
    Dec 2007
    Posts
    2,562
    Thanks again
    Sony A77
    Sony A580
    Sony A 100
    Maxxum 400si.
    Sony 18-70 Kit Lens
    Minolta AF 35-70
    Minolta AF 50 f/1.7
    Tamron 70-300 f/4-5.6 Di LD
    Tamron 60mm Macro
    Tamron 17-50 f/2.8
    Tamron 2x Converter
    Sony HVL-F42AM
    Quantaray 70-300 4.5-5.6 Macro
    Slingshot 200 Bag



    http://www.flickr.com/photos/22083244@N06/

    http://s305.photobucket.com/albums/nn219/sparkie1263/

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