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Thread: Lens Test

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

    Lens Test

    I tried the back focus test on two of my lenses. I don't know if I did it right. What do you think??

    Thanks Frank

    Minolta 50mm



    Camera Make: SONY
    Camera Model: DSLR-A100
    Image Date: 2008:12:27 23:51:12
    Flash Used: No
    Focal Length: 100.0mm (35mm equivalent: 150mm)
    Exposure Time: 0.200 s (1/5)
    Aperture: f/4.0
    ISO equiv: 400
    White Balance: Auto
    Metering Mode: Spot
    Exposure: aperture priority (semi-auto)



    Tamron 70-300



    Camera Make: SONY
    Camera Model: DSLR-A100
    Image Date: 2008:12:27 23:48:31
    Flash Used: No
    Focal Length: 50.0mm (35mm equivalent: 75mm)
    Exposure Time: 0.200 s (1/5)
    Aperture: f/4.0
    ISO equiv: 400
    White Balance: Auto
    Metering Mode: Spot
    Exposure: aperture priority (semi-auto)
    Last edited by sparkie1263; 12-27-2008 at 08:25 PM.
    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
    Feb 2006
    Location
    Des Plaines, IL
    Posts
    9,560

    Cool Into your positions ...

    Frank ... they look a little close ... spread them about an inch apart, horizontal ... and an inch and a half in between, diagonally.

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    Last edited by DonSchap; 12-27-2008 at 08:43 PM.
    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

  3. #3
    Join Date
    Dec 2007
    Posts
    2,562
    I though it was an inch apart. I forgot my Ginkoba.LOL I will do it again in the morning.

    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
    You want a bit of space between each battery ... so the camera is not tricked into focusing incorrectly, but on the center battery ONLY.

    Use spot focus and your WIDEST aperture.
    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
    I am going to make a index card so I have it made and don't have to rely on my memory.

    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/

  6. #6
    Join Date
    Nov 2008
    Location
    Monmouthshire, UK
    Posts
    2,152
    You might find this helpful http://focustestchart.com/chart.html Just print out the test chart and take a picture. The test was designed for Canon back focus issues but it works for any camera.

    You can see that on this test the lens is in focus from about 9mm in front to about 18mm behind. This is normal, I usually work on DOF being one third in front and two thirds behind the focus point.

    Somebody on this forum originally pointed this test out and I'd give credit if only I could remember who.
    Attached Images Attached Images  

  7. #7
    Join Date
    Dec 2007
    Posts
    2,562
    I did test my other lenses with that test. I just wanted to do a quick test of the Minolta 50 mm.
    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/

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