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Thread: Focus Issues

  1. #21
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    If you bought say, a Minolta AF 200 F2.8 G APO HS 20 years ago, it is probably still working pretty good.
    Lenses are now more complex with electronics built in and maybe a lens motor. Personally I'd like to see Sony stick with the in body motor to keep lens complexity to a minimum but I doubt they'll listen.
    The premium priced lenses should carry a 5 year warranty.

  2. #22
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    Quote Originally Posted by dr4gon View Post
    ......People on their A900's have been adjusting the CZ 16-35mm to get better corner sharpness (don't quite understand exactly, but the way the lens is tuned, it's sort of an average of all points, or something or another)....
    Haven't seen that dr4gon, do you remember where you saw it?
    If they're trading off centre sharpness for edge sharpness from a flat target I'm not sure that's a good idea especially if it's at the wide end where field curavature is most pronounced.
    Currently Chuck Westfall of Canon says (of microfocussing) "we should pick the one focal length of the zoom we use most often", presumably at the expense of the others.

    On the focus issue I found this page and chart by Jeffrey Friedl ... http://regex.info/blog/photo-tech/focus-chart ... the page makes for interesting reading if you're having AF problems and the chart looks to be an advancement over the Tim Jackson chart.

    I also found this comment by Canon's Chuck Westfall ...
    "Do not attempt to autofocus on an angled chart, because doing so will degrade the consistency of the camera's focusing measurement. Keep in mind that the camera's AF sensor is comprised of multiple pairs of linear pixel arrays. If you attempt to autofocus on a single line in an angled focusing chart, only a few pixels from each active pixel array will "see" the target. Ideally, the contrast in the reference target should cover the entire area of the camera's center focusing point, and the reference target should be perfectly parallel to the camera's focal plane."

    You could go for the LensAlign device (review here... http://www.luminous-landscape.com/re...ensalign.shtml ...) but it's costly and of course, it still doesn't tell you whether it's the Lens or Camera that's out of whack.

  3. #23
    Join Date
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    Took some searching but here we are:

    -/+ 2 gave the best sharpness for one person

    http://forums.dpreview.com/forums/re...27&q=1635&qf=m

    http://forums.dpreview.com/forums/re...ssage=30979253

    These would be the benefits I had in mind. On the fly, slight adjustments.
    flickr

    Canon 7D - 5D | 550EX - 430EX II - (2) PW FlexTT5 | 24-105 f4L | 70-200 f2.8L IS | 100 f2.8L IS | 50 f1.8 II

  4. #24
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    Thanks for that link. No such thing as a perfect Zoom, but it's still sounds like a great lens.

  5. #25
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    I guess if you wanted a better image, well with any lens, you could bracket focus and merge them together
    flickr

    Canon 7D - 5D | 550EX - 430EX II - (2) PW FlexTT5 | 24-105 f4L | 70-200 f2.8L IS | 100 f2.8L IS | 50 f1.8 II

  6. #26
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    How do you bracket focus? Can it be done on the A100. I was trying an image stacker program yesterday with my ladybug image. I didn't work because the images were notg taken with a tripod.

    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/

  7. #27
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    Not easily Frank, and you need a tripod, a cooperative subject and manual focus.
    The macro boys call it "focus stacking".
    I don't think the Ladybird is going to be easy with your Tamron and 1:2 magnification. Practice on something a bit bigger like a frog, a flower or a kids toy.

  8. #28
    Join Date
    Dec 2007
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    Thanks I will give it a try.
    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/

  9. #29
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    Quote Originally Posted by sparkie1263 View Post
    How do you bracket focus? Can it be done on the A100. I was trying an image stacker program yesterday with my ladybug image. I didn't work because the images were not taken with a tripod.

    Frank
    no camera i know of focus brackets although i think it would be a handy feature to have.
    D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75
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  10. #30
    Join Date
    Dec 2007
    Posts
    2,562
    Thanks Rooz
    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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