newbie with focusing issue

Discussion in 'Photography Beginners' Forum' started by tripwater, Oct 12, 2009.

  1. tripwater

    tripwater TPF Noob!

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    Hello,

    I am noticing a consistent issue with my focusing when using my macro lens. I know things are much more touchy doing close up stuff but I am not getting sharp results in AF mode or in manual. The lens I am using is the Tamron 90mm macro which I have gotten great results with but I think the inconsistency is all on my part.

    A perfect example is this morning it is raining out and I saw this web in the grass with droplets in it. I have the camera set to only have single point focusing in the center. All pictures were at f32. I am kind of at a loss here. Even when the camera's AF said it was sharp the images are dull. The camera is my roommate's Canon 20D and mounted on a tripod. My camera should be in today :)

    Any help or ideas would be great! I would like to figure out what I am doing wrong so I can fix it. Thanks


    These images look a a bit more sharp at this size but full size cr2 are just worthless in my opinion.

    here are 2 shots in MF mode and through the view finder, it looked sharp!
    [​IMG]

    [​IMG]




    AF mode
    [​IMG]


    [​IMG]
     
  2. JamesMason

    JamesMason TPF Noob!

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    Are you pressing the shutter by hand ?
     
  3. tripwater

    tripwater TPF Noob!

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    no, using a cable release. I wonder if I needed to lock the mirror up for these shots? I have heard about macro shooters having to do that in some cases to reduce vibrations...
     
  4. KmH

    KmH Helping photographers learn to fish Supporting Member

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    Use every trick there is. Mirror lockup, remote release, rock steady tripod/head. A rail focuser helps a great deal.
     
  5. ErectedGryphon

    ErectedGryphon TPF Noob!

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    I would definately try the mirror lock up, but also open up the lens more. F32 might be causing too long an exposure, and a slight breaze could be moving the subject causing the blur.
     
  6. Derrel

    Derrel Mr. Rain Cloud

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    The last image shows that the depth of field band is pretty limited--the left side is slightly out of he band of best focus, the upper right hand corner is within the band of sharpest focus.

    These are not "that" bad looking. The spider webs are rendered as single lines. I have seen much,much worse. One issue though is that the Tamron 90 is not at its best at f/32--that small aperture is beyond optimum,and some amount of image softening from diffraction will occur at f/32, plus f/32 puts your shutter speeds into a dangerously slow range where even the slightest movement from wind, or your own body moving, can move tiny subjects. Plus, the slow speeds necessitated by f/32 mean the shutter speeds are slow, which can cause mirror slap on the way up, then the first shutter curtain slams open, the exposure is made...and the vibration from the mirror going up and then the shutter opening can be enough on high-magnification work like this to cause softness issues.

    Your focusing is not really that bad--it looks like good focusing to me.
     
  7. chip

    chip TPF Noob!

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    using an IS lens should help too. Canon just released a 100mm f2.8 marco with IS.
     

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