Internal ND filters on the XH-A1 affecting focus

Discussion in 'Professional Video Production' started by Jacques E. Bouchard, Jul 30, 2008.

  1. I've had the camera for a few months, but that was the first time I shot
    footage fully zoomed-in with an ND filter.

    I went back to the mountain last week and shot more footage of the same
    cityscape as the first time. I very carefully adjusted the focus to make
    sure I noticed every small change. I still couldn't bring a building
    3,000 feet away into focus when using the ND filter. I thought maybe it
    was my eyes getting tired, but a photographer friend who reviewed the
    footage said the same thing: "Why is it out of focus?".

    At this point I'm assuming it's just a shortcoming of the lens, which
    wasn't meant to give perfect results at such great distances.


    jaybee
     
    Jacques E. Bouchard, Aug 25, 2008
    #61
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  2. Or switch the ND filter out? All three of these conditions
    (plus adding a front filter, making 6...) should give the same
    result (soft or sharp) depending on whether the built-in ND
    filter is flat or not or the lens/body is defective or not. If results
    are sharper with the ND filter switched out, then that has the
    problem. If the image is equally (and unacceptably) unsharp
    with all of the conditions above, then the lens is defective or
    the body mount spacing is incorrect. Use logic and simple
    tests to determine the source of the problem...
    --David Ruether
     
    David Ruether, Aug 25, 2008
    #62
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  3.  
    David Ruether, Aug 25, 2008
    #63
  4. Yes but that's irrelevant - I was focusing visually, not by distance
    reading.
    Manually. I even tried pushing the AF button, but at that distance I
    don't know if it would focus accurately.
    It's default, as I did not change it. But I was turning it in very small
    increments.
    Using the viewfinder, as I find the LCD screen to be too unreliable
    (especially in bright sunlight). I tried pointing to a billboard at about
    the same distance and focused without the ND until I could read it. I
    could not with the ND engaged.
    9.5/f without, 6.2/f with. It was a very bright day. I could try again by
    leaving the aperture constant and changing the shutter speed.
    I have to go back to the mountain some time this week or next (last week
    was too hazy, the footage was no good). I'll do another test then and
    post the results.

    I have to say that at any setting other than fully zoomed-in on a distant
    subject, I have no problem focusing. Even at SD, the camera yields
    gorgeous pictures.


    jaybee
     
    Jacques E. Bouchard, Aug 25, 2008
    #64
  5. Jacques E. Bouchard

    Larry in AZ Guest

    He said that weeks ago, when this first began.
     
    Larry in AZ, Aug 25, 2008
    #65
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