AF sensor size check - quick setup

Discussion in 'General Technical Discussion' started by Iliah, Sep 16, 2005.

  1. Iliah

    Iliah

    Jan 29, 2005
    nowhere
  2. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  3. Iliah

    Iliah

    Jan 29, 2005
    nowhere
    Dear Paul,


    Some advantages I see :)
    Grid of notebook screen is a good target to confuse AF - so, it focuses on the sharp contrasty line - or fails to focus.
    It is easy to check lines going in different directions, including diagonal.
    You can make the line very thin.
    You can overlay the captures in PS easily, as the background is pretty even and keys off in a snap.

    I have 2 D2X cameras, they have different zones of AF sensors sensitivity.
     
  4. TOF guy

    TOF guy

    208
    Mar 11, 2005
    Hi Iliah,

    You're way too concise. People like me needs you to slow down :redface: !

    Just to make sure I understand the setup :confused: !

    You computer screen displays a white page, with just a black vertical line in the middle. The room is relatively dark, which I suppose avoid any light distraction other than the monitor screen (or maybe it does not matter: the room is dark because that is the way it should be, i.e. it allows to use the monitor with a darker black point, increasing monitor DR)

    Then you select AFS-S, the central AF sensor (say), and take a series of pictures. One differs from the next one as follow: the camera points to a slightly different horizontal position. At some point, the black line comes outside out the AF sensor area, and focus fails (the black line becomes blurry in the pics).

    Of course, to map the sensor horizontally, you'd need to display an horizontal line, and sweep vertically. And you can test how the sensor tracks with diagonal lines, etc.

    I think I've got it ! Just needed to lay it down for myself :smile: !

    Thierry
     
  5. Iliah

    Iliah

    Jan 29, 2005
    nowhere
    Dear Thierry,

    In reality I use longer lens setting, to fill the frame with the screen for the most distant sensor positions. It is easier to overlay images that way.

    The line is thinner, too.

    Tripod is equipped with geared head, Manfrotto 410 for the case.

    Camera is in Focus priority. I start far from sensor, and rotate the head pressing release (MC-20) until camera takes a shot. Then I pass the sensor and start rotating the camera in the opposite direction. I switch sensors using Nikon Camera Control.

    I use Slim Keyboard ViewSonic KU 201, which has 2 USB ports - I plug the camera into one port, and mouse into another. Keyboard cord is long enough to make the whole setup convinient.
     
    Last edited by a moderator: Sep 17, 2005
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