D200 AF sensor alignment with focus brackets

Discussion in 'Nikon' started by tom_luongo|1, Aug 1, 2006.

  1. How closely should the AF sensors align with the focus brackets in the
    viewfinder?

    My D200 seems to be off by about 1/2 a bracket width. The AF sensors seem
    shifted to the left by that amount. In single sensor mode, the camera locks
    noticeably more easily when the focus target is to the left of the bracket
    versus to the right of the bracket. (Or below the bracket instead of above the
    bracket when holding the camera vertically)

    I think this partly explains why I sometimes had trouble getting the AF to lock
    on eyes when I shot portraits. I'd been placing the bracket on the subject's
    eyes but I suspect the actual AF sensor was below the eye on the cheek. It
    will be kind of annoying to compensate like this if Nikon is unable to adjust
    this.

    I haven't had the chance to try the compensation in the real world yet, but it
    seems like it will work based on tests I did with a black dot drawn on the wall.

    Of course, I could be completely off the mark and blaming the camera for
    something that is really user error.

    Thanks for your feedback.
     
  2. Tom I think a single black dot is a bad taget for testing AF if you are not just testing focus on the dot itself. Nearby (to the real lower contrast target) objects of high contrast can influence AF. I suggest you use something else like random objects in random arrangment. Just a thought .-)
     
  3. The sensors can certainly be out of alignment with the brackets on the view screen. I know that the sensor areas are bigger than the areas marked. The best way to check alignment is to moun the camera on a tripod and then move a target around the maked sensor area and see when the camera focuses. The best target is a thick black line on a white background, with the line oriented 90� to the direction of the sensor. You want a target that the AF system will work best on, because you are checking the sensor alignment and not the AF performance.
     
  4. http://www.nikonians.org/nikon/d2x_sensor_size/ was the original article that I saw that alerted me to this.
    I understand that the AF sensors work best on lines. But the black dot actually works pretty well for me too.
    This is something that really needs a picture. I'll try to do that later. Words failed me when I was tried to describe what I was doing.
    The big question is whether the AF sensors should be centered on the focus brackets. Or is it normal for them not to align precisely? And if they don't align, how much is normal?
     
  5. The AF system in the D200 is not the same as in the D2x; in fact they work very differently.

    I just wasted almost an hour writing a reply to this, hit the "submit" button, and....poof, it's gone! Man, that sucks.

    Trying to decide whether or not to take the time to re-write.
     
  6. People seem to nickpit too much about AF systems. I never had AF problems with neither the D200 nor the F70.

    My only complaints would be the slow speed with non-AFS lenses and the somewhat poor performance on low light.

    Other than that, AF seems to be fine and precise with the D200, even shooting with large apertures.

    Good luck
     
  7. Jeffrey, thanks for taking the time to write, even if "submit" lost it. I've been burnt once or twice myself. I spent twenty minutes trying to describe the behavior and decided I really needed to make a picture instead, but unfortunately won't have the time for a bit.

    I know that the D2X has a different autofocus system. Bruce had a pretty concise above of the testing method.

    I'm convinced my sensors lay a bit to the left of the focus brackets. I don't really know yet if it matters, as it's an easy enough thing to compensate for. But I have been having the experience of having trouble focusing on eyes when holding the camera in portrait mode.

    Nikon tells me that it doesn't matter if the AF sensors don't line up with the AF brackets and that the alignment is set at the factory and can't be adjusted. I think that's sloppy for a $1700 camera but I agree I might be nitpicking too.
     
  8. I just noticed some similar "issues" with my D1. Obviously, this is nothing to worry about and I was being nitpicky, but it's still a good thing to know about.
     

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