Shooting moving subject (walking) at f/1.8 - poor hit rate in indoor light

Started Dec 18, 2012 | Discussions thread
MOD TOF guy Forum Pro • Posts: 13,497
Re: I have a poor hit rate with a still subject as well (example)

I hate doing microadjustment on lenses, as I find I can't do it accurately....

I assure you that it's easy to do. Here are Nikon's explanations . Here is a slightly different way:

  • AFS of course, using the central AF sensor, focus priority (in principle)
  • Target: print "+" on a white page. You can print several of different size on one page, each one separated by the others with some space: I prefer the size of this sign to be as large as the area covered by the sensor but not larger.
  • Tape target on a wall. It must be reasonably well lit.
  • Put camera on tripod or if you don't have one set the camera on a table. Depending on the lens weight: you may need to put something under a heavy lens to prevent the camera - lens combo from pointing down. If you use a small target (as suggested here) there is no need to go crazy about how parallel the sensor plane must be compared to the target. Parallel by sight is good enough.
  • Use MLU and a remote. If no remote use the delayed actuation (I'm aware that I'm probably giving more details than you need, just being thorough).
  • Take a shot using manual focus and LV at larger magnification. This serves as a reference: the final image must be as good. This is a tremendous help in getting it right.
  • For zoom (not the case here) either set focal length at mid-value or at the value you use most often
  • It looks like your lens slightly front focuses, in which case you need a negative value. But to be sure I'd ignore this, just in case something peculiar happened with the specific image you posted (YMMV if you have several pictures with all consistent front focusing)
  • Move lens AF ring to infinity. Focus. Release shutter. Re-focus and fully depressed the shutter twice to move the mirror up and take the shot (again: trying to be thorough in the description - most of it is probably of no use to you).
    Note that the double-focus action is not necessary but something I do to improve reliability of the results
  • Move lens AF ring to closest focusing distance and repeat to get another picture.
  • Set fine tuning to -10 repeat the above, then -20, then 10 20. Bring to computer at 100% magnification (remember you can resize the windows size to see only the "+"). It should be obvious that 2 of them are sharper than the others, and they will be pictures taken at consecutive tested micro-adjustements settings. In your case from the picture you post (small front focusing) it would be be 0 and -10.
  • Then repeat the procedure half way in the range defined by the 2 best corrections (-5, half way between 0 and -10, in the example above). Again compare and you should be able to decide which range is best. Say 0 and -5. Take images at all intermediary steps -1 -2 -3 -4. And make the call. I don't find it always easy to decide between 2 consecutive values, in which case I pick the lowest correction (for no good reason really). But I guarantee you that if you hesitate between -4 and -5 using -4 will already bring a noticeable improvement compared to the default, 0.

A bit of time to do but worth it considering your investment in camera and lens.

Good luck!

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Thierry - posted as regular forum member

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