AF Fine Tune - how much is too much?

Discussion in 'Nikon' started by simon_hickie|1, Jun 28, 2013.

  1. I've just taken delivery of a new (to me) D7000 (1 year guarantee from Grays of Westminster). I have two lenses: 18-70mm f3.5-4.5 and a Tamron 90mm f2.8 macro. The former needs -10 and the latter about -18 to give a sharp image at the focusing point. Is this too much, in the sense that another lens may need > -20? I might add an f2.8 telezoom at some point, but not in the immediate future so may find out too late that the body needs adjusting.
     
  2. I find I need almost the whole range from
    +15 to -20 with my D800 to cover the
    lenses I have. I wouldn't worry about it
    until you get a lens which falls out of the
    fine tune range. Then take them to
    service.
     
  3. Agreed. If it doesn't fall within the -20 to +20 range, either the lens or the camera needs service.
    Be sure to base your adjustments on an average of multiple measurements.
     
  4. Thanks chaps. I've done a bit more testing and both lenses are settling down at -10, so well within the adjustable range. Things are much simpler with my Olympus OM-D (no mirror!) but Olympus TTL flash leaves a lot to be desired - very obvious pre-flash with subjects often blinking plus obvious delay too.
     
  5. When I receive my 24-70/2,8G, the lens needs -15 to achieve ACCEPTABLE results... After 1 year the zoom rubber became loose , so, I send the lens to Nikon service , mentioning also the focus problem. They calibrate the lens for free , but I have to pay for the rubber :-(
    btw: my D800 work perfect with all my lenses, but refuse to take even one single clear shot with a 80-400 lens, provided by Nikon at a recent NPS members meeting !?
     
  6. I tend toward the "if it ain't broke, don't fix it". However, a previously owned one may have been tinkered with already, but be conservative in assuming the worst.
    So many variables are involved in accurate focus, after all, than just "fine tuning". You can't do these adjustments hand-held of course, to mention only one potential problem.
     
  7. The fine tune adjustment is also dependent on the focus distance, and may also be dependent on the aperture and color of the light (though the latter two are less clear effects than the distance).
    I think a reasonable approach is to determine the correction at around 30x focal length, and then investigate how the correction varies towards long distances. That's what I do, anyway. I think Nikon should urgently provide users with the means of storing distance dependent fine tune settings for each lens. It should be possible for the camera to determine the distance from the D or G lens, and apply the appropriate correction, interpolating linearly between the ranges.
    Fine tune adjustment in my experience requires considerable care and repetition is an excellent idea; any single focus operation can give quite a large variability in the result, but by making many repetitions, a reasonable estimate of the mean error can be made. Also it is a good idea to have reasonably bright lighting conditions when doing these experiments.
     
  8. Ilkka is right. My new d7100 with kit lens (18-105 vr) needed fine tune of -10 at portrait distances, but if I wanted to shoot farther out, like 30 feet or more the focus became softer than if the fine tune was turned off. My discussion with the dealer was that auto focus fine tune was not ideal for zoom lenses and I tend to agree. Who wants to use a zoom lens that has to be adjusted for each distance? At the dealership we tried a new 80-200 f2.8 at portrait distances and the focus was perfect, so we concluded it was my lens that was misbehaving. The lens is now on its way to Nikon repair.
     
  9. For zooms, I measure the optimal fine tune setting at both end of the zoom range, and then use some kind of an average of the two as the setting I dial in the camera. With the 70-200II, the fine tune I use is -4, and that's a relatively insignificant error. However, with the 24-70 I use -12 and with the 14-24, -13. These latter two are definitely significant and without using fine tune, the sharpness at wide apertures is significantly impaired. I would say that with zooms, you need to measure more data to reach a useful overall fine tune value.
    I double checked the data I have and the range of fine tune settings I have in use for the D800 range from +8 to -19, and -20 is used for long distances on the 105 DC. The +15 value I quoted was incorrect recollection. I don't have any lenses where the correction range is insufficient though some are very close to the limit.
     
  10. This is all really helpful advice. Many thanks to you all. I was indeed wondering about the zoom and focus distance things. Hopefully, there will be some better light tomorrow to run some more tests.
     

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