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Improving D300 Autofocus for BIF

Discussion in 'Nikon DX DSLR Forum' started by tomb18, Jul 10, 2008.

  1. tomb18

    tomb18

    149
    Sep 28, 2007
    Montreal
    Several years ago, I was out shooting some flying owls with my trusty D70 and 70-300 Screw drive lens. On my first day, the number of keepers were around 25%. In otherwords, pretty poor.
    On my way home that day, I bumped in to a Canon user who had at that time, a top of the line Canon camera (don't remember which but it was the 1D something or other) and stopped to talk to him a bit. I told him about the low keeper rate and he mentioned that the higher end cameras have more processing power and were thus able to have better autofocus performance.
    He suggested that I set white balance to a fixed value and not "auto". He also suggested that I set the camera in manual exposure mode. This would be Ok since I was mainly exposing on the bird and once I determined the correct exposure it shouldn't vary as much.
    The next day, I went out and did what he suggested. By the end of the day my keeper rate jumped to over 75%.

    So my question to everyone is have they tried this and do they notice a difference? (I have just started BIF with my D300)
     
  2. I would find that difficult to do. The birds go from sunny sky to over ground or water, which would change things. Like I said I use the bump method and it works great for me, leaving WB to auto and matrix metering and that is with the D300. I would say my keeper rate is around 70%.

    Nancy
     
  3. tomb18

    tomb18

    149
    Sep 28, 2007
    Montreal
    On the other hand, wouldn't the exposure for the bird (for the most part unless he passed in a shadow) remain the same independent of the background? Also the white balance should be very similar and of course changeable if you shoot in raw?
     
  4. I guess maybe so, but your ec would change and I would be trying to tweak a dial for ec - or + or in maual I suppose it would be the increase and decrease exposure, while bumping the AF-ON and trying to track the bird, makes me dizzy just thinking about it. But, I suppose one could get the hang of it with practice. And then again my above mentioned technique works for me, so I can concentrate on the subject. I find the matrix metering, at least on my D300, quite good with Aperture priority.

    Nancy
     
  5. I tried your method for a few minutes this afternoon and found that I could get distant BIFs in focus but wasn't as successful with closer BIFs (however the closer ones had trees in the background). I'm going to keep at it for awhile as it seems promising and it makes sense that AF would be faster if you relieve the CPU of other tasks.

    Thanks for the tip.
     
  6. tomb18

    tomb18

    149
    Sep 28, 2007
    Montreal
    Let us know how it works
     
  7. jfenton

    jfenton

    Jan 26, 2005
    Haverhill, MA
    Are You Talking AF or Exposure

    I'm confused as WB and manual exposure would have absolutely no effect on autofocus.

    The only thing which would be effected would be exposure.
     
  8. Hi Jim

    I agree. But, I think what the starter of this thread was trying to say is that if the camera is not having to work out the WB and exposure, it would have more power or priority to give to the AF. Now, if that is valid, I have not a clue.

    Nancy
     
  9. jfenton

    jfenton

    Jan 26, 2005
    Haverhill, MA
    I Don't Believe It :) 

    I also believe that the image processing and AF processors are two completely seperate entities the way it's been explained to me.

    Perhaps for the first time in the D3 and D300 they are intertwined due to the input of the matrix metering to AF.

    I've certainly never noticed an AF difference between AutoWB and my norm of either UniWB or setting the degrees K myself.
     
  10. tomb18

    tomb18

    149
    Sep 28, 2007
    Montreal
    Jim,
    They may be separate entities but there must still be some signal that informs the shutter circuitry that both the wb and exposure calculations and setting are finished. If no calculations are necessary, then this step should be quicker I would think. Expecially in matrix mode since there is a lookup involved in the calculation. Then again, these functions may be performed much quicker than any autofocus function and thus be insignificant.

    It worked on my D70. Who knows on the D300.
     
  11. This makes since to me, but it is sad that we have to grasp at at staws like this. I guess you would need to turn auto ISO off too. I will give it a try:smile:
     
  12. Holmes

    Holmes

    Oct 28, 2006
    Wyoming, USA
    I really think the issue is contrast related as Jim Fenton has alluded to regarding blue skies and different tonalities. Subject size in the viewfinder certainly has an effect.

    Here's a very fast dog running straight at the camera and I have Auto ISO running, Active D-Lighting, and NR turned on. These settings surely have to be a drain upon computing resources. The camera had no trouble achieving an instant focus lock.

    p570946670-5.png
    Subscribe to see EXIF info for this image (if available)
     
  13. Picture no see. I would be very interested is seeing your picture, uncropped with exif. Need all the help I can get:smile:
     
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