Using AF Fine Tune with D300 Infinity Focus Problems?

Discussion in 'Beyond the Basics' started by iflynething, Mar 31, 2009.

  1. iflynething

    iflynething TPF Noob!

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    I just was able to get a great deal on a 80-200 2.8. Incredible lens and it's super sharp.....so i though.

    Many others that I used wondered why they weren't as sharp as I KNOW it should be. Luckily, my new D300 has the AF Fine Tune. I have not tested it on an actual focus chart yet but during a dance compeitioin I messed around with this function. Anyways I got it pretty spot on. I was at another location and found a horizontal rope to look at and just focused on there. I ended up at being at -14 (points, marks?) to make it focus correctly....(as far as I could tell in the viewfinder and from the shots I got)

    Having this much front focus and having to correct so much (-14) will it affect how the camera focus at infinity? Will it even be able to focus at infinity?

    Also, I was fine tuning at 200mm. Will it make a difference shooting at 80 or will the same parameters be the same for all focal lengths?

    ~Michael~
     
  2. Sw1tchFX

    Sw1tchFX TPF Noob!

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    what's the distance?

    the 80-200D is known to misfocus and be really soft near it's minimum focus distance.
     
  3. iflynething

    iflynething TPF Noob!

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    I didn't know that. For the dance photography, it was about 100 feet but what I was doing at the rope was about 10 feet, probably more but I know it wasn't the minimum focus.

    It's pretty spot on right now at the -14 I have it at right now.

    Is there any good technique to focus test other than pointing at a 45 degree angle and going from there?

    ~Michael~
     
  4. JerryPH

    JerryPH No longer a newbie, moving up!

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    I played with this and read up on it. As far as I can tell, the general results that came out of that for me were that this was not really a means to correct a portion of small focal range of a lens, but the entire range.

    I put on a lens that I knew back focused ever so slightly to the point that it was impossible to see this anywhere else but on a well magnified focus chart and only when set to F/2.8. This option corrected the back focus everywhere throughout it's entire focal range by using a setting of -1 to perfection through out the entire focal range, and had no effect on focus to infinity that I could tell.

    If a lens back focuses, it normally does so everywhere. The methods provided in the D300, D700 and D3 globally correct this condition to perfection. But, if you have a mechanical issue where you get a misalignment causing focus issues at different focal lengths, this option is NOT meant to correct for that... and the only solution to that is to send it in to the manufacturer.

    Just my 2 cents.
     
  5. JerryPH

    JerryPH No longer a newbie, moving up!

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    That -14 seems pretty high to me, suggesting a potential hardware or mechanical issue, but I am no expert.

    That focus test chart is pretty much the best way right there. Also be sure to get as close to 45 degrees as possible, it can have some negative effect on the test results the further off you are away from that angle. If it is less than 45 degrees, it will show less of the error or misfocus. If it is more than 45 degrees the back focus is amplified and gives greater "wrong" results.
     
  6. iflynething

    iflynething TPF Noob!

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    Thanks Jerry...your new avatar really throws me off sometimes.

    I too though that -14 was WAY too much but that is just going from what I was shooting and getting an estimate at what it should be set at. I could tell that when set at 0, it definitly front focused (I believe I"m using it the right way - at 0, the focus point is in front of where it's supposed to be). I just bought this lens and I wasn't able to take it home to test for focusing problems. I guess no lens is going to be perfect. What would I be looking at for a Nikon calibration?

    Is there a good way to know if I"m at 45 degrees or not with some lines and a protractor? I only have a small one, so I'm wondering how I'm going to know if I'm set up to 45 or not.

    Thanks alot for the information

    ~Michael~
     
  7. Garbz

    Garbz No longer a newbie, moving up!

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    Errr why are you even asking us if it will focus at infinity. It's your lens go outside and point it at something on the horizon and tell us if it focused or not.
    Also if you just bought the lens it will cost you nothing to get it sent back for correction.
     
  8. JerryPH

    JerryPH No longer a newbie, moving up!

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    My local hardware store has a metal ruler with a sliding section that contains a water level that is adjustable. I set it at 45 degrees and leaned the ruler against the lens and adjusted the tripod until the water level was perfectly level. then I locked things down, and took the pictures. Now... some manual adjustment of the paper may be needed, but once that is done, tape the focus test chart down and shoot away.
     
  9. shivaswrath

    shivaswrath TPF Noob!

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    woah, didn't even know the d300 could do that!!! Cool info for those that are considering. . .
     
  10. iflynething

    iflynething TPF Noob!

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    Thats a good point! I bought it used, so I assume it will cost to get calibrated?

    ~Michael~
     
  11. JerryPH

    JerryPH No longer a newbie, moving up!

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    It gets better. The camera can remember the different settings from several lenses that you calibrated for.
     
  12. iflynething

    iflynething TPF Noob!

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    Ha that's one of the cool parts. As far as I know, you have have up to 12 in the main menu and up to 99? Correct me if that number is wrong

    ~Michael~
     

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