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  1. #11
    Senior Member
    Eob's Avatar

    Re: Focus issue, AF fine tune?

    Quote Originally Posted by Horoscope Fish View Post
    Well I think your options are as follows:

    1. Just jump in and adjust the AF Fine Tune setting in small increments until you see an improvement. This won't be the most precise method but it should help and it requires no special equipment (tripod, test target, etc.)

    2. Invest in the necessary tools, such as a tripod and test target, and do a proper job of things.

    3. Send your lens to a professional and have them do the adjustment for you.
    thanks, I'll give that a try

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  2. #12
    Junior Member

    Re: Focus issue, AF fine tune?

    Quote Originally Posted by Horoscope Fish View Post
    Many things can cause a photo to have less than pinpoint focus. For instance, are you keeping the shutter speed at, or above, 1.5 times the focal length you're shooting with? That was a real sharpness killer for me when I was shooting DX.

    Should you decide you want to do a proper test for front/back focus you're definitely going to want a decent tripod. That aside, though, there are ways you could at least do a rough test to see if there's an issue with front/back focus. I wouldn't make adjustments based on this sort of rough testing but it should help point you in the right direction. What you might try is using a ruler, yardstick or tape measure instead of one of those paper test-targets. When I started testing I used a ruler, leaned at a 45 degree angle, against a stack of books. I focused on a chosen number on the ruler and shot handheld. Two critical aspects to this testing is shooting the lens at it's widest aperture (e.g. f/1.8) and placing the target at the proper distance which is 50 times the focal length (e.g. 50mm lens has a focal length of, obviously, 50mm; so the math is 50 times 50, which gives us 2,500 millimeters which is two-and-a-half meters or just over eight feet)). You'll want enough light on your target so that you can shoot at 1.5 times the focal length or (e.g. about 1/125 for a 50mm prime) at ISO 100. You want the ISO as low as possible so digital noise doesn't give the appearance of improper focus of course.
    Thanks for this procedure. I hip-shot something similiar when I was dissatisfied with the AF using a Tokina 11-16 on my D7200. I shot a tape measure on the floor at a 30` angle. Because of the low angle I couldn't reliably make out a target number on the ruler so I put a pen on the floor adjacent to the tape and aimed the spot focus circle where it touched the tape. Got some improvement. I'll get meticulous with your procedure and report here.

    Sent from my SM-N950U using Tapatalk

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