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Nikon DSLR Cameras
D7100
Focus issue, AF fine tune?
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<blockquote data-quote="Horoscope Fish" data-source="post: 610501" data-attributes="member: 13090"><p>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.</p><p></p><p>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.</p></blockquote><p></p>
[QUOTE="Horoscope Fish, post: 610501, member: 13090"] 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. [/QUOTE]
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Nikon DSLR Cameras
D7100
Focus issue, AF fine tune?
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