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Nikon DSLR Cameras
D7100
D7100 Inconsistent autofocus. Backfocus / front-focus
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<blockquote data-quote="Fred Kingston" data-source="post: 661278" data-attributes="member: 10742"><p>First... Let me explain micro or fine adjustment...</p><p></p><p>Cameras and lenses are made in factories. Quality control inspects to make sure the manufactured item is within a specific design tolerance. That tolerance as usually expressed as plus or minus X%.</p><p></p><p>Cameras are not mated with lenses and are made in a different factory. </p><p></p><p>So... let's us an example of a camera that meets the design spec but is +5%... It still meets the design tolerance of +-10% Now let's also assume your lens is +7%... It also is within tolerance... </p><p></p><p>Now when you add the +7 lens to the +5 body... the combination is no longer within tolerance...</p><p></p><p>neither component is broken... that's called cumulative tolerance error... The Fine or Micro adjustment lets the user adjust for that error... </p><p></p><p>The assumption is that the camera will be -1 and the lens +1 which would cancel out any error. Reality is, that's rarely the case.</p><p></p><p></p><p>Next issue I see in your images... you're shooting in low light, at 1/50th of a second... which is very slow, and you're also shooting with an aperture that appears to be wide Open... Most lesns, wide open, are very soft... </p><p></p><p>Here's a tip... Set your camera for single-point focus AF-S and turn on the Beep in the menus... now, when your camera achieves focus lock, the camera will beep to let you know that it has achieved focus.</p><p></p><p>Retest the camera and lens, but do it in bright light so that you can set the speed to 1/250 sec or faster, and close the aperture down to one or two stops off the f1.8 so you're not using softest lens setting...</p></blockquote><p></p>
[QUOTE="Fred Kingston, post: 661278, member: 10742"] First... Let me explain micro or fine adjustment... Cameras and lenses are made in factories. Quality control inspects to make sure the manufactured item is within a specific design tolerance. That tolerance as usually expressed as plus or minus X%. Cameras are not mated with lenses and are made in a different factory. So... let's us an example of a camera that meets the design spec but is +5%... It still meets the design tolerance of +-10% Now let's also assume your lens is +7%... It also is within tolerance... Now when you add the +7 lens to the +5 body... the combination is no longer within tolerance... neither component is broken... that's called cumulative tolerance error... The Fine or Micro adjustment lets the user adjust for that error... The assumption is that the camera will be -1 and the lens +1 which would cancel out any error. Reality is, that's rarely the case. Next issue I see in your images... you're shooting in low light, at 1/50th of a second... which is very slow, and you're also shooting with an aperture that appears to be wide Open... Most lesns, wide open, are very soft... Here's a tip... Set your camera for single-point focus AF-S and turn on the Beep in the menus... now, when your camera achieves focus lock, the camera will beep to let you know that it has achieved focus. Retest the camera and lens, but do it in bright light so that you can set the speed to 1/250 sec or faster, and close the aperture down to one or two stops off the f1.8 so you're not using softest lens setting... [/QUOTE]
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Nikon DSLR Cameras
D7100
D7100 Inconsistent autofocus. Backfocus / front-focus
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