D7100 Owners: Test the left AF accuracy before you keep it!

Started Mar 24, 2013 | Discussions thread
photomunkey
New MemberPosts: 13
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Re: You used auto
In reply to Mako2011, Mar 25, 2013

Mako2011 wrote:

I downloaded your tests and checked the focus points. The problem is you used AF-Area mode "auto" for all the tests. Using the 35 f1.8 in that way will often result in that kind of outcome. There's no consistency in that mode with targets like that. The camera is seeing very different geometries in your left and right test. Using the 35mm f1,8 can compound it. Too actually test for the left and right AF issue...you should have used AF-Area mode "single" and then done a left and right CDAF comparison with the 35mm f1.8... under bright non-tungsten light. You may (not 100% sure) have returned a camera that was actually operating correctly. With the replacement body...be sure to test using "single"

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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)

I'm on my 2nd D7100 from B&H. Tested both bodies with 5 different lenses, including a brand new Sigma 17-50mm f2.8 OS HSM lens at 50mm. AF-S, single point, tripod mounted.

First body had severe back-focus on left and right outer AF points at the rule-of-thirds lines. Was generally consistent on the center point.

Second body has moderate back-focus on left and right outer AF points at the rule-of-thirds line, but is better (closer to correct) on the right side. Center AF point is offset about 1/3 of the way out of its "box" and center AF with single point will miss focus 4 out of 10 shots, mounted on a tripod with nothing at all moving, not even the test target tree which is as wide as a single AF box. When the camera missed the focus, it nailed it on the curb across the stree about 60-80 feet away! Go figure. Second body works not too bad at f3.5 on the outer points, and a "consumer" lens probably isn't so great at the outer points, but my Sigma 70-200mm f2.8 OS HSM IS good at those outer points, and it does the same thing as my Nikon 50mm f1.8D does. It simply blows any focusing done outside of the center 9 AF points.

I will be calling up B&H after this long weekend as the second "new" body arrived with approx. 1200 shots on it already.

My .02 says there is a SEVERE calibration issue with D7100 bodies in the information I have gathered from here and NikonCafe.com. You can look me up as "rotarymunkey" on Flickr if you want to see samples of the first body's performance. I haven't put up the samples from the second body, and might not as it does no good to stir the pot. There's an issue, and if Nikon follows Nikon's typical approach (a la D800 and D600 concerns) they're going to wind up punching themselves squarely in the face with this launch too.

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