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Monday, May 12, 2008

Followup on Nikon D3 focusing

I recently sent my Nikon D3 into Nikon in order to rectify a manual focus problem; Nikon replaced the focusing system according to the repair notes. But it still isn’t right, or at least not as reliable as I expect and quite probably no better than before.

I used the Zeiss ZF 100/2 Makro-Planar (I also cross-checked yesterday with the Nikon 105/2 DC to eliminate the lens as a variable—same problem). I ran two tests: the first was of a test chart, and the second was of a outdoor subject in full sun. For the Canon 1DsM3, the Zeiss ZF 100/2 Makro-Planar was used with a Cameraquest Nikon-to-EOS lens adapter. All shots taken at f/2.

Focus accuracy success rate
Camera B&W Test target
Outdoor scene
Nikon D3 + “E” screen 0/8
(backfocus)
N/A
Nikon D3 + standard screen 5/8
(backfocus)
3/10
Canon EOS 1Ds Mark III 6/6 8/10


Not only did focusing seem easier with the Canon EOS 1Ds Mark III (less ambiguous and easier to distinguish in-focus image), the results speak for themselves; the 1DsM3 absolutely nailed the test target with spot-on manual focus down to the millimeter.

By comparison, the D3 with the “E” screen was off (back-focused) all 8 of 8 attempts—hopeless. Results were better with the standard (as-shipped) D3 focusing screen, but still unacceptably variable. The only variable left to eliminate is the DK-17M magnifying eyepiece. I had previously tested for that issue, but found no improvement—I’ll do it again and re-verify.

WTF? What do these results mean? Is the camera still defective after repair, or is it just that it’s harder to manually focus a Nikon D3 as compared with focusing a Canon EOS 1Ds Mark III? Maybe it’s worth sending the D3 into Nikon service for a recheck, but gosh that’s frustrating.

test target focus accuracy Nikon D3 Canon EOS 1Ds Mark III

no backfocus actual pixels test target
Test target — manual focus, 6/6 like this
(Canon EOS 1Ds Mark III + Zeiss ZF 100/2 Makro-Planar)

backfocus actual pixels test target
Test target — manual focus showing backfocus with standard screen, typical
(Nikon D3 + Zeiss ZF 100/2 Makro-Planar)

Note that the color fringing seen above is a clean sign of being out of focus, and a behavioral characteristics of non-apochromatic lenses. See “What color is your background?”.

ATW wagon Canon EOS 1Ds Mark III + Zeiss ZF 100/2 Makro-Planar

actual pixels Canon EOS 1Ds Mark III manual focus perfect
Outdoor test scene—the wheel on the wagon — manual focus, typical
(Canon EOS 1Ds Mark III + Zeiss ZF 100/2 Makro-Planar)

actual pixels Nikon D3 manual focus error
Outdoor test scene—the wheel on the wagon — manual focus, typical
(Nikon D3 + Zeiss ZF 100/2 Makro-Planar)

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