D600 + 28mm 1.8G Back Focus

Started Jan 31, 2013 | Discussions thread
anotherMike
Veteran MemberPosts: 7,027
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Re: I returned the lens
In reply to MarceloLI, Feb 4, 2013

I can't say your issue is a problem with the lenses inherent design (which does include some focus shift and definitely some field curvature, but in your scene neither would have affected the outcome much), and thus, blaming Nikon on releasing lenses "with problems" is inaccurate.

Your issue is one of or a combination of any of the following:

a) Expecting too much performance from a 1.8 lens shot wide open on a high rez body

b) AF miscalibration

c) Improper AF point selection (where you placed the AF sensor on the face)

d) The lack of precision of todays AF systems when dealing with situations where a wide angle lens is used wide open on a target with less-than-amazing contrast.

Personally, and speaking as someone who believes in testing/evaluating their gear to understand the limits of said gear, and as someone who is about 2/3 of the way through an extensive test series on the 28/1.8G, I would have done the following:

a) Shot the scene at F/2.5, or at least F/2.2, which is a stepping stone up in terms of sharpness on this lens compared to wide open. I don't own ANY wide angle that is tack sharp on my D800E, not even the Sigma 35/1.4 or the Zeiss 21/2.8 - ALL of them need to be nudged down the aperture dial a bit.

b) If the lens showed AF calibration issues, I would have sent it back to Nikon service for AF calibration, or returned the lens for another sample. In my case I generally do the former. BTW, on your calibration example, I feel you over-corrected the fine tune.

c) Made sure I shot the scene a few times with refocus in between since I'm aware of the inaccuracies of the current generation of AF systems with wides, fast apertures, and lower to medium contrast focus targets.

As for the lenses focus shift and field curvature, having been testing a bit now, it tends to manifest itself as a behavior one has to "learn" mostly with horizontal landscape scenes where one is trying to have definite clarity in all parts of the scene from front to back and side to side. I'll say this though; once you have figured out the focus point on such a scene (where the combination of field curvature, focus shift and DOF all combine to help you out in a beneficial way), this lens is capable of stunning results, results well above the price point of this lens. WELL above the price point.

-m

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