Continuation of my Nikon D4 assymetrical AF saga Part III

Started Jun 16, 2013 | Discussions thread
surrephoto
Regular MemberPosts: 219
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Re: Continuation of my Nikon D4 assymetrical AF saga Part III
In reply to chlamchowder, Jun 19, 2013

chlamchowder wrote:

I've played with many lenses and conclude that 50 1.4D is a great lens for this test due to CA & sharpness properties and you can easy judge a left or assymetrical AF problem on various bodies while utilising the 50 1.4D. The standard test for this problem for the D800 & also various maintenance test for many pro bodies also involves a custom calibrated 50 1.4D based on my knowledge.

That's interesting. I have a 50/1.4 pre-D AF lens, which I assume has exactly the same optics.

But I've also heard that the left focus problem gets more obvious when wide angle lenses are used. I remember hearing people saying that it was really severe with a 28/1.8 or something like that, and pretty much unnoticeable with a 200mm or so lens.

I guess it's completely off topic, but do you notice some purple halation when using the lens wide open, particularly in very bright sunlight? It's kind of like a purple glow around high contrast edges. It's usually not a problem at all, but kind of changes the 'look' of things when the lens is used wide open in bright sunlight.

Yes, yes, & yes.

It's true that wide-angle lenses are most affected, but most good modern wide angles, eg. 24 1.4, 14-24 f2.8g, are not that bad in the CA category, and relatively less precise in focus (due to the inherently larger depth of field) so test results on the 50 1.4D seem to be much more compelling at least to myself.

The 50 1.4D seems to have serious CA and halation when the subject is hit with a healthy blast of direct sunlight. But fortunately sharpness is not affected. That huge glowing CA certainly renders the lens rather unusable for color photography if you expect it to shoot at f1.4.

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