Nikon AF-S NIKKOR 28mm f/1.8G

AchimT

AchimT

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I read a review in which it said that this lens has a focus shift when stopped down. I'd like to ask two questions:

- what does this statement mean (I'm not a native English speaker, so I wonder whether the statement is clear and am just not aware of it). Does the statement mean that
a) if the aperture is stopped down after having already focussed, the focus will be lost and you have to re-focus, or
b) the AF works correctly when the lens is wide open, but once stepped down, it develops a front- or back focus which needs to be corrected in the camera's AF fine tuning

Has anyone used this lens on a D800 /D3/D4/D600, and has this happened to you?

Thanks for the info!
 
Hi, (very very basic) my understanding is this, but I am happy to be corrected by someone more knowledgeable.

The camera will always use the 1.8 aperture to attain focus, regardless of the aperture selected in camera. The aperture then changes to the selected aperture when the shutter is pressed. When the aperture changes the focus shifts away from the focus attained at 1.8, meaning that focus at other apertures can be off. It is not possible to fix this by using AF fine tune as the shift varies by aperture, so each aperture would require AF compensation and this can not be done. The best that can be done is calibrating it to the most used aperture.

I have this lens, but have not had a chance to test it out. Using live view it is amazingly sharp in my view.
 
Thank you for this explanation!

I have meanwhile read two more reviews which describe the same issue. It is my impression that steps can be taken to get good pictures with this lens despite the issue (probably as you say by calibrating it in-camera for a certain aperture range).

The lens looks pretty good in every other aspect, especially sharpness. I'd be interested in buying it too, but worry how difficult it will be to use. OTOH, if you calibrate it for, let's say, f5.6, then at f8 and f11 etc. the better DOF might make the focus issue unnoticeable?

If you can, it would be great if you'd describe your experience with the lens once you've had time to take a few pictures.

Thanks again!

BTW - you've got some really beautiful pictures there on flickr!
 
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Thank you very much, the first one in the photostream was taken with this lens a few days ago. I also took a landscape orientation one and as very impressed with the lens.

I was worried about buying it because of the focus shift issue that I have read about. I did a (non scientific) test yesterday with a tape measure focussing and stopping down, and could not see it as I stepped down from 1.8 to f11. I will give it another go in the next few days to see if I did it properly and hopefully and report back. At the moment I am happy with it, especially as I use it stopped down.
 
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