Nikon 105 f/1.4

Started Aug 25, 2016 | Discussions thread
MOD Marianne Oelund Veteran Member • Posts: 7,868
Focus Shift: Not good news for AF

Westmill wrote:

Has anyone checked this lens for focus shift yet ?

I made some measurements this evening, for focus shift near minimum focus distance (just under 1m).  There is a substantial amount.

Starting with focus at f/1.4 as the reference, the focus plane moves back slightly to +2mm at f/2, then makes a large jump to +7mm at f/2.8 and to +10mm at f/4.  I did not test beyond f/4.

This amount of focus shift is almost exactly the same as the 85/1.4G at its minimum distance (0.85m), which is not surprising as I found the level of SA to be very similar between these two lenses.  (However, the 105 is dramatically improved over the 85, with regard to secondary LoCA.)

If you are planning on using the lens primarily at f/1.4 to f/2 (as I am) then the focus shift shouldn't be an issue.  However, if you need to move back and forth between the widest apertures, and moderate ones, AF will be problematic, especially with camera bodies released prior to 2014 (starting that year, Nikon incorporated focus-shift compensation into the AF system - without telling anyone, of course).

For example, my D800E at close distances needs +10 to +12 AF fine-tune at f/1.4 or f/2, but it changes dramatically to -8 at f/2.8 and -18 at f/4.  These measurements were made under daylight-balance (about 5000K) LED lighting.

The current-generation D500 fares better, with 0 to +2 fine-tune at f/1.4 or f/2, -6 at f/2.8 and -10 at f/4.  Moving back to 2m distance, the numbers were essentially unchanged.  I'm hoping this will improve when Nikon release new lens data.  In the meantime, users need to be aware of this issue with AF when using the 105/1.4E.

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Source credit: Prov 2:6
- Marianne

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