PV+OVF+MF Still unaddressed in the D850

Started Oct 18, 2017 | Discussions thread
Marianne Oelund Veteran Member • Posts: 7,788
Incorrect AF concept

ArthurMeursault wrote:

It was this way with the D810 and the tradition continues with the D850.

While using the OVF depressing the PV button to account for focus shift eliminates the view of the focus indicator while attempting to critically focus a manual lens.

Critical focus still only available through a loupe and using the rear screen.

C'mon Nikon..... you can do better.

Using the Preview button to stop the lens down, cannot cause AF to account for focus shift, therefore there is no reason to attempt doing so - or for Nikon to support the action.

The aperture used by AF has nothing to do with the lens diaphragm position - except that if you stop down past f/8 you will completely cut off all light to the AF module and AF can no longer operate.

Phase-detect AF uses its own fixed aperture, defined by a mask within the AF module .  It cannot "see" the effects of lens focus shift, although some Nikon camera bodies made since 2014 do have the ability to compensate for focus shift by applying a predictive algorithm.

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Source credit: Prov 2:6
- Marianne

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