Nikon D850 specs of interest

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Andy Davies
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Nikon D850 specs of interest

Post by Andy Davies »

Auto-focus-bracket mode–the camera can take up to 300 pictures, varying focus between from close-infinity. User can choose 10 levels of focus steps. Roughly 5 FPS, can be software stacked.

ray_parkhurst
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Post by ray_parkhurst »

To do this at magnifications above 1:1, I would assume an appropriate prime lens would be focused "near" infinity, but not quite, and then an infinite objective (or reversed prime/enlarging/etc lens) coupled to it. This would give some +/- focus adjustment using the prime lens' electronic focus. I have not tried this method, but I'm confident others on the forum have, and would share their insight. How well does the method work? Is the typical minimum focus step small enough to step smaller than the DOF at, say, 10x magnification?

Seems likely this functionality was created not for photomacrographers, but for landscape or similar photography where extreme DOF from close to infinity was desired. I'll be curious in responses about how well it works for PM applications.

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Post by rjlittlefield »

ray_parkhurst wrote: This would give some +/- focus adjustment using the prime lens' electronic focus. I have not tried this method, but I'm confident others on the forum have, and would share their insight. How well does the method work?
The method works fine, up to the limit of aberrations that can be induced with high mag objectives that are dragged too far away from their design point.

See discussion at AF motor focusing with a microscope objective
Is the typical minimum focus step small enough to step smaller than the DOF at, say, 10x magnification?
That question is frequently asked, but it's never a real issue as long as the rear lens is internal focusing.

The reason is this: the front lens simply makes a small object that is physically close, look like a large object that is much farther away.

If the rear lens has fine enough granularity to stack a physical large object far away, then it can also stack the virtual large object that is created by the front lens.

It's a pretty safe bet that the rear lens does have sufficiently fine granularity, because if it didn't, there would be physical large objects that it could not focus on, and that would lead to unhappy users and bad product reviews.

--Rik

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