So I took a look and here’s what I saw comparing a phase version of the CF N 10/0.30 Nikon with a brightfield version. The brightfield Nikon CF N 10/0.30 Plan Achromat produced a slightly better stack. Not by a huge amount, but it was noticeable, especially toward the edges. I’m always leery to judge by the stacked images so I compared similar individual frames and the conclusion was the same. I can’t say if this is simply a lens “sample” variation or whether it is due to the presence of the phase ring.
One thing I did notice, that was obviously due to the phase ring, was the appearance of out-of-focus areas. Now I realize that “bokeh” is not a concept used too often by us stackers
, and since the software will select the sharp sections most of these OOF section will be ignored. (There will be some pictures with large OOF areas where this could be an issue). But it does make me wonder if the phase ring is also having a subtle effect on the “in-focus” areas as well. If I already owned only the phase I would certainly use it. Both are capable of producing great looking images. But if I were looking for an objective with the primary purpose of putting it on a camera bellows I would probably skip the phase version and keep looking until I found the brightfield.
This subject was chosen only as a “test” (not intended to be a pretty picture!). Both images treated exactly the same. Slight sharpening after resizing, and that’s all.
brightfield objective
phase objective
part of single image from stack. Phase (top), brightfield (bottom)
