ckatosmith wrote:According to Nikon's website, it is CFI E Plan Achromat 10X/0.25 with WD 7.0. It has a 25mm thread and is MRP70100, also OFN20 (what's that?). Has THIS objective been tested here on the forum? I tried the search function...
I cannot recall ever seeing a test report for that objective. I can find a few references at photomacrography.net using Google search, but none of them are accompanied by images or comparisons to other objectives.
Based on its placement within the Nikon line, I would expect it to behave optically very similar to the CFI BE MRN70100.
OFN20 refers to the "field number", which is just the diameter in mm of the eyepiece field for which the objective is designed.
However, modern Nikon objectives typically deliver good image quality over a much larger circle than they are specified for.
Based on the MRL70100, I would expect the MRP70100 to cover APS/C with no problem at all (28 mm diagonal). Iit might well cover full frame with pretty good corners also (43 mm diagonal).
The MRP70100 is part of Nikon's CFI60 series [REF
]. This means that it has 25mm threads and a "parfocal" distance of 60 mm from the shoulder of the mounting threads to the in-focus subject.