Cnscope Metallurgical Again - 10x/0.25 This Time

I was pretty happy with the 4x/0.1 CNScope objective, so I picked up the 10x as well. Probably not often needed for numismatic purposes, but I thought it would be worth a try.

1957-D RPM CNScope 10x/0.25 test by CaptainFwiffo, on Flickr

This is at roughly the rated magnification of 10x, of a 1957-D RPM that has become my standard test coin.

It has some pretty serious fall-off in sharpness in the corners, but the fast 0.25 numerical aperture (equivalent to something like f/1.8 infinity f-number) shines in the center of frame.

Here's a 1:1 crop:

1957-D RPM CNScope 10x/0.25 test (crop) by CaptainFwiffo, on Flickr

For comparison, here's the 4x/0.1, 100% crop with the same coin:

1957-D RPM CNScope 4x Metallurical Test (crop) by CaptainFwiffo, on Flickr