The return of the Tessar

It's seems really odd, but with the launch of Canon's new 40mm f2.8, two Pancake AF tessar primes have been launched in just a few months, the being Pentax's razor thin 40mm f2.8 K-mount kit lens for their new mirrorless.  Before that, the last time a similar tessar pancake was launched was Nikon's manual focus  45mm f2.8 Ai-P lens.  These lenses have a simple optical design that yields excellent sharpness.  

I have a Nikkor 45mm f2.8 GN,  a tessar from the late 1960's that has had an Ai conversion.  This lens is also excellent, and interestingly, for me, it gets most of its use as a copy lens for film negatives, used with a PB-5 bellows.  It is the only lens that I could get to work consistently well with this set up.  The other interesting thing about this lens is it has markings for flash guide numbers, hence the GN name.

Nikon FE2 with Nikkor 50mm f1.2, copied to digital with a Nikon D700 and a Nikon PB-5 bellows with a Nikkor 45mm f2.8 GN