Accura Diamatic 300/5.5 - Frankensteins lens monster !

[luisalegria]

I picked this thing up for 99 cents (plus shipping) -



This used to be an automatic YS-mount lens (interchangable mount system with aperture linkage based on the T-mount thread). I have no firm idea who made it, but it looks a lot like a preset lens series that may have been made by Tokina, and Tokina had a thing about f/5.5 for 300mm's. But I didn't think Tokina ever did YS-mount anything, they weren't part of that consortium. But anything is possible.

But someone had, for some odd reason, converted this to be a manual Exakta mount, by removing the aperture linkage and replacing the 42x.75 T-thread ring with an Exakta mount ring, rather crudely. And of course they changed the length to get the back focus right for Exakta (which is @10mm off from native T or YS mount), by screwing with the stops on the helical. The trouble with that is that there are static elements near the diaphragm that don't move while focusing, so this sort of tinkering is likely to get everything out of alignment.

So I replaced that kludge with a PK->M42 adapter - just drilling holes in the right spots, and trying to get the helical to where it gives me infinity.

I wasn't expecting much (there has been a little too much, er, surgery done to this thing). But it turns out that Frankensteins lens monster has special powers. This is a pretty good lens, sharp at f/5.5, high contrast, little flare, pleasant to use. Goodness knows whether its better or worse than it was when new. I hope it doesn't still want revenge on its maker !

All at f/5.5 as it was a dim and foggy day at the zoo.













The bird, well, no, the ape -

I messed up on this shot, as there were plants in the way, and I haven't fixed it properly -



100% crop -