A strange lens

link

Greg

I saw something very similar with "Sears" branding a while ago, it was listed in the USA and postage was a bit ridiculous. Both rather resemble this prototype AF zoom from 1976.

A similar principle to this lens I guess. It was designed to be used with the Pentax MEF body I believe.

I think the two I mentioned had the AF kit inside the lens, rather than communicating with the body. The prototype is shown on a K2DMD, which didn't have any way of communicating with the lens. It can't have been terribly reliable that way and the lens looks ridiculously heavy and bulky.

Considering that the ME-F is apparently very slow to AF by modern standards (and was presumably much better than these early contraptions) I'm not entirely surprised they didn't catch on!

I plan to overhaul my ME F this year and give it a try (needs new light seals, new baseplate and new focusing screen but is otherwise tidy and working). I don't have the matching lens but the focus confirmation lights will work with any lens, so I can see how good it is at deciding focus compared to my eyeball and the split screen.

Tamron did at least one Adaptall zoom lens with built in AF that worked on MF bodies. Perhaps Pentax originally intended to have a AF lens that worked with all bodies

The prototype on the K Mount Site is described as using "Honeywell Visitronic technology". I presume this was some sort of collaboration between Pentax and their US distributor, although I'm not sure who made the optics.

Given the focal range of the lens I would wonder whether this had any impact on the two M series 35-70mm lenses. I seriously suspect that the M 35-70mm f2.8-3.5 was originally going to be a K series lens but took too long to develop - there's a K 35-70mm f2.8 listed in the prototypes section of the Dimitrov site which looks identical to the M series lens which reached production, and which the production AF lens was evidently based on.

Honeywell Visitronic technology refers to their AF module, the first of its kind. The AF system was then licensed to whoever wanted to use it.

Seem to remember that Vivitar also had something like that in the mid 80s.

Same lens. Sears(& Roebuck back then) sold cameras made by Ricoh under their own label. link