> (yes, I'm aware the obvious answer is a giant battery pack) Ah, I see that you caught on fast, Glen - good for you - <g>.
> Hi.. Last night a used lens I bought from Adorama arrived at my > door, and I'm a little confused by it. <heh-heh> > Its a 35-70mm f2.8 zoom. The one and only. You've just took ownership of a Pentax AF (not FA) 35-70/2.8 Zoom, designed specifically for the MEF body, circa 1981. > What baffled me about it, though, was the > giant battery pack looking lump hanging off the bottom of it. That's to hold four AAA batteries, to run its built-in AF motor. > My question is, does this just use normal AAA batteries Yes. > and will it work correctly with my ZX5n Well, yes and no. It will work on a ZX-5N about the same as any other pre-A manual focus lens will. However, it will not autofocus with any body except the MEF. And, although a quick glance at its K-mount might lead you to think that it has the A lens contacts on it, they are actually in a different place on the mount, and (again) only work for focusing with the MEF. > or is this some sort of specialist lens that will only work in AF > mode with some other model of body? Now you've got it - just the with the MEF. The MEF was Pentax's first entry into the world of AF camera bodies, and the AF 35-70/2.8 was the first lens to be designed with the new Kf mount for use with the MEF. The MEF sort of represented a mid-point in the transition of AF from putting everything inside the lens. There was at least one Vivitar telephoto, I think it might be a 200mm lens, that would autofocus with any body, since all the electronics needed were put inside the bulky lens barrel. The AF 35-70/2.8 moved the AF sensory functions inside the body, but left the AF motor in the lens. Eventually, of course, the sensory and motor functions all migrated into the body. Since the MEF and its "first" lens were not a great success, Pentax never followed up with any other Kf of AF (not FA) lenses. Basically, on any body except for the MEF, the lens acts as a fat and heavy K-series or M-series zoom. It does focus manually (feels a lot like many of the F lenses that lack AF/MF clutches - there's a thin knurled ring at the front of the lens that can turn to focus, while trying to avoid getting your fingers into the field of view, while trying to ignore the whirring feel and sound as you turn the ring. Optically, this lens has been disparaged somewhat here on the PDML, but it actually has tested out pretty well in the photo magazine lens tests of its day, and I do think that it is a shame that Pentax never released a "trim" MF-only version of the lens design. Oh well... > Also, its the first lens I've ever used that you pull and push it > to determine the focal length. Well, this is actually a pretty common feature now on so-called "one-touch" zooms, where there is a combined focus and zoom ring that is generally pulled or pushed to zoom and rotated to focus. > Do the weird little buttons on the barrel have any effect on this, > or are they just there to hold the thing together? Those little buttons are used to activate the autofocus action of the lens (when mounted on an MEF body). So, will Adorama shortly be receiving a call, Glen? Fred - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
