Mystery Vivitar

[David]

So I got a Vivitar 75-200 for $13, including shipping, broken the other week. The aperture blades dripped oil and the internal lenses had some dust. After blowing the dust off the lenses with compressed air and cleaning the blades, I decided to keep the lens. Partly because I made a modification internally just to see what would happen.

But I'll get to that in a minute. My big curiosity about this lens is it's background. I tried to look up the info based on the SN, but the online Vivitar resource doesn't list who made lenses starting with "77." The full SN is 77209659.

As for the mod I made on the inside, the aperture range was controlled by a piece of metal on an internal arm. I took the little piece of metal off (it was screwed on) and the lens went from an f4.5 to 22 to an f9 to unknown. The old f22 setting was enormous compared to the pinhole aperture it now has when stopped down. This week I'll take some test shots at the old stop-down level and the new. If it fails miserably, I kept all the parts to undo the mod.

David

[walter g]

77 is Kobori made. I have a 80-200 made by Kobori that i really like.

[Arninetyes]

So, you've created the world's first pinhole zoom lens? Should be fun! Of course, IQ will be much like any other pinhole cam.

[David]

So I took the modified lens out last night to photograph with. It didn't fit onto my K-7. The mount said P/K, and even fit inside my K1000. So, when I got home (I didn't try it on my K-7 before going into the field... I know,) I was able to modify it to fit.

Most importantly, this demonstrates that Pentax's claim that ALL K-mount lenses will fit on ALL K-mount bodies is untrue. This lens had to be modified to fit. On the K-mount there's a spring-loaded arm that provides aperture interface with the camera. There's also a metal ring next to it for some reason. That ring was undamaged, but shaped differently (photos to come.)

So, the lens now fits. Photos to come later this week.

[RioRico]