On Friday, December 14, 2001, at 09:28 AM, Kent Gittings wrote: > It's the "A" function that matters for multi-segment metering as I > remember. > The manual should have said that.
After experimenting and studying up on the K family of mounts at http://www.BDimitrov.de/kmp/ (and http://www.BDimitrov.de/kmp/extras/K-mount/Ka.html in particular) I've determined that this is not the case. According to the (ZX-5n) manual, multi-segment metering works in manual mode, including with A lenses. As such, the "A" function must be irrelevant to multi-segment metering. Furthermore, the manual appears to be incorrect in stating that multi-segment metering only works with F and FA lenses in aperture priority mode. This is logically inconsistent with it working in manual mode with A lenses. What IS important for multi-segment meting is that the camera knows the aperture range of the lens, in particular the maximum aperture. (The 5 pins on the body make up a binary coding with 2 bits for the minimum aperture and 3 bits for the maximum.) Further evidence are notes in the manual about various functions not working correctly with the A 50/1.2 lens when it isn't in "A" mode. The way the aperture range encoding works, this lens is indistinguishable from an M lens unless it is in the A mode. And to answer my own question, multi-segment metering DOES work with an M lens if you simply modify the mount to provide insulation from the appropriate contacts on the body. I first used little bits of tape over various contacts on the body to see if it worked. When I determined that it did, I applied dots of fingernail polish to the mounting surface on the lens...we shall see how long that lasts. I have a few test shots on the end of one roll developed so far which turned out as expected, but I'll do some more extensive tests make sure there are not any oddities. -john - 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 .
