Hi all, Here's a question I've been thinking about lately. I finally found a dedicated flash module for my Sunpak 444D flash, and I'm thinking of some things to try with my TTL-capable body (an MZ-50). I'll get an answer for myself with some upcoming experiments, but thought I'd ask the group anyway. We're all familiar with the limitations of the ZX/MZ-50 when using pre-A lenses. Regular TTL metering works properly as long as the lens aperture ring is set to wide-open aperture, and pictures are underexposed if the aperture ring is stopped down by the user. This is the case when one is metering and exposing under *ambient* lighting , but it occurred to me that shooting under TTL flash metering might be a bit different. So here's the slight twist. Suppose I want to shot some photos with a pre-A lens under very dim (or perhaps completely dark) ambient lighting. Perhaps an extremely high-magnification macro shot, for instance. Instead of using ambient light and exposing for a LONG time, however, I'm going to use an off-camera TTL flash. The MZ/ZX-50 will recognize my flash and set its shutter speed to X-sync. What happens if I now decide to manually stop down the aperture ring to give me good depth of field? I'm assuming that regardless of where I choose to set the aperture ring, the body will simply keep the flash illuminated until it sees that enough light has entered the lens. Seems like the open-aperture reading -- before the flash fires -- should be totally irrelevant in this case, and it shouldn't matter where I set the lens aperture ring. Is my assumption correct? This seems like it would be the "correct" way to design a TTL flash metering circuit. Anyone tried this sort of thing? Any help appreciated. Thanks in advance, Bill Peifer Rochester, NY - 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 .
