William, The biggest flaw I see to Tom's observations is when you bounce or diffuse the flash. How would the body go about knowing that is what you are doing? In those cases, you should see severe underexposure. My experience is that they work fine.
Bruce Dayton Wednesday, March 13, 2002, 11:54:55 AM, you wrote: PWO> Bruce Dayton wrote: >> I have often wondered what the metering pattern is for the TTL sensor >> - I'm guessing it is center-weighted. That could also account for >> some differences. PWO> Hi Bruce, PWO> I've wondered this same thing, and I'll bet you're right about the PWO> center-weighted pattern. Somebody shot and posted links to a whole series PWO> of TTL flash shots of some shiny metal object against a fairly neutral PWO> background, a few months back. A bunch of different apertures, shutter PWO> speeds, etc. Can't remember who it was -- I was thinking it was either you PWO> or Doug Brewer, but I just can't remember. I remember the look of the PWO> shots, though. As best as I can recall, those shots appeared as though the PWO> TTL flash metering was center-weighted, or pretty darned close to PWO> center-weighted. There were some overexposed shots at the fastest apertures PWO> that were attributed to the flash not being able to quench in time. PWO> I guess the way to test Tom V's idea (about the possibility that the flash PWO> intensity is calculated from distance and guide number information, but not PWO> controlled by an actual TTL sensor reading) is to fire a test shot with and PWO> without the lens cap in place. If the TTL sensor doesn't matter, then the PWO> flash intensities for both of these test shots should be about the same, and PWO> the recycle times should be about the same. If the sensor really ~is~ PWO> metering and controlling flash output, then the lens-cap-in-place test shot PWO> should have a ~much~ longer recycle time. PWO> Bill Peifer PWO> Rochester, NY PWO> - PWO> This message is from the Pentax-Discuss Mail List. To unsubscribe, PWO> go to http://www.pdml.net and follow the directions. Don't forget to PWO> visit the Pentax Users' Gallery at http://pug.komkon.org . - 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 .
