I have noticed that mine seems to expose differently depending on aperture - from a distance of about ten feet, I used the FA* 24 f/2 and shot at a painting in my bedroom. The smaller apertures showed a marked difference in exposure as compared to the bigger ones. This is using the AF500FTZ.
I rarely use flash, so I did not follow up on this much, except to form the impression that the firmware is probably defective. I did send a comment/complaint to Pentax Cnaada, with so far zero response. Quoting Bruce Dayton <[EMAIL PROTECTED]>: > Hello Heiko, > > Thanks for the information. Certainly something for me to check out. > My own observations are thus: > AF360FGZ seems to slighly underexpose - sometimes when vertical > shooting with flash mounted in hotshoe it underexposes by quite a bit. > AF400T seems to overexpose by at least a stop. > > These are with ISO set to 200. I'll have to try 400 and see what > happens. > > Again, thanks for the info. > > Bruce > > > > Tuesday, January 6, 2004, 2:32:00 AM, you wrote: > > HH> Hi Bruce, > > HH> on 05 Jan 04 you wrote in pentax.list: > > >>Certainly an area that I am most interested in. I am not shooting > >>with the AF500FTZ. I have the AF360FGZ and 2 AF400T's and 1 AF280T. > >>Could you be a bit more specific about what your results are like? > > HH> There's a German thread on incorrect flash exposures at > HH> http://www.digitalfotonetz.de/phpBB2/viewtopic.php?t=4997&highlight= > > HH> A source at Pentax Germany has explained that there exists a problem > HH> with the TTL-metering (I only repeat some statements of the mentioned > HH> link): The TTL-sensor measures the light that is reflected from the > HH> CCD's surface. But it seemes, that the reflection of the CCD differs > HH> depending on the chosen ISO setting. The exposure will be correct only > HH> at ISO400 as the development and testing of the TTL-measurement was > HH> apparently made at ISO400, only. > > HH> At ISO settings below 400 the camera will under-expose, at setting above > HH> 400 it will over-expose. > > HH> This problem can probably not be solved by a firmware update as there is > HH> no upgradeble TTL-software but some kind of hardware solution. The > HH> problem does not exist if you use P-TTL. > > HH> I didn't try that myself (although I have an AF500FTZ I'm not a great > HH> flash user), but maybe this informations brings some light into the > HH> flash behaviour of the *istD. > > > HH> Cheers, Heiko > > > ------------------------------------------------- This mail sent through IMP: http://horde.org/imp/
