On Apr 29, 2011, at 4:57 AM, AlunFoto wrote: > In the AF-540FGZ manual it says there is an absolute minimum usable > distance in P-TTL (0.7 m). I always thought that was because the flash > was unable to quench its output fast enough to operate at shorter > distances. I thought so because quenching the blink was how the old > TTL system worked. Then, today I took the flash off-camera and began > experimenting. To my surprise, the shots where the flash was closer > than 70 cm from the subject became underexposed, not overexposed. It > got worse the closer I held the flash. > > The only explanation I have come up with is that the power used for > preflash must be constant, and too strong to let the camera meter > accurately at distances shorter than 70 cm.
Very interesting. Have you tried putting some sort of a filter over the flash so that the preflash is that much weaker? > > Maybe this was obvious to everyone but me. So, eureka or d'oh? > > Jostein > > -- > http://www.alunfoto.no/galleri/ > http://alunfoto.blogspot.com > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- Larry Colen l...@red4est.com sent from i4est -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
