Hi all, >From NK Guy's guide for EOS Flash (http://photonotes.org/articles/eos-flash/ ), Part II, Auto Fill reduction:
"Also called "automatic reduction of flash output" in some Canon documentation. Canon EOS cameras automatically use regular flash exposure with no compensation when ambient light levels are low - 10 EV or lower. However, when ambient light levels are brighter - 13 EV or higher - the camera will switch to fill flash mode and reduce the flash unit's output level. It does so in TTL mode by dropping flash output by 1.5 stops. Between 10 and 13 EV the camera will smoothly lower the flash unit's output by half a stop for each EV." So my question is: How much exposure/light is 10 or 13 EV? I want to know so if I'm using my flash outdoors, I can understand what the camera is deciding and maybe override it. >From a table I don't have the link right now, it says 10 EV are at 125 f2.8 (and equivalent exposures) and 13 EV at 1000 f2.8 (and equivalent exposures) but is this independent of the film used? The site doesn't mention any specific ASA for the table but obviously 125 f2.8 is going to have different results in ASA 100 than in ASA 400 film. I guess the table is for ASA 100 but that's just a guess, I'll like to confirm this. Does the EV changes linearly as ASA changes? I mean, if for ASA 100, 125 f2.8 produces 10 EV, for ASA 400, 10 EV would be 500 f2.8? Lastly, does this "Auto Fill Reduction" algorithm works on any mode (P, Tv, Av, M) or only on P? The guide is not clear about that (see EOS Flash Photography Confusion, further down the chapter). Cheers, Carlos ___________________________________________________ Yahoo! Sorteos - http://loteria.yahoo.es Juega a la Loter�a Primitiva sin salir de casa * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
