I see questions like this quite often when I'm teaching workshops, from people with all different kinds of camera-flash systems.
If you want to understand using a dedicated, auto-metering flash system like this, see Joe McNally's books, workshops and videos. They're based on Nikon equipment and their iTTL system, likely the best in the business, but the principles apply to any dedicated flash automation setup. Rick Sammon recently did a similar book based around the Canon E-TTL flash system, it's probably in the same ballpark. Those who prefer simpler, more basic flash use should look into the Strobist world for tutorials and ideas. http://strobist.blogspot.com/ I've been using flash illumination, for fill, main light, multi-light setups etc, since the 1970s. To me, all these dedicated autoflash systems are on the one hand a great convenience for some things and a huge handicap for other things. To me, understanding how they work and how to control lighting with them is often more work than understanding how to use a simple, basic, manual flash system. Even when I was shooting film, I preferred manual flash systems. With digital, it's such a piece of cake I don't understand the need for all the complexity of a dedicated autoflash system. Proper exposure is a combination of knowing what your intent is, a few simple things about the light sources you're using, and understanding how to manipulate the camera settings and the flash unit to produce the results desired. If the main light is the flash: - Aperture controls the focus zone. - ISO and exposure time @ an aperture setting control how much ambient light fill you get. - Distance and flash output control the intensity of the main light. If the main light is ambient and the flash is used for fill: - The rules above apply but you consider the ambient light as the main source and reduce flash illumination relative to it. When I do use TTL flash automation systems for fill flash, I find the only way to get consistent results with almost any camera and flash system is to: - Set camera to Manual exposure - Pick an ISO, aperture and exposure time to give appropriately correct main light exposure for the subject - Set the Flash EV-compensation control to work in the correct range, typically -2 to -1.3 EV is about right. This puts the burden of the flash exposure on the camera and flash unit, balancing against the ambient light setting which is fixed and manual. Using high speed sync options of the flash system is often called for if you're working in bright sunlight because you have a lot more flexibility on exposure time that way (not lmited to X-sync shutter time setting). You need to be sensitive to the limits of the flash automation system ... how much power does the flash unit have at most in the mode you're using, how *little* power can it be throttled back to on automatic, etc ... and adjust ISO settings, aperture setting, and distance to the flash to suit those limitations. (The only real difference when using auto-TTL metering when doing this and working the flash exposure by manual power settings is that the flash unit will automatically accommodate minor changes in subject reflectivity and distance, rather than you having to adjust the power output and position of the flash constantly.) It's not hard to do, and with a digital camera and immediate capability to evaluate what an exposure has done by going to review and looking at the histogram for the captures it makes the setup operation consistent and foolproof for any lighting situation. -- Godfrey godfreydigiorgi.posterous.com -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
