From: "John Mason" : Listers, I need some advice on flash compensation. : I want to experiment with flash photography, beginning : with fill flash. I want to lighten in shadows and : otherwise lift the veil of darkness, but I'd like the : use of the flash to be as subtle as possible. for it to be subtle there are a few simple things to consider, firstly the flash must just _fill_ th shadows, not overpower them. Light in nature tends to be dominant from one angle only and the worst fill flash mistake is to over illuminate the sudject with careless flash usage. in fact often a reflector will do a better job than any flash, but as flash is more convenient, it's often used as a replacement for a reflector. : Here's my plan for on-camera fill flash. Tell me : where I'm going wrong. : 2) Select manual mode. Meter the subject manually : and set exposure. : : 3) Dial in negative exposure compensation--say -1/2, : -1, and -1 1/2 or -1/3, -2/3, and -1 1/3--to back the : flash off. : : 4) Expect properly exposed images, with subject : brighter to varying degrees than background. no! you want to keep the exposure lower than the ambient light. An example. Sun in background is illuminating all and sundry - ISO100, exposure indicated is f16 @ 1/100th you want the flash to output an exposure indicated to be 11 1/2 on a flash meter. This means the subject will recieve a half a stop less light than the ambient light and it will look _natural_ it's much easier to work with guide numbers on a manual flash than using auto flashes for fill flash work too, as auto flashes can be tricked by specular highlights, dark or light subjects - any number of things into outputting too much or too little light and you will never know what went wrong with the shot if it fails! Lets say same shot as above and you have a flash with a GN of 32. GN=f no x distance. Since I'm in Oz and we're upside down we use metric, so a GN 32 divided by 11.5 = 2.7 so I'd position myself 2.7 meters from the subject and thump off the shot (with the appropriate lens to frame it of course) Lets say I can't manage that but I have 1/2 and 1/4 power settings and I've tested them in advance and found them accurate** I'd set the flash to 1/2 power (GN16) and back off to 1.4 meters from the subject. (**BIG assumption and often incorrect. Best thing to do is measure the power outputsa with a flash meter and write the actual GN's on the flash unit) the other cool thing about using a manual flash and the guide numbers is that you know what the distance is supposed to be so you prefocus to this distance and use your feet to position yourself at the right distance - better than autofocus! :-) : 1) Place flash on camera. Put small white card on : back side of flash; hold in place with rubber bands. : Tilt flash head up about 45 degrees. this is unnecessary and reduces the power output, it may also cause uneven light output if the card wiggles or something unexpected (a branch or whatever) intrudes to add more or less to the exposure. The light only needs to _fill_ the shot so it's quite OK to come from the front near the lens. No softening is really needed and the small amount offered by a white card is negligable. : 2) Set to manual mode. Meter the subject manually : and set exposure. yesssss! :-) : 4) Expect properly exposed images, with subject : slightly brighter than background. Hokay, you seem really keen to go this path ;-) Tell you what John, don't listen to me re under or over exposure relative to the natural lighting, try a series yourself to see what suits your shots. youo will find it easier to go manual with the ol' fl;ash though and use the GN's. Hope this helps k
