I want to finish up my thoughts about flash photography which I started in my previous post, so I hope you not so technical minded will have me excused one more time – even if it’s going to be less hardcore technical this time. I promise it will be a long time till next before I will do it again. So as to not make it completely worthless to have passed by, I have laid out a handful of pictures to show what you can achieve by using the little shoe mounted flash. I hope those of you who don’t care about technique at least will be able to enjoy those pictures.
Last time I gave the theory behind getting the most out of the flash – and did so by explaining how to use the camera in manual mode. Today I will continue with some thoughts about using flash in automatic mode. One should actually assume that it would be easier and faster – and to some extent it is, but at the same time I have found that it’s impossible to predict how the cameras «think». And unfortunately one camera «thinks» differently than another in automatic flash mode, and one brand seems to «thinks» differently than another. So when going automatic, it’s unavoidable with some trial and error first time out. Anyway the basic idea when going automatic is that the camera itself will do the necessary calculations, as soon as you have put in the ratio of exposure between available light and flash light. Remember the trick to get interesting flash pictures when using a shoe mounted (or handheld) flash is to combine available light with flash light.
On a basic level most cameras «think» that whatever exposure compensation you dial in on the camera will affect the whole exposure – the combined exposure of the two light sources that is, while exposure compensation dialled in on the flash itself will only affect the flash light. So to return to the two basic setups from my last posting: If you want to equally blend available light and flash light, you actually don’t do anything, because the camera will automatically take care of the mix and adjust the exposure – which means underexpose both so as to make the combination come out correctly. The only thing you need to do is make sure the exposure mode of the camera is not set to program, P, green, red or complete automatic mode – whatever you camera has available for you. This will only set the shutter speed to the sync speed for flash photography and thus result in those regular ugly flash photos with a washed out foreground and a completely black background. My advice is to set the mode to aperture priority which means you yourself set the aperture before taking a photo and the camera automatically takes care of shutter speed. Setting the camera to aperture priority mode makes sure your camera can adjust the exposure to any available light situations. If necessary it can use 1 second or it can use 1/1000 of a second when that is necessary. By the way don’t worry about long exposure time when using flash. The flash will anyway freezes the subject and whatever movement cause by the available light exposure will only add some interesting features to the picture.
One more thing: You need to make sure the camera’s focusing point is locked onto the subject in the front when the reading of the flash exposure and the focusing point is connected. Otherwise the amount of flash light on the subject will probably be way too much since the focusing point may be set on the background.
Now to the other set-up I mentioned last time; fill-in flash or using the flash to lighten up dark shadows. In automatic mode you set the flash to -2 or two exposure values down. That’s it, and the camera will supposedly take care of the rest. In another word, you use the exposure compensation on the flash to adjust the ration between available light and flash light, while the exposure compensation on the camera will affect the combined exposure. That is; if you want to make the combined exposure lighter or darker you use the exposure compensation on the camera. If you want to increase or decrease the amount of flash light relative to available light you use the exposure compensation on the flash.
What if you only have a point-and-shoot camera? Can you get interesting flash pictures with those cameras? Quite few actually have a so-called slow sync flash setting, which will do exactly what I have talked about here. You just don’t have equal amount of possibilities to adjust particularly the ratio of light between available and flash light.
One last point: If you use your camera in manual mode and use the built-in exposure meter, be aware of the fact that when you turn on the flash it will most likely adjust the readings to compensate for the added flash. So if you want to work manually, you need to meter the exposure of available light before switching on the flash.