vinmunoz wrote in post #18118399
thanks I will try that AV technique you have. Yah i got the BFT idea from him. I also bought one of his flash photography video.
been hearing many times about "the flash will freeze the motion" but i really don't understand how is it possible. any theories for that?
Flash duration is much faster than the SS, so if your subject is primarily exposed by the flash, it will stop the motion of your subject. The effectiveness of this depends on how much ambient light is exposing your subject. If you're using an EC of -2, then your subject is primarily exposed by the flash (ambient is underexposed), then you'll likely freeze motion. The direction of the light also matters....if you bounce directly behind you, then your subject will be hit straight on and there will be less ambient light exposing your subject and you'll get less blur. If you bounce at diagonal angles, you might get some blur in the shadows (areas of your subject exposed by ambient light).
On that note...using a mixture of ambient light and a bounced speedlight to expose a shot is a similar mind-set to studio lighting...bounced flash is your 'key light' and the ambient is your 'fill'. Since the camera exposes the ambient, and the flash exposes the subject, if you trust EC and ETTL (I do), then adjusting the EC is the way you manipulate the lighting ratio. As such, adjusting the EC is how you control the prominence of the shadows/contrast on your subjects. Lower EC = more prominent shadows/contrast...also more isolation from the background.
Last note...mixing ambient light and bounced flash to expose a shot means you need to use flash gels to avoid getting color casts. I've be meaning to get that expodisc you use, as that should really simplify the process of geling a light to the right temperature to match the ambient.