View Full Version : Balancing Ambient and Flash
Keltic Ice Man
4th May 2009, 10:58 AM
Often in the wedding forum there is a mention of the flash being unbalanced with the ambient light.
How do you go about balancing the lights?
4th May 2009, 11:01 AM
Good question and one I will be interested to keep an eye on for the answers.I do know that on Saturday at the wedding I was at Ray used his flash and kept setting the power levels on the flash to compliment the light that was there.
4th May 2009, 11:10 AM
Imagine you meter for a subject without your flash switched on.
If the light behind the subject is quite low then the subject will show quite bright in the final image.
Imagine your subject has a sunset behind them - the camera will meter for the bright light thus throwing your subject into darkness. Sometimes you want this to do silhouettes etc.
You will increase and decrease your flash to compensate for this - let the camera worry about the background and then you flash the subject to expose the whole scene correctly.
Keltic Ice Man
4th May 2009, 11:31 AM
Thanks Stemmy, but how do i know how much to light, is it trial and error or is there a black magic at work ?
4th May 2009, 11:39 AM
Its experience thats all - I can look at an image and guesstimate how many stops difference the light is on the background in relation to then foreground.
You could do it another way - as the subject to move and meter for the background - then ask the subject to come back and then zoom in on them to remove the background. compare the two and this will give you the stops difference.
You can then alter your flash accordingly.
4th May 2009, 11:55 AM
As Martin has said, unbalanced flash will mean that the light from the flash overpowers the ambient light in the scene, the idea is to balance the light from the flash so that it is balanced with the ambient light, making it difficult to know that flash has been used.
for example if you had your subject standing by a window with plenty of natural light, without a reflector or some balanced "fill" flash your subject will have shadows on the side away from the ambient light.
to balance the flash to blend in with the natural light you would reduce the flashes power until the light from the flash doesnt overpower the light from the window which will lift the shadows and without brightening the side lit by the window light
4th May 2009, 04:30 PM
Depending on your camera, use slow or rear curtain sync (I always rear curtain - another conversation) and matrix metering. Take a shot look at the pic on the LCD and compensate flash accordingly. On Nikons make sure use use flash compensation not camera exposure compensation because the later is a global setting which effects the flash as well :-)
PS Great picture Jason.
Keltic Ice Man
4th May 2009, 05:12 PM
Excellent example Jason, Many thanks.
Think I need to read around this quite a bit, as im often unhappy with my flash work
4th May 2009, 06:00 PM
here is a good rule of thumb. Leave the camera flash on ettl (or similar on your model):
bright sunlight behind subject or really bright day, full power flash.
cloudy with breaks of light, - 1 stop on the flash.
under cover or shade, - -2 stops on the flash.
Indoors in dim light set ISO to 800 (or so) lower shutter speed for the subject and shoot at the lens lowest f stop. This is a good starting point to balance indoor dark scenes and flash.
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