Thursday, December 30, 2010

Step-By-Step Example of Balancing Ambient with Bounce Flash

One of our readers, mshafik, is a very passionate advocate of Neil van Niekerk's bounce flash techniques.  In this guest post, he goes through the process of how to balance ambient with bounce flash, combining manual exposure with TTL flash.

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Hello everyone, this is my second guest post on this blog (thanks to Mic), if you haven’t seen the first one, you can find it here.

If you have read my first post then you know that I am fascinated by the use of on camera bounce flash, I actually believe it is the best invention after bread. I was introduced to this type of lighting by Neil Van Niekerk on his excellent Tangents blog (which has been recently indexed).

This post will be a quick example on the procedure I go through when setting my camera to use bounce flash, if you don’t know about bounce flash and balancing the ambient and flash, I would really recommend you to read Neil’s Tangents blog. I will assume that the reader is familiar with these techniques.

I had a recent revelation with my Canon system; I have always thought that using the manual mode on the camera meant that my flash had to be on manual as well. I was wrong, and I’m happy for that, I discovered that I can use my camera on manual mode with the flash on ETTL, and no matter what my exposure settings are the flash will try and expose correctly for my subject.

When I usually take any shot, I try to go for the lowest ISO possible to decrease the noise as much as possible (I am a pixel peeper by the way, and never print any pictures), so by considering this I started out with ISO 200. In the shot below, we were at night with some lamp posts and a pool in the background and I wanted these to be visible. I was using the 50mm f/1.8 II lens, and I am only comfortable at f/2.2 or smaller, I rarely use larger apertures due to focusing errors and I need some depth of field to get my subjects in focus. So I started with f/2.8 which will give me enough DoF. Finally for the shutter speed; using the 1/ (crop factor x focal length rule) I should have used 1/ (1.6x50) = 1/80 s, but I am comfortable shooting my 50mm at 1/60 without motion blur, so this where the shutter speed came from. I know the flash would have frozen the motion of my subjects, but I didn’t want any motion blur whatsoever.


I knew I had to increase the exposure by at least two stops to get something remotely visible, and since I wasn’t ready to sacrifice the aperture yet or the shutter speed, I bumped up the ISO to 800.

An important note here, never ever use your camera’s LCD for judging the exposure, in most cameras the LCD will show you a bright and overly saturated colorful image which doesn’t reflect your real exposure, use the histogram, it is accurate and will tell you lots of things the LCD doesn’t.


Better looking but not there yet, time to open up the aperture a bit. I went for f/2.2 which I consider is safe enough, two thirds of a stop increase in exposure.



Now the grass looks better, so for the final adjustment I increased the ISO to 1600 (practically noiseless at web viewing sizes) and closed the aperture one third of a stop, thus effectively increasing the exposure above the last image by two thirds of a stop.



That’s it, if you look at the EXIF for the above images, you will find that the time taken between the first image and the last one is just 25 seconds!



Now that I had the background I wanted; it was time to expose for my subjects, this is the easy part, I had a huge glass panel behind my back so I pointed my on camera flash over my right shoulder (effectively creating a light source on the top left of my subjects) and put the flash in ETTL mode. From experience; I know that my flash usually requires +2/3 or +1 flash exposure compensation, so I had that set from the beginning. And these are the resulting pictures.








They’re not particularly great shots, but I think it is a good example of the thought process, and as Neil demonstrated in his “Give me the f-stop” tutorial, the exact shutter speed & aperture settings are not the important part, it’s the thought process that results in a certain exposure.



If you consider normal options for taking this type of shot (without using off camera lighting which equals more heavy equipment to lug around) you’d either have to resort to extremely low shutter speeds (= blur), extremely high ISO (= noise) or direct flash which will most probably look bad and will not expose for the background.



If I had a point and shoot I would have opted for something called “slow sync” mode in which the camera uses a slow shutter speed to expose for the background and direct flash to expose for your subjects given that they stay still long enough.



I hope that was of any benefit to you, and please use the comments if you have any questions.