Lighting 102 - 3.2: More On the Crosslight Thing
I want to revisit a few key things that you have to know to pull the technique off, and then Andrew is going to come to the front of the class to demonstrate. And besides, given that this went up on Thursday instead of Tuesday I am not going to be one of those hard-ass teachers and make you pull a quick turn to the next exercise.
(More after the jump.)
First, understand that with the ambient portion of your exposure your camera defines your upper limit -- i.e., how dark you can make the ambient. Set to the lowest ISO, the best you can do for darkening your ambient environment is to shoot at your max sync speed at the lowest aperture on your lens (i.e., likely f/16, /22, or /32).
You can get around this in a very clunky way with a neutral density filter, but it knocks down the flash, too. So your maximum lighting distance will stay the same.
Remember that this is built on a chosen ambient exposure that lets the shadows fall where they may, so you can light them back up with your flash. So you are limited to your sync speed for the ambient portion of the exposure, too.
Your working aperture, which will now be what determines your ambient exposure level, will also determine how far away you can stick your flash and still effectively light your subject.
In effect, the higher your max synch speed the farther away you can stick your flash and still pull the effect off. The lower your max synch speed, the closer your flash needs to be (not good for big group shots, obviously.)
If you have two flashes, you can gang them up with a Brewer Bracket or some ball bungees. That will give you double the light, which will amount to one more stop. This buys you more working distance on the flash and/or a darker ambient environment.
Strobist reader Andrew, who publishes www.meejahor.com, was nice enough to stick his process photos up as a series in this comment in the discussion thread.
Definitely check it out of you are having any trouble. He ran into a flash power issue and had to do a workaround in the form of opening up the sky one stop. Not his preference for the photo, but it makes it a much more illustrative example.
He has the process pix embedded in the comment, but the URLs are locked. (We were just going to borrow them, Andrew.) So you will have to click over to read about it.
Thanks for the helpful series and notes, Andrew.