Using an ND filter with flash

[zarekr]

I've come across a lot of discussions where people get confused about how an ND filter can help when used with flash. I like to think of them as sunglasses for the lens - not only does the filter dim the ambient light but it will do the same if you try to light your subject with flash, and so if you do end up using an ND filter to cut the ambient light (as opposed to using a smaller aperture which puts more in focus) you need to use a more powerful light, like the Elinchrom Quadra or a bunch of speedlights together.

This is the sort of image I'm talking about:



I wrote this up in a little more depth here, and I'd love your feedback on it.