Change output of a flash

Charliedelta · Jun 4, 2013

I have an old flash where I cannot control the output (it only shoots at full power). Besides the obvious increasing the flash to subject distance, is there something a can put in front of the flash (like a softbox or something) to reduce the flash output?

Gavjenks · Jun 5, 2013

1) Yes, a softbox or whatever in front of it will somewhat decrease the output by absorbing a little light, scattering some away from your camera, and reflecting some back at the flash. Probably at least 1 stop for a large white softbox.

2) You could bounce it off the wall or ceiling. This often improves the look of flash anyway on the cheap, as well as decreasing its strength due to essentially doubling the range in most cases (+ scattering + absorption). It will as a rule of thumb decrease power by about two stops with a white ceiling or wall nearby. If you bounce off of a darker colored wall, then the drop in power could be very significant (several stops potentially), however if you bounce off of a non-white wall, your flash will pick up a color cast the same color as the wall. Gray and black walls are relatively rare.

3) You could trigger it remotely and then move it behind you so it's further from the subject. 40% further away = 1 stop weaker flash.

4) You could decrease your aperture. One stop smaller aperture = one stop effectively weaker flash.

tirediron · Jun 5, 2013

Or you could place a netural density filter in front of it (They're not just for lenses you know). Either by holding a regular circular/rectangular camera one, or a neutral density flash gel such as in this kit.

cgipson1 · Jun 5, 2013

you can buy diffusion material that is measured in stop or partial stop values.. and put one or multiple layers in front of your flash. Personally I would just buy a better flash.. not worth the hassle! And use that one for background lighting or something.

Professional diffusion materials are neutral in color (they don't change the color of the light!)

Tissues, paper towels, and other DIY type materials will often (usually) throw a color cast into the mix... which can be nearly impossible to correct for, even with a manual white balance!