Some time ago I wrote my initial impressions on the Viewfinder Photography Speedlite Kit. If you read through to the end, I had then noted that the mini dish made the flash get the munchies for batteries. Back then, it was an observation, which got reinforced after some mid-flight out-of-juice issues and the limited power output I was getting from the mini beauty dish.
A week ago I finally ordered a Sekonic L-308S flash meter. Now, with an accurate measuring device in hand I had the means to setup a controlled test to evaluate the power consumption behavior of the Mini Beauty Dish.
The experiment consisted of fixing the flash and flashmeter to the working surface (my desk in this case). Then I’d simply put the meter in manual reading mode and trigger the flash. As for every experiment, you need a control scenario that gives you grounds for comparisons. My main concern with the beauty dish is the internal convex deflector, which seems to trap the light instead of reflecting it towards the metallic reflector surface. The test will compare the performance of the flash + reflector with and without the internal ‘deflector’.
It’s worth nothing that the bare flash and the flash+ dish reflector are almost equivalent as the speedlite already has a internal fresnel element to focus the light forward.
The control frame without the deflector in place gives a meter reading of f/22 +0.1 (speedlite at 1/16 power).
With the deflector in place, the same 1/16 power output from the flash results in a meter reading of f/2.8 +0.6 (in 3rd of stops that is aprox f/3.5)
Now, extend your fingers and start counting: f/16 -> f/11 -> f/8 -> f/5.6 -> f/4 -> f2.8. Wow you just used all your fingers, didn’t you!? Well, we need to count only a fraction of the last one, so that makes 4 fingers and a 1/3.
That is an outrageous 4+1/3 stops of light vanished from the exposure equation.
To put that into perspective, a 70cm Octa has a ‘power tax’ of 2+2/3 stops and you have a whooping light surface of 4060cm2. The mini beauty dish has a front area of 176cm2 and bear in mind what the deflector blocks most of it.
I know I’m living in Belgium, but a ‘power tax’ of 4+1/3 stops is way too much to afford. In the speedlite world, that translates in critically reduced working distances and shortened battery life.
What to do?
If you have bought one of these Viewfinder Photography Speedlite Kit, and want to use the mini beauty dish, there’re few things you can do to:
For soft light:
- Remove the reflector and put on the white snap-on diffusor: That will give you a small source of difussed light. Probably good for a close-up portrait.
- Replace the internal deflector by a diffusing surface, like a piece of white milk-ish plexi.
For hard light:
- The metallic reflector is useful to avoid flare from the flash. The flash effect will be as harsh as with a bare speedlite, but the spread of light is a bit more controlled. I used that technique for this image: Leen
- The reflector and honeycomb combination works quite well for further control of the light beam.
If for some reason you still want to use the internal deflector, put it inside-out. With the round surface facing the light source, light spreads outwards towards the reflector and you win 1 stop in performance. 3+1/3 stops instead of 4+1/3.
Question? Post them here below.
PS: Some additional test images: