Do I need the deflector plate when using a Westcott Rapid Box Octa with the diffusion front on?

Question

I’m considering adding a Westcott Rapid Box 26" Octa to my setup. Many reviews say the optional internal deflector plate is essential, but it’s often described as being for beauty-dish style use without the front diffusion panel.

If I plan to use the Octa mainly as a soft light with the white diffusion cover installed, does the deflector plate still make a meaningful difference? I’m already happy with the evenness from my Rapid Box Strip without one, so I’m wondering whether the Octa’s larger size/shape makes the plate more important, especially with a speedlight.

user1943 · Accepted Answer

Quick Answer

You don't need it, and possibly don't even want it. You do want a Sto-Fen or similar push-on diffuser, though.

Details

I know Stan knows what he's talking about, but I had some downtime this afternoon and my normal models are off watching the new Muppet movie with friends, so I decided to experiment a bit.

The Setup

Westcott Rapid Box 26" Octa with Cheetah Light V850 (radio trigger hotshoe flash). I dialed the flash power back to ¹⁄₁₂₈th, zoomed it to its widest setting, and selected a relatively narrow aperture and low ISO.

I took three test shots, one with the flash unmodified, one with the wide angle diffuser pulled down, and one with a Sto-Fen push-on diffuser. (See my previous test with the Rapid Box 10"×24" Strip .) Then, I repeated this with the defector plate in place.

The Results

Without deflector plate With deflector plate

As before, the bare flash clearly doesn't produce enough spread. Unlike the previous test with the smaller rectangular box, there is a clear advantage to using the push-on diffuser over the wide-angle panel. The extra internal diffusion is particularly interesting in the last test where the plate ends up with an... umbra and penumbra, I guess.

Conclusion

The plate casts a considerable shadow. It might be useful in some cases, but for most even light, use without the plate but make sure to use a push-on diffuser.

Bonus Shots

Here's a direct shot without the front diffusion material, in "beauty dish" configuration. (Push-on diffuser in use; it makes this better too.) Kind of an interestingly-distint spider pattern:

beauty dish

And, that pattern is actually fairly clear in catchlights, which some people might not find a nice as a pure, clean circle. If that's a concern, using the plate with the front diffusion material might be preferred (although then, of course, you're not really getting the harder beauty-dish look).

eye with catchlight