I'm making a DIY Beauty Dish - a few Q's first

[doubledragon]

I am in the process of making a DIY beauty dish like the ones found on this site and the strobist blog. I have a few tech questions before I start...

1) should I paint the inside flat white or silver? I have a large popcorn bowl, about 14" diameter, which has a translucent lid that I may also use as a diffuser. I'm planning to paint the inside silver for a harder light source, then add the diffuser if I want a softer source - is that a good idea?

2) Many people have decided to use a convex mirror, like the ones found in auto supply stores, to bounce light to the outside of the bowl.. I was wondering if that is the most efficient way to bounce the light, as it seems that much of the light would bounce back into the flash head. I have been thinking of a cone shaped reflector, instead of the typical convex mirror, which I could fabricate out of cardboard or foamcore, then paint silver or cover with reflective tape. Would this design spread more of the light to the outer bowl ?

thanks!

[gonzogolf]

I think I would go with white as I'm not certain that silver paint is any more reflective than the white in terms of efficiency. Commercial beauty dishes are metal and polished or textured to get a particular effect. Also I think silver if it did actually improve efficiency would accentuate any hotspots you get, and you will get them with a homemade dish. But honestly having built one when they first came out, a small beauty dish for a speedlite is a fun project, the results are not all that great in my opinion.

[Rock31]

If you go with silver paint be careful, it can take a VERY long time to completely dry.

[CBokeh]

I've been wanting to make a beauty dish as well, but I've been too busy. Here are my thoughts. The silver will be more efficient in stransmitting light than the white, but the level of efficiency is based upon the level of reflectivity. The more mirror-like that the surface is (as opposed to silver color), the more efficient your BD will be. The downside is the light will be more specular with a silver reflecter, which some people dislike. However, the fact that you plan to use the lid as a secondary form of diffusion will compensate for the additional specularity that comes with silver lining.

Maybe my understanding is faulty, but think about it, you never see softboxes with white interiors, because manufacturers want the most light output to pass through their diffusers because the diffusion material is going to eat up light itself.

My feeling is, that if you build a white interior with the intent to use the lid as diffuser, you will see minimal light output from your dish. If you don't plan to use the lid, go with white. You could make the dish with white interior and if you don't like the output, you could add silver over the white paint later.

[gonzogolf]

I just picked up on your suggestion that you would use the lid as a diffusuion panel. A dish this size powered by a speedlite isnt going to support another level of diffusion, let alone one as thick as a lid. You might get it work with a thin cloth face, but if you want a softbox why go with a beauty dish design in the first place?