Paul C. Buff, Inc. Technical Forum

I'm wondering what the best way is to gel the large octa ?, i was thinking the internal baffle ? but was wondering if there is a more ingenious PCB way of doing it ?

That is one of the most popular ways. Another is to cut an X in the center, and poke the post (that serves like an umbrella shaft) through it, and hold it in place with the slider. Clips or gaff tape may be useful in keeping the edges in place.

Alternatively, 4 sheets of gel taped together and placed on the front would also work. This may be easier to seal all white light from leaking through.

This may help.

http://strobist.blogspot.com/2013/01/how-to-gelling-large-light-sources.html

Maybe you can modify the method he uses for the PLM speed ring for the "cage" at the back of the octa.

I measured out the inner baffle, cut out the CTO so it was smaller (covers the umbrella ribs all the way to reflective material.

Then i cut a hole in the middle where the shaft would go, reinforced it with gaff tape, cut another whole in the gaff, reinforced it again and boom, done.

Means the CTO won't rip with going on and off the shaft, it doesn't even really need gaffed to the reflective surface when cut properly, but some velcro might be a good move.