100 or 120 degree diffuser

[Pongo1998]

I have the ys-d1 strobes and I am confussed with what is the difference between the two diffusers? I mean other than 20 degrees. Is there a big difference between the two? I don't understand which one to use.

 

[danilocesar]

I'm not sure if it's what you expect to hear, but the difusers increses the coverage angle (80/100/120 for the YS-D1 afair) and reduces the power of the light.

Maybe you should read this: http://www.uwphotographyguide.com/underwater-photography-underwater-lighting-strobes

* I have two YS-D1 but I only use the 100 degrees difuser for WA shots. I shouldn't be used as reference

 

[mjh]

With the YS-D1 it goes like this...Without the strobe you get 80 degrees of coverage and a Guide Number 32. This is fine for macro, or say shark dives, in clear water where the creatures are a little farther out but you need some power. With the 100 degree diffuser you get a Guide Number of around 24. This is great for all around shooting. With the 120 degree diffuser you get a Guide Number of about 20. This is when you are shooting Wide Angle and getting really close with fisheye lenses or the like.

Hope that helps.