Paul C. Buff, Inc. Technical Forum

I'm trying to get a better understanding about the need of the critical focusing on the PLM. Also, how will I know that is needed? Using the speed ring to mount the PLM, if the PLM is locked into it's standard position (center hole) on the rod, what is the positioning range of the PLM to the subject? Say that I normally place my strobe about 10' away from the subject, should I be adjusting the PLM travel on the rod. Thanks.

Which PLM do you have? The extreme silver would be the one to be most concerned about, white cannot focus, and soft silver can technically change focus, but little difference will be found.

Sorry for not including that info. I have the 64" soft silver. I have plans to get the 64" extreme silver.

In a quick test, at 10' I did need to adjust the 64" umbrella (out) for maximum focus. At 14' this is not needed. However, maximum focus may or may not be the needed result.The more focused, the smaller the area covered. You can aim the light//PLM at a blank wall and see how the pattern will fall using the model lamp. However, you will want to take a photo to verify the pattern as the model lamp will not be on the exact same plane as the flash tube (except on Einstein, where the two match). Also, most people do not shoot blank walls, but usually have a 3D subject. In this case, any minor pattern disruption from "defocusing" may be preferable (if not completely un-noticable) in favor of sufficient spread of light.