Paul C. Buff, Inc. Technical Forum

Parabolic Light Modifiers come in three sizes, 51", 64" and 86", measured tip to tip across the top arc. What are the depths and diameters of the PLMs?

Closed diameter is about 2". Closed length is about 1/2 the specified size, IE 86" is about 43".

That information isn't helpful to me.
I have a cramped space. I'd like to know the open diameter of the umbrellas so I can better judge their sizes when they are open.

@spectru - You're joking, right?
There are many images of PLMs in use, try a simple Google Image search "pcb plm", "paul buff plm" or "buff plm". These will provide a visual reference to their size.

The 86" PLM is more then 6', but less then 6'6". The depth is between 12" and 24" if I remember correctly. I haven't used mine in about a year (been shooting table-top), so that is as close as I can get. Hope this helps.

I don't know why most manufactures fail to provide this info, it's not just PCB.

Average of tip to tip distance and valley to valley distance on the 86 inch is 74 inches. They follow the same general rule as conventional umbrellas, despite the deeper But I've never tried to measure the depth.

It's weird, considering the difference in shape between a PLM and a more conventional umbrella, that the both follow the same rule: front diameter is 85% of the bow length.

While the PLM V2 looks a lot like a regular umbrella, the shape of the fabric is not the same. I have done at least 50 vector drawings and subsequent samples to achieve the exact arc needed to provide the smooth focused pattern produced by the Silver Version (arc shape is not very important for white versions.) The 16 rib design provides much more output and more perfect patterns than conventional 8 rib general purpose umbrellas, as well as nearly circular catchlights.

All knock off versions, such as Wescott and others copied PLM V1, which isn't shaped nearly as precisely as our V2, and doesn't provide the on axis speedring mount. Ironically they are more expensive. Wescott and other knock off white versions we have measured also use fabrics that fluoresce and produce very blue results . . . up to +1000°K color shift.

Customer service can give you the exact dimensions . . . the 86" version is about 73" from tip to tip across the face and about 20" deep when opened.

51-inch PLMv.2 = 51 inches across the outside top of the open umbrella, 43.75 inches in diameter (tip to tip, straight across the face), and 27 inches collapsed

64-inch PLMv.2 = 64 inches across the outside top of the open umbrella, 54 inches in diameter (tip to tip, straight across the face), and 33.5 inches collapsed

86-inch PLMv.2 = 86 inches across the outside top of the open umbrella, 73 inches in diameter (tip to tip, straight across the face), and 44 inches collapsed

Thank you very much. I appreciate the information.

Tip of the PLMs to faceplate/speedring plane is 21, 16, and 13 inches, respectively (give or take an inch).