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Old February 8th, 2013, 12:04 PM   #1
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Single/Double scrim units to stops controversy

I'm trying to figure out what Lowel DP scrims I have in a pile that I bought used. I have been taking measurements by pointing my lowel DP at the white walls of my bathroom and reading with my 60d camera meter.

It appears that I have a couple of Full scrims that reduce light by about 3/4 stop. I'm having trouble deciding whether this is considered a single or double. According to this thread:

Scriming lights [Archive] - DVXuser.com -- The online community for filmmaking

Single= 1/2 stop
Double=1 stops

But at least on B&H's site, Lowel seems to be using a different standard: Single=1 stop
Lowel 5-1/4" Full Scrim for DP Light D2-54 B&H Photo Video
http://www.lowel.com/download/LowelD...sWeb_05_10.pdf

So I'm going to call this a Full Single 1 stop scrim and assume my measurement was just a little low.

I also have some half scrims, one of which seems to be made with the same size screen as the Full one, so I am going to assume they are lowel Single(1 stop) and lowel Double (2 stop) even though my actual measurements were that the Half Single only reduced the light 2/3 stops and the Half Double reduced it 1 stop (Hmm, does that mean Arri is using standard scrim sizes after all? Edit: no, these numbers are probably lower than those of the Full size, because light from the open half spills into the other half).

This is all very confusing... if Arri uses the standard Single=1/2stop, Double=1stop then I have:

Full Single: measures 3/4 stop actual.
Half Single:measures 2/3 stop actual.
Half Double: measures 1 stop actual.

Does that sound right? I'm going to get out the Sharpie and mark these things and don't want to label a Double as a Single or vice versa. I've already marked the stops on them, which is the most important part.

Oh, and just to throw out another wrinkle, the safety scrim that supposedly passes 70% according to lowel measures 1/3 stop, which is almost the half stop that some consider Single, even though it's supposed to just be for safety.

Last edited by Tom Morrow; February 8th, 2013 at 02:07 PM.
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Old February 8th, 2013, 12:44 PM   #2
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Re: Single/Double scrim units to stops controversy

Okay, so I decided I would compare with some Arri scrims that I have. The Arri ones are color coded green for Single, Red for Double so I know what I''ve got. Here is the light measurements I came up with:

+0 stops Nothing on light.
-1/3 stops Arri Full Single Only
-1/3 stops Lowel safety Screen (70% rated)
-2/3 stops Arri Full Double Only
-1 Lowel Full "Single" Only

Based on this analysis, I'm going to stipulate that Arri uses Single=1/2 stop, Double=1 stop, while Lowel uses a different system, where Single=1 stop.
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Old February 8th, 2013, 01:09 PM   #3
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Re: Single/Double scrim units to stops controversy

Okay, so I'm now realizing that Lowel doesn't seem to use the word "Double" with their scrims; they only have single scrims. Maybe that's part of why they are on a different standard. I'm not sure how I ended up with two different screen widths of Lowel Half, when the only non-graduated half scrim in Lowel's catalog is the D2-55, but I'm going to label them Lowel Single and Lowel Double , and write "equiv to ARRI Double" and "equiv to Arri double doubled" on them respectively.
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