Friday, 6 April 2012

Diffusion & Bounce Rag Tests


Thanks to our friends at Panalux fellow Cinematographer Ed Moore (www.edmooredop.com) and I spent a day testing various permutations of Diffusion and Bounce materials and we’ve posted the results for all to see.

The basic principle was to be able to compare and contrast what the individual diffusion sources were doing to a single light source when pushed through them and/or bounced through them.  We were primarily interested in seeing how soft the light would become, how that would affect the shadows, how the light would wrap around an actors face, how quickly the light began to fall off and what kind of eye light it would catch. It was also interesting to note how much light was or wasn't lost with certain rags.

While we wanted the tests to be consistent they were not meant to be the most scientifically accurate lighting tests of all time so please take them as they were intended, which is as a useful reference for all Cinematographers and Gaffers to pinpoint what materials might best suit a particular project/lighting style.

All the images were shot in raw on the 5DMkII with the same shutter, ISO and aperture as the video. The stills were brought into Capture One and the exposure was tweaked until the same point on the 18% grey card read as an average of 118 over the RGB channels in sRGB colour space. This means the exposures should match throughout. A white balance was made on the test shot with the 10K direct with no diffusion and that was applied to all the shots. Any colour variance you see is the result of the diffusion's in use. The images were then reduced in size and the larger crop of the model's face was then re-added from the original high resolution file.

At the beginning of the “Direct” tests our single source, a 10K Fresnel, was placed approx 19 feet from the model, as a ¾ frontal key, at her approx eye-height. Our 8x8 frame was placed 8ft from the model and kept in an upright position. The Fresnel was spotted on the model and then flooded to fill the diffusion frame. As a base measurement the frame was removed and the light measured as a direct, undiffused source, with the Fresnel lens kept in the same medium flood position. For the rest of the tests the only factor that was changed was the type of diffusion within the frame.




At the beginning of the “Bounced” tests a second 8x8 frame was placed approx 3 feet behind the first frame in an open ended “book light” position with the 10K pushing in from one side. The “Bounce” source was primarily kept as an Ultrabounce but was switched to unbleached Muslin for one test, and unbleached muslin with an ultrabounce backing for another test, as noted.





As a final bonus test we compared a simple Poly bounce using a 5K bounced off of the white side and then the black side of a piece of 8 x 4 Poly at roughly 10 feet from the model and in a similar ¾ frontal key. The ASA for these two shots was raised to 1280asa to allow for the smaller amount of light from the black Poly bounce source. These final two tests were just meant as a comparison to each other and were NOT intended to be compared to the rest of the tests.

In all cases we kept a 2K Fresnel, down all the way on a dimmer, behind the model specifically to throw a comparison shadow on the White Poly behind her. The variance in brightness is due to the variance in our T-stop on each shot.


The results are available to watch both as Stills and HD video at the links below. I would Highly recommend you view both.


To view the results as HD video please visit https://vimeo.com/39856572


To View the results as high resolution stills please visit http://edmooredop.com/ragstest/


Both the Still images and Video look best when viewed in Safari and/or Firefox.

1 comment:

Ari said...

I've always wanted to do just this, so thank you! You guys rock.