The Origami Exposure Pyramid

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,742
Having lost maybe a dozen ColorChecker Passports due to excessive sunlight, dirt, dropping down mine shafts, losing on sets, aging, dye color shifts, etc. I decided I needed something cheaper to set up the "Expose to the Right" exposure thing.

Using the E-M1 Mark II's red "Over-exposure blinky" I came up with a home-made means to make sure I could fully expose to the right. It involves some bright white (100 brightness) typing paper (8.5"x11") and a reasonable printer to print the image below (Print full-scale to the paper.). Image is a faint green and prints in the lower right corner.

The paper is folded up per this video:


You end up with a pyramid with the image on one side. Once folded into the Origami pyramid, it's also slanted at an angle that is good for the daytime sun to light and somewhat resistant to wind verses an upright card. All you need to do is start the camera's exposure with a gross over-exposure so you see the entire face of the pyramid in red blinkies, and then turn the settings until the red over-exposure blinkies disappear on the pyramid's face and make the shot.

Folding the paper per the video requires you to start folding with the green image facing down and to the right (landscape position), and then start folding it upwards per the video. If done right, the image will be on the outside of one of the pyramid faces. I've folded enough of them and it takes me about 3-4 minutes to make one.

I found the faint green color seems to affect the red over-exposure blinky more than the blue and red ones I've made, probably mid-spectrum and maybe the two greens in the Bayer cells too. A darker green doesn't provide the fine exposure tuning resolution, so a fainter green it is.

I set the Histogram number to 254 to make sure I can get the most range out of the image. Lowering the Histogram sensitivity from 255 to 245 also compresses the dynamic range of the image by almost 2/3-1 stop per my experimenting in RAW Digger. No need to lose shadow detail by going that low in the histogram settings, so keep it up to around 254.

Aside, RAW Digger shows there is still detail when the red-to-white blinky transition happens on the pyramid, but clicking one more third of a stop guarantees you are within the Olympus clipping range. Some software re-images differently (and Olympus is a bit conservative there, imho.). Example: I was seeing the red/white happening at 1/400 second and RAW Digger showed I still had usable detail in the RAW image file highlights, but Olympus Workspace didn't see it and liked 1/500 better.

Might be a nice club event or a class project.

Shown is a screenshot of the red over-exposure blinkies off the E-M1 Mark II LCD screen. Needs one more turn of the shutter or aperture (towards under-exposure) to get rid off them and be set right.

Pyramid-01.jpg
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This is the image to print on 8.5 x 11 inch bright white copy paper (100 Brightness) to make the pyramid in the video above.

Pyramid-Green-RGB 200-255-200.jpg
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Have fun!
 
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