Strobist Exercise 102-1-3 (Reflections off Glass)

There are 2 exercises here.

I will first light glass with Bright Field Lighting (Hunter/Fuqua in Light Science & Magic). I cut out a hole in a cardboard box, slightly smaller than an 8 1/2" x 11 piece of paper. That was going to be my opaque background. I would light the background w/ Nikon SB-80DX on remote, 1/16th power. I was supposed to frame the opening exactly, not less, not more. Easier said than done. First try was first mistake. I had the paper on the wrong side of the box, so the edge of the box was "blurry."

I changed it to the back, just 1/8" difference, but you need that for the edges of the glass to look black. Now I have everything okay, with the very white background (abt 1-2 stops greater than middle gray). I also found out my paper was pretty poor, as when I made it near middle gray, it showed lots of molting. Next time I should use a scoop with plastic.

My 1st image w/glass shows that I need more care in positioning the camera angle to exactly frame the opening (my opaque background). Note, the cardboard is actually brown, but the exposure makes it appear black. Nice black lines around the glass. I was amazing the technique actually works! Although the bottom third of the image is gray due to exposure, I did put supplemental lighting (not shown) that lights up that bottom to better match the top 2/3s of the image.








Just to make sure 2 glass can both have definition of black lines, here's the proof. The back glass is not in focus, but that was not the point; just wanted to make sure the black lines defining the glass was there. Notice the reduce exposure in back, showing the molting of the cheap COSTCO paper I bought:

However, I spent too long trying to figure out now to get a reflection on Light-Field Lighting. Of course I couldn't--the reflections couldn't be light on light. Next time try a dark object; would that work?

Now on the the 2nd half, Dark Field Lighting. I pulled out a very large sheet of translucent plexiglass, and taped a large cardboard rectangle to block the light. No change in exposure that recorded my first image of dark field lighting:

Why were reflections there? My D200 built-in flash was on 1/128 power, which was not enough to record with Light Field Lighting, but with black field lighting it reflect that small bit of flash. So I put on my Nikon infared light blocker, the SG-3R. I paid $12 for it, so why not use it? Worked like a charm, especially after moving up the black card to include most of the glass. There are other slight reflections from not having the room entire dark, but I was satisfied with this final picture, w/o reflections. I now know it is glass....

Now for the final act--to show reflection in the glass. Getting these angles of reflection was absolutely impossible. I just estimated it, and here are the 2 images I came up with, far & mid. The near didn't make anything but a glob of reflections.


Next time to work on:

1. Make better props, translucent panels and black cardboard. Use a scoop, for heavens sake.
2. Create a seamless bottom, all black. Do I need to use a glass table?
3. Better position the camera to get really black lines on glass for Bright-Field lighting.
4. Figure out whether a dark object on Bright-Field lighting will show up as a reflection. It should, so I should also try some sort of color diffusions sheet positions.
   
5. Figure out a way to measure possible diffusion sheet positions for lighting Black-field lighting reflections.

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