My last post featured white box photography of tobacco hornworms (Manduca sexta). I used the same technique that I described in previous posts (see: How to: white box photography of Macleay’s spectre stick insects) to produce nicely lit pictures of the animals on a pure white background. I also noted that I had also experimented with using a white box to produced pictures of these caterpillars with a more natural background. Here are some results from that experimentation.
The goal was to illuminate the caterpillar with light reflected from the white foam core sides, top and bottom, but with a pure green background. I set up my white box in the same was as I have done previously, with two changes: I replaced the back panel of the white box with a section of green foam core; and I put the caterpillar specimen on a short branch that was stuck in a jar of sand instead of on the white floor.
The photo above shows the first photo I took with this technique. The lighting is nice, but there were two (relatively minor) problems:
- The green background reflected some light onto the white panels and gave the photo a very slight greenish colour cast.
- Even though it is not in focus, the texture of the green paper covering of the foam core can still be seen in the background.
The colour cast was easily fixed with a simple adjustment with Photoshop. The background was a slightly different matter. In the future I can consider different options for producing a more natural or at least less obviously unnatural background:
- I could construct a white box that was deeper, to move the background further back and more out of focus.
- I could use a background material that had less obvious texture.
- I could use a background material that had MORE texture, but that also that appeared more natural.
In the meantime, however, I wanted to improve the pictures I already had. The first thing I tried was as follows:
- I opened the original photo with Photoshop Elements 8.0 andselected the “Magic Wand tool” on the left-hand side, set the “Tolerance” to 20, and selected “anti-alias” and “Contiguous”.
- I then clicked on the green background in a few places until all the background was selected (but not the caterpillar or stick).
- I then clicked on the “Filter” menu, chose “Blur” and then “Average” and clicked “OK”.
The result is below.
As you can see the texture is gone, leaving a pure, smooth green background. This is definitely a better image. But I wasn’t sure if the background was actually too smooth. So I decided to try and create a background that was something of a compromise between the two photos, as follows:
- I opened the original photo with Photoshop Elements 8.0 and again used the “Magic Wand tool” to select the background.
- I then clicked on the “Filter” menu, chose “Blur” and then “Surface Blur”.
- I set the “Radius” to 32 pixels, and the “Threshold “ to 24 levels and clicked “OK”. To be honest, adjusting the “Threshold” didn’t seem to make much difference.
The result is below. Now the background still has some texture, but it appears less distinct and (maybe) more natural.
Of the three versions, I tend to prefer the third—although I’m not completely sure…I do like the second image too. If you have an opinion, I’d love to hear it.
I’ve added one more picture below, taken in exactly the same way, and with the background edited using the “Surface Blur” option.
The technical stuff:
Camera: Olympus E-620 digital SLR
Lens: Zuiko 35mm macro
Settings: manual exposure (F16 @ 1/125 sec)
Lighting: Vivitar 283 flash and VP-1 Vari-power adapter (1/8 power)