In shooting the pectinate grooming spurs (here and here), I ran into a small problem (pardon the pun) in getting things properly aligned to photograph. The range of good viewing angles is pretty narrow, and in addition the spur and the tarsus are independently hinged to the tibia. Hence the problem: how to properly position all these parts and keep them positioned for long enough to shoot a stack.
In fresh specimens, the joints are quite flexible and prone to shift at the slightest provocation, or even with no provocation at all over the several minutes needed to shoot a high resolution stack. On the other hand, drying a specimen takes hours, it's liable to change position as it dries, and after it dries, it's very fragile. What to do, what do to?
Here's what I came up with.
The black pin is an entomological "minuten pin", dimensions roughly 0.4" long by 0.006" diameter (0.15 mm). The clear fiber is a single component strand separated from a piece of dental floss, diameter about 0.018 mm.
To assemble this contraption, I clipped off a leg in the middle of the femur, ran the minuten pin through the remaining half of the femur and out the knee, played with the dental floss until everything was where I wanted it, then fastened everything together with a tiny drop of superglue around the base of the femur.
As shown here, the pin is stuck into a piece of balsa wood, which in turn is fastened to a ball head (not shown). Reorienting the ball head and/or repositioning the pin in the balsa allows to get the correct viewing angle, and the pin and floss are out of the way for almost any possible angle. A piece of "gray" paper from an inkjet printer provides a neutral background -- as long as it's sufficiently OOF that you don't see the ink dots!
BTW, this pair of photos also nicely illustrates the perils of diffraction. The left image at a marked f/2.8 (effective f/9) has very limited DOF but is quite sharp in the focus plane. (Notice the glue joint and the grooming spur.) The right image, at f/22 (effective f/72) is noticeably fuzzy even when displaying almost a full frame at this 800-pixels web resolution.
Hope you find this interesting!
--Rik
