Discoloration in the eye is due to several years of drying in this old specimen.
The setup for this shot was pretty simple: just a 4X objective (Nikon CFI BE) stuck on the end of a 55-200 mm telephoto lens on a Canon T1i camera. Focus stepping by AF motor control, using the CamRanger. (I couldn't resist assembling a stack of "supporting documentation".)
Here's the entire frame. There is some vignetting because I zoomed out the telephoto in order to slightly widen the field. EXIF data reports 155mm, implying about 3X actual magnification.
Focus stepping is 71 frames at the smallest increment of the CamRanger. The small increment is required despite effective f/15 because the telephoto is front-focusing. The smallest increments of focus are very small when the telephoto is used by itself, but they advance the front of the lens by an amount that is significant compared to the roughly 50 micron DOF of an NA 0.1 objective.
The CamRanger currently only allows 50 frames per stack, so I just ran one stack of 50, then immediately another stack to get the rest of the required frames. The second stack ran into the infinity focus stop of the lens and produced a bunch of identical frames, so I truncated the stack before processing it.
ISO 100, 1/8 second. The CamRanger requires that the camera be in live view mode, so with Canon cameras that automatically implies EFSC.
Zerene Stacker PMax, no retouching. The stereo is +-2%.
BTW, I went looking for an SEM photo of the eye structure, but all I could find was a closeup of a few ommatidia and the bases of some hairs. If somebody can find one comparable to the overview shown here, I would appreciate the link. Thanks!
--Rik
