Gammarus spp In Different Lights

[KurtM]

I have been fooling around with mini-aquariums again, and for today's amusement tried my hand at imaging a larger critter than I normally tackle: a Gammarus. I'm not up on my amphipod crustaceans, and there are a zillion of these things, so I leave species to the experts. These images are stitches of 6 images each, the source images are single frames, all shot through the 4x objective on the Diaphot TMD. The result are in bright field, DIC (kinda, the 4x doesn't have a matched prism), simple POL, and POL with 1st order red compensator.

The POL images highlight musculature, of course. Overall length from stem to stern is right at 4 mm.

[75RR]

Nice set! Like the mix of illumination techniques.

4x does have a nice depth of field!

The result are in bright field, DIC (kinda, the 4x doesn't have a matched prism) ...

What prism did you substitute for the missing 4x one?

Have you seen Cactusdave's posts on mismatch DIC objectives?

https://www.photomacrography.net/forum/ ... hlight=dic

[rnabholz]

Interesting fellow, don't believe I have ever seen one before.

Nice study in illumination effects too.

[KurtM]

Rod, I'll bet you have seen these guys before, probably took 'em for some sort of insect larvae zipping around. I believe they're fairly ubiquitous in FW pond/river/birdbath samples. Big enough to be easy naked-eye visible, this one is 4 mm long and as I'm sure you know that's 1/8" ... and we old draftsmen typically made the lettering on our drawings 1/8". For whatever reason, lately I've been taking increasing interest in the larger denizens of FW samples, particularly cladocera. This amphipod, plus a few of his buddies, were in a sample I was about to discard.

75, you bet I've seen Cactus Dave's article, and have studied it quite a lot as I'm sure you have too. I also once saw where Charles Krebs mentioned occasionally mismatching prisms on purpose to get improved DIC effect on the camera sensor. So I've learned to experiment, even trying prisms upside-down where possible (Zeiss but not Nikon). In the TMD's case, the prism for the 10x lens works best with the 4x; the others present an increasingly narrow, abrupt extinction band.