Eye of fly, scale of what?

[rjlittlefield]

I was trying out a new stacking rig tonight and ended up with some images that I thought you might be interested in.

First, the edge of a fly's eye. Notice the little scale stuck on it, near the top of the picture.



Here is an actual-pixels crop of that little scale.



For size comparison, here is a typical moth wing (and some dust) at the same magnification.



That is one small scale stuck on the fly's eye! I have no idea what kind of critter it's from. That fly has just been sitting around dead on my counter for several days. No telling what it was into before I got it, or what's fallen on it since.

Just some test images, but I thought they were interesting.

Canon 300D camera, Olympus CH microscope base, Nikon CF M-Plan 20X NA 0.40 ELWD objective at 18.6X, pingpong ball diffuser with single flash & aluminum foil reflector. 79- and 70-frame stacks at 2.5 micron focus step, Zerene Stacker PMax.

--Rik

[Franz Neidl]

Hallo Rik,

first of all congratulations for your beautul and clear stack pictures.
I think the scale on the right corner is a seta (plural setae). If you look in Google pictures under "compound eye" you will find similar photographs. One example: http://www.micronaut.ch/images/compound-eye-drosophila-58777sig2.jpg
I see also you use a Nikon microscope objective on a Olympus microscope. It is possible without deterioration of the optical quality of the objective? With other words: Can I use Olympus objectives on a Nikon microscope?

Franz

[Eric F]

Superb detail Rik! I'm interested in learning more about your new stacking rig.

Eric

[rjlittlefield]

Franz, thank you for the kind words.

The small scale may be a seta, but if it is I think it is not from this fly. The eyes of this fly are naked (smooth shiny ommatidia but no setae). I just now checked the rest of the eye with direct viewing, using my eyes and no camera. I cannot find any other scales like the one shown.

It is amusing that I had to do that check in a compound scope, using a 10X NA 0.30 objective (100X overall). When I tried using my Bausch & Lomb StereoZoom scope at 45X, NA unknown but small, I could barely see the one scale that I know is there! These high magnification stacked photos are really quite amazing.

About the brand names, if you tried mixing a Nikon objective with Olympus eyepiece, I think you would see some deterioration of the image. In this case I am not really mixing Olympus and Nikon optics. The Nikon objective is the only lens in the system. It is projecting an image directly onto the camera sensor, just as if I were using the objective on bellows. The Olympus base is there only to provide the focusing mechanics. It could be any brand at all.

Eric, this rig is embarrassingly simple: Olympus CH base, Nikon CF objective mounted in the turret, camera with bellows looking down where the scope's head would normally mount. For this quick test, I just set the camera with bellows on top of the base and let its own weight hold it in place. Now that I'm encouraged by the results, I'll figure out some more secure mount.

--Rik

[Eric F]

Wonderful Rik -- it's working great already!. My high-resolution Melles-Griot micrometer, which is on the Z axis of a Newport 460 linear stage, only gets me to a 5 micron focus step. I could try a 'regular' micrometer head and attempt to use the vernier scale to go further -- theoretically to 1 micron (good luck!) -- but that is very difficult for my old eyes, etc. The 462 stages are the way to go (extremely precise & with large diameter micrometers available) but they cost a fortune! I should have stuck with experimenting with microscope focus blocks (problem was I tried various old Leitz scopes, rather than Olympus -- which may be better suited to our goals).

How fine a focus step can you reasonably achieve with your Oly CH? I know we have extensive info on this general topic (Sticky: "Nikon , Olympus, Meiji, Swift Focus Blocks; & Setups") but I can't seem to find an answer to this particular question.

Thanks, Eric

[rjlittlefield]

My unit is 2.5 microns per tick mark. It's trivial to move by half ticks, quarter ticks are not difficult.

Some other Olympus bases are 2 microns per tick, but as far as I can tell that's just a difference in how the knobs are marked. Every picture I've seen shows 200 microns per full turn.

--Rik

[Eric F]

Thanks Rik -- perfect info. My high-resolution Melles-Griot micrometer has 250 microns per full turn (but the knob diameter is only about 1.2 cm!).

[lauriek]

[NikonUser]

I have an Olympus BH2 series brochure:
".......and the minimum increment on the fine adjustment knob represents a stage movement of just 2 microns."
_________________
NU.
neophyte microscopist

[lauriek]

Thanks NU that seems to tie up. There are 200 divisions marked on my fine focus scale, or rather the scale goes from 0-200 with ticks every 2 and numbers labelled every 20. So those numbers are actual microns, I'd hoped as much but it's good to know...

I think I can manage 1/2 ticks okay for 1 micron but I'm not sure about 1/4 ticks, I just tried that and I don't think I can reliably do that for long, maybe 1/3 ticks!
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http://www.laurieknight.net/