Butterfly galea (tongue)

[Rylee Isitt]

I should note that the shot below is from a purchased prepared slide. There are no details about what species of butterfly this is.

I wanted to finally try out two objective lenses I purchased from a user on this forum: a Nikon M Plan 20x LWD and a Nikon M Plan 40x ELWD.

I mounted them on a cheap no-name microscope body that I mount my camera to directly (to the turret) and use extension tubes or a bellows to control the tube length.

This was taken only as a test shot, but I thought some viewers here might enjoy it. It was taken with continuous transmitted light (an LED lamp built into the scope). This is 28 frames manually advanced with the fine focus knob and stacked using PMAX in Zerene Stacker. The objective I used for this was the Nikon M Plan 40x ELWD. It's designed for a 210mm tube length, but I only used a 36mm extension tube (although the dovetail to EOS adapter combo adds another 20mm (approximately).



There appears to be some false colors, but otherwise I'm very happy with the detail. Not a bad lens at all!

[rjlittlefield]

Interesting in many respects.

I gather that this is a whole tongue, both halves still joined, and apparently it's been partially cleared so that most of the detail we're seeing are reinforcing rings that maintain the tubular cross-section. The two halves would be tightly joined on the inside of the coil with an interlocking mechanism, and sealed on the outside with fine overlapping plates ("galea legulae") as discussed in this thread.

Have you measured the actual magnification of this image? I'm thinking that the setup you're describing has a total extension of something like 40 mm objective-to-dovetail + 20 mm dovetail-to-EOS plus 36 mm extension-tube + 44 mm Canon-EF-flange-distance = 140 mm total extension from objective to sensor. With reasonable assumptions, that would make an overall magnification of something like 40*140/210 = 27X. If that's correct, then we're looking at a pretty small butterfly proboscis -- roughly 1 mm across, more or less, depending on what sensor size you're using.

--Rik

[Rylee Isitt]

Since the combination of tubes I used is fixed (ie not a bellows) I can reconstruct the apparatus exactly and use a micrometer stage to calibrate against. That would be the best way to determine size, I think.

There are signs of plates and zipper like structures in there, if you look closely around the edges. Layers of structure were more obvious when looking at individual slices and changing focus, but some of this detail doesn't seem to be as obvious is the final 2d image. See those projections near the tips? Looks like a "zipper" that has come apart.

The slide was indeed a whole mount, including parts of the head and eyes as well. Since I didn't prep it myself, I don't know the details much beyond that, sadly.

I'm using a 1.6x crop camera.

I will post the micrometer image and a single slice (so that resizing by ZS to align things won't be a factor) tomorrow.

[Cactusdave]

A very interesting view of a favourite subject of mine. It nicely compliments some conventional microscope images using different types of illumination, that I made of the butterfly proboscis a while back. http://www.photomacrography.net/forum/v ... fly+tongue

[Rylee Isitt]

Those are nice shots, Cactusdave! The illumination in particular (I've developed a fondness for darkfield and DIC) is very nice.

The structure is very interesting, and I'd like to get a better shot of this zipper mechanism, but alas my prepared slide doesn't do the job.

I purchased a box of 100 various prepared slides from a Canadian microscope online retailer via eBay (same ones available from AmScope). These are modern slides, so nothing collectible. Mostly common things like plant cross sections, spores, pollen, insect bits, etc. They are usually fairly well prepared (no bubbles or debris) and often nicely stained, but sadly details on the species, stains, etc are completely lacking. But whenever I have an itch to break out the compound microscope but don't have a specimen on hand, they are great fun just to look at. I haven't photographed many of them, but am thinking I could use this collection to hone my skills with the microscope and the various forms of lighting that entails.

[Charles Krebs]

The results look very good.

With all of the Nikon 210mm M Plan Achromats I've used there will be some of the "false color" you refer to. Typically a blue/purple "haze" in certain areas. Actually, unless you have removed some, this look quite good in this regard. I can only see a hint of theses "blues" toward the tip of this subject.

Keep in mind that these objectives were intended to be used with no cover-slips. But the two you mention have NA's of 0.40 and 0.50, so you are still under the NA where the effects start to become increasingly noticeable. Generally we think of an NA of about 0.70 or 0.80 as the point where you really need to pay attention to cover-slip characteristics. But as the graph seen on this page ( http://www.olympusmicro.com/primer/anat ... ction.html ) shows, even at 0.40 there will be some degradation if you consider that the cover slip used on your prepared slide is probably in the range of 0.15-0.19mm. One significant aberration that becomes a problem with such a mismatch is spherical aberration. In the "old days" of adjustable draw-tube microscopes, spherical aberration due to incorrect cover thickness was "corrected" by changing the tube length. The draw-tube was shortened if the cover glass was too thick. (Lengthened if too thin). So when looking at covered prepared slides with the Nikon M Plans it is conceivable that a mechanical tube-length shorter than 200mm (as it seems you have done here) might actually yield a slightly better image. The risk you take with shorted tube lengths is that you reduce the size of the image circle produced, and even on an APS-C sized sensor some objectives may start to lose corner and edge sharpness.

[Rylee Isitt]

Thanks for the comments, Charles!

I do have a draw-tube monocular objective that I purchased on eBay some time ago. The seller called it a "Lomo monocular".

Here's an (apparently) exact copy for sale: http://www.ebay.com/itm/LOMO-PHOTO-Mono ... 5d30e2f37b just to give you an idea of what I'm using.

I wanted an optics-free tube that I could essentially use as a bellows. My trinocular head had mirrors and glass plates in it that were not properly aligned, covered in dust, etc.

The funny part is that I ended up not using the tube itself. Instead I unscrewed the silver ring on the base, which turned out to be a dovetail to M42 adapter. From there I was able to build an M42 coupler so that I could attach pretty much any EOS equipment or the M42 bellows to it.

I have to say, that some of this older equipment works as well as, if not better than our modern stuff. You can't do wrong with a hollow tube, but a trinocular head splits light three ways and presents all sorts of optical surfaces where imperfections can creep in.

[Rylee Isitt]

So, here is a non-stacked image I made this morning to give you a sense of scale. The scale is determined using a stage micrometer.



Also, to make it more clear that my original image is just a small section of a larger structure, here is an overview (not stacked, shot with a Nikon 10/0.25 from Edmund Optics)

[rjlittlefield]

Thanks for the micrometer test. Based on the scale bar and assuming a 22-23 mm sensor width, I get around 28-29X. Pretty close to previous estimate of 27X based on extension lengths.

That 40X objective looks to be holding up well even into the corners.

--Rik

[Rylee Isitt]

Rik,

Yeah, that was a good estimate on your part!

I find that the corner image quality is greatly affected by the distance of the abbe condenser to the slide, while the diaphragm does nothing at all until it's almost completely closed, at which point you end up with lots of vignetting and become quite certain that the abbe condenser is misaligned, because the bright spot is off to one side