Making progress (on a steep learning curve)

OK, let me say right at the outset that using a manual focus rail like my new-ish NiSi NM-200 to create a 328-photo focus stack is insane! So I regrouped, made a new plan, and conducted some tests.

I discovered, albeit too late, that I needed to shoot a lot of  photos for my last focus stack because I chose to use an aperture of f/8 and the “safe step size” for f/8 (at 1x magnification) is 40 µm (micrometers, or microns) — a relatively small step size.

In contrast, at 1x magnification the safe step size for f/11 is 800 µm — during limited testing that seems to be the sweet spot for creating focus stacks that look fairly good using fewer photos.

Canon EOD 5D Mark II DSLR camera plus Canon EF 100mm macro lens (1x, f/11)

The following composite image was created from 20 photos.

The background is the non-reflective side of a piece of black plastic. It’s textured surface appears to be a bad fit for macro photography — notice lots of little white specks on the background. Not good.

f/11 | 1/200 s | ISO 100 | Manual WB (Flash)

But wait, there’s one more thing. Did you notice the copper penny hiding underneath the quarter? Well, it was supposed to be hiding. I borrowed the idea from another photographer whose name I can’t remember. The point is to create some visual relief for the coin in the photo. The plan might have turned out OK if I’d noticed the misalignment of the penny before I did the focus bracketing.

Fujifilm X-T5 mirrorless digital camera plus Fujinon 80mm macro lens (1x, f/11)

The following composite image was created from 26 photos.

For the background, I used the white reference card from a Vello White Balance Card Set (Small). I set the white balance for AUTO WHITE PRIORITY WBW — a new setting (at least new to me) that’s supposed to result in whiter whites.

f/11 | 1/250 s | ISO 125 | WBW

The subject is in focus from back-to-front, and I like the white background. I think this is the best composite image I’ve created so far, but as always, you be the judge.

Fujifilm X-T5 mirrorless digital camera plus Fujinon 80mm macro lens (1x, f/11)

The following composite image was created from 21 photos.

For the background, I used the black reference card from a Vello White Balance Card Set (Small). I think it looks better than the textured black plastic background in the first photo, although I think the white background looks best.

f/11 | 1/250 s | ISO 125 | WBW

Pixel-peepers will notice the far end of the nickel isn’t as sharp as the rest of the coin. That’s because a man-caused disaster forced me to leave out the first two photos in the set. I hope the man responsible for this sloppy work will be held accountable for his actions!

Tech Tips

I think it’s worth noting that all three composite images were created using unedited JPGs straight out of the camera. All of the composite images could have been improved by making a few edits to the RAW files such as adjusting exposure, increasing contrast, and adding a little sharpening, to name a few.

In these test cases, I was looking for focus banding caused by using a step size that’s too big and glitches caused by Helicon Focus, the focus stacking software I used. As far as I can see, no problems.

My NiSi NM-200 is mounted on a Manfrotto 405 3-Way, Geared Pan-and-Tilt Head. The camera line of sight was inclined at a 45° angle relative to the staging surface. That’s less important in this case and more important for an upcoming review of the NiSi NM-200 focus rail.

Both cameras were set for manual exposure. Both lenses were set for manual focus; the combination of manual focus and back-button [auto]focus gives me the best of both worlds.

I use single point focus nearly all the time. I moved the focus point to the farthest point of each subject, then used back-button focus to autofocus on the subject and shoot a photo. Without changing focus from the first photo, I used the focus rail to move across the subject from back-to-front in 800 µm increments (eight numbered increments on the NiSi larger adjustment knob), taking a photo at each step.

More light is required for proper exposure at f/11 than f/8. I used one Sunpak LED-160, one Godox TT685C external flash unit (plus Altura flash modifier), and one Godox MF-12 external flash to light the first subject (Virginia quarter). Two Sunpak-160s and two Godox TT685C external flash units (using Altura and Lastolite flash modifiers) were used to light the last two subjects (quarter and nickel coins).

Related Resources

• Zerene Stacker DOF Calculator
• Fujifilm Colors: Auto White vs Auto Ambience, by pal2tech (12:47)
• Helicon Focus – Quick Start on Mac OS, by HeliconSoft (2:20)

Copyright © 2023 Walter Sanford. All rights reserved.

Theory into practice

What is the “neighborhood play” in baseball?

The “neighborhood play” is a colloquial term used to describe the leeway granted to middle infielders with regards to touching second base while in the process of turning a ground-ball double play. Though it is not explicitly mentioned in the rulebook, middle infielders were long able to record an out on the double-play pivot simply by being in the proximity — or neighborhood — of the second-base bag. Source Credit: Neighborhood Play, MLB Glossary.

And so it is with the 3-D printed plastic “lens” adapter I bought recently for my Fujifilm X Series cameras. The lens adapter, assembled so that it includes all three pieces (photo credit: Nicholas Sherlock Photography), puts a 4x magnification microscope objective in the neighborhood of where it should be for optimal performance.

Naturally I was curious to know exactly where the microscope objective should be mounted  and whether the “lens” actually performs better at that distance.

Theory

I consulted the experts at amateurmicrography.net and asked for guidance specifically for my Fujifilm X-Series mirrorless digital cameras. Thanks to Mr. Rik Littlefield for his quick reply!

First, Rik referred me to an article from the Frequently Asked Questions (FAQ) forum: FAQ: How can I hook a microscope objective to my camera? In this blog post, I will refer to the following annotated image — the first one in the FAQ article.

Photo Credit: Rik Littlefield.

Let me summarize Rik’s detailed answer to my question.

Microscope objectives like the two 4x magnification microscope objectives I own and the 10x objective shown in the preceding annotated image, are designed to work with microscopes featuring a mechanical tube length of 160 mm minus 10 mm for the microscope’s eyepiece. [The microscope objective forms an image at the bottom of the microscope eyepiece, according to Allan Walls in Macro Talk #17 (~8:30).]

The difference of 150 mm (160 mm – 10 mm = 150 mm) is known as the optical tube length, and in photomicrography, is the distance the microscope objective should be mounted from the plane of the camera sensor (as shown above).

Photo Credit: B&H Photo. Fujifilm X-T5 camera (body only).

Fujifilm X Series mirrorless digital cameras have a flange focal distance (FFD) of 17.7 mm, meaning the distance between the plane of the camera sensor and the face of the lens mount on the front of the camera body is 17.7 mm (as shown above). 150 mm – 17.7 mm = 132.3 mm. 132.3 mm is the ideal mounting distance between the “lens” and the outside of the camera body.

The next photograph shows the customized 4x magnification macro rig I was able to cobble together using photography gear I had on-hand already, following Rik’s recommendations. Briefly, several extension tubes were used to mount the “crop” configuration of my 3-D printed plastic lens adapter and 4x magnification microscope objective on a Fujifilm X-T3 digital camera.

My customized 4x magnification macro rig.

Remember, my goal was to move the microscope objective 132.3 mm from the face of the camera body. I combined two 16mm extension tubes and one 10mm extension tube (42 mm total) with the “crop” configuration of the plastic lens adapter (~90 mm from back to front). 42 mm + 90 mm = 132 mm. That’s “good enough for government work” as we say in Washington, D.C.

In contrast, the full size 3-D printed plastic lens adapter moves the microscope objective 142 mm from the face of the camera body — in the neighborhood but a little farther than it should be.

Gear I used

The following equipment list includes all items mounted on the Fujifilm X-T3 camera body shown in the preceding photo.

• Fujifilm MCEX-16 [16mm extension tube]
• Fotasy Extension Tube DG 16mm FX
• Fotasy Extension Tube DG 16mm FX
• 3-D printed plastic lens adapter (“crop” configuration)
• Reakway 4x microscope objective

Finally, a few words about extension tubes designed for Fujifilm X Mount cameras.

Fujifilm makes two extension tubes, as of this writing: the MCEX-11; and MCEX-16. I bought both the 11mm and 16mm extension tubes, although in retrospect, the 11mm is the only one I recommend buying (based upon my usage). It’s good to have found a purpose for the MCEX-16.

When I bought my Fujifilm X-T1 camera more than 10 years ago, Fujifilm didn’t offer extension tubes for sale. “Fotasy” was the first third-party company to sell extension tubes with electronic contacts for Fujifilm X Mount cameras. I bought both sizes that were available (10mm and 16mm) and they worked well, that is until Fujifilm released their proprietary extension tubes — at that point the Fotasy extension tubes were incompatible with newer lenses sold by Fujifilm. Although my older Fotasy extension tubes don’t work with newer Fujifilm lenses, they are perfect in this case because my customized 4x magnification macro rig is all manual all the time.

Gear that could be used (instead of my rig)

What if you don’t have a “junk drawer” of old, unused camera gear like me? Rik Littlefield recommended the following items that could be used for mounting a 4x microscope objective on a Fujifilm X Series camera.

• Get a basic X Mount to M42 adapter like … Fotodiox Lens Mount Adapter Compatible with M42 Screw Mount SLR Lens on Fuji X-Mount Cameras $14.95
• then use M42 tubes to get the required total length, …
• and finally an M42-to-RMS adapter like either … Pixco Lens Adapter Replacement Suit For RMS Royal Microscopy Society Lens to M42 Mount, Caliber:25mm $9.70 [flat] or … RMS Thread for Microscope Objective to M42 x 1 mm Converter Cone Only Adapter $39.99 [cone].

Theory into practice

My customized 4x magnification macro rig was used to photograph a small part of a dime, that is, a 10-cent coin in U.S. currency.

All three photos …

• were shot handheld (not recommended for this camera rig). A single external flash unit was used to light each photo.
• are “one-offs,” meaning they aren’t focus-stacked. At a magnification of 4x the depth of field is extremely shallow. The net result is relatively little of each photo appears to be acceptably in focus.
• are “full frame” (6240 × 4160 pixels), meaning they are uncropped.

For scale, the letters “DIM” are approximately 5 mm wide on the actual coin.

A small part of a dime (10-cent coin in U.S. currency).

A small part of a dime (10-cent coin in U.S. currency).

A small part of a dime (10-cent coin in U.S. currency).

Are these photos better than the test shots I took when I first got the 3-D printed plastic lens adapter? You be the judge, but I think they are qualitatively better.

Related Resources

• FAQ: How can I hook a microscope objective to my camera? Post by rjlittlefield.
• Rube Goldberg 4-5x macro photography rig, a blog post by Walter Sanford.
• 5x magnification, another blog post by Walter Sanford.
• Have you ever wondered…? A blog post by Walter Sanford, related to focal plane mark.

Copyright © 2022 Walter Sanford. All rights reserved.

Rube Goldberg 2.75x macro photography rig

My Rube Goldberg 4-5x macro photography rig can be configured as both a 2.75x and 4-5x magnification macro photography rig. This blog post will focus on the 2.75x configuration.

The first two photos show the 3-D printed plastic lens adapter with the middle segment removed. A Reakway 4-5x microscope objective is screwed into the front of the adapter and the adapter/”lens” combo is mounted on my Fujifilm X-T3 mirrorless camera.

Photo focused on body of Fujifilm X-T3 mirrorless camera.

Photo focused on Reakway 4-5x microscope objective.

A recent blog post featured handheld test shots using the macro rig configured for 4-5x magnification. One of those shots shows the word “Liberty” on a penny, that is, a 1-cent coin in U.S. currency. Remember, the actual size of the word on the coin is approximately 5 mm in length.

A copper penny photographed at 4-5x magnification.

The same penny was photographed at 2.75x using the “crop” configuration of the lens adapter. The camera was handheld, like the 4-5x test shot shown above. Notice how much more of the coin is visible at 2.75x versus 4-5x magnification.

A copper penny photographed at 2.75x magnification.

The last image is a focus-stacked composite of four photos that were shot with the camera mounted on a tripod.

Focus-stacked composite image of four photos at 2.75 magnification.

What are the take-aways?

I own two macro lenses capable of 1-5x magnification: a Canon MP-E 65mm macro lens; and a Laowa 25mm Ultra Macro lens.

The current retail price of the Canon MP-E 65mm macro lens is $1,049.00. It weighs 1.56 pounds (710 g).

The current retail price of the Laowa 25mm Ultra Macro lens is $399.00. The Laowa macro lens is noticeably smaller and lighter than the Canon MP-E 65mm. It weighs 14.11 ounces (400 g).

The 4x microscope objectives from AmScope and Reakway cost ~$25.00 each. (Remember, you need to buy only one objective.) The weight of the “lenses” isn’t listed in their specifications, but they are relatively lightweight. The 3-D printed plastic lens adapter cost $50.00 including $35.00 for the adapter itself and $15.00 handling and shipping from New Zealand. The plastic adapter feels nearly weightless.

For me, the single biggest take-away is for ~$75 I was able to buy an extreme macro photo rig that takes photos that are as good or better quality than comparable macro lenses that cost hundreds of dollars more!

And as a big fan of lightweight camera gear for use in the field, I’m far more likely to carry one of the Rube Goldberg rigs with me than either of its bigger and heavier counterparts.

Related Resources

• Rube Goldberg 4-5x macro photography rig, a blog post by Walter Sanford.
• 5x magnification, another blog post by Walter Sanford.
• Macro Photography with a $20 Microscope Lens, by Micael Widell (9:37). Micael’s video (and related resources in the show notes) piqued my interest in macro photography using microscope objectives.
• Microscope adapter for 4x macro photography with Sony E/FE, Canon EF/EF-S, Nikon F, Nikon Z, Fuji X, M4/3, M42 cameras, by thenickdude.
• Microscope adapter for 4x macro photography, by Sherlock Photography.
• 4X Plan Achromatic Objective Lens with Knurled Ring [AmScope]
• CE, Top quality 4x Plan Microscope achromatic Objective lens, Biological Microscope Lens parts (DIN160/0.1mm) [AliExpress]

Copyright © 2022 Walter Sanford. All rights reserved.

Rube Goldberg 4-5x macro photography rig

By now you might be wondering “What does your Rube Goldberg 4-5x macro photography rig look like?”

The first photo shows an AmScope 4x microscope objective mounted on a plastic lens adapter designed and 3-D printed by Nicholas Sherlock.

AmScope 4x microscope objective mounted on “lens” adapter.

The next photo shows a close-up view of the AmScope 4x microscope objective.

AmScope 4x microscope objective mounted on “lens” adapter.

The next two photos show the plastic lens adapter and microscope objective mounted on my Fujifilm X-T3 mirrorless camera. A Fujifilm 11mm extension tube is mounted between the camera body and lens adapter. More about that in a follow-up blog post.

3-D printed plastic “lens” adapter mounted on Fujifilm X-T3 camera.

A close-up view of the Reakway 4x microscope objective is shown below.

Reakway 4x microscope objective mounted on the “lens” adapter.

Similar microscope objectives

Did you notice two similar microscope objectives are shown in the preceding photos? I decided to buy both of the “lenses” recommended by Nick Sherman — since they are priced so affordably I was curious to see whether one works better than the other. As far as I can tell during limited testing, both microscope objectives perform equally well.

One objective has a smooth barrel …

Photo Credit: AmScope.

The other one has a knurled barrel.

Photo Credit: AliExpress / Reakway.

The lenses are recessed from both ends of the barrel, providing protection against scratching the glass. [Photo Credits: AliExpress / Reakway.]

Both objectives have similar information printed on the barrel.

What does “Plan” mean?

A plan (or planar) objective corrects better for color and spherical aberration than either the semi-plan or the achromatic objective. Plan objectives have a flat field about the center 95% of the image. They also often have larger working distances. Source Credit: What is the difference among achromatic, semi-plan, and plan objectives? Celestron, LLC.

What do the numbers mean?

Microscope objective lenses will often have four numbers engraved on the barrel in a 2×2 array. The upper left number is the magnification factor of the objective. For example, 4x, … The upper right number is the numerical aperture of the objective. For example 0.10, … The lower right number (if given) refers to the thickness of the glass cover slip (in millimeters) assumed by the lens designer for best performance of the objective. Example: 0.17. The lower left number is the tube length in millimeters.

Sometimes objectives have a color ring to aid in identifying the magnification: black (1x), brown (2x), red (4x), …

Source Credit: What do the numbers on the barrel of the microscope objective mean? What about the letters DIN and JIS? Celestron, LLC.

I love the little plastic bottles that are used for storing microscope objectives safely.

Photo Credit: AliExpress / Reakway.

“Crop” configuration

The 3-D printed plastic lens adapter that I bought for my Fujifilm X-Series cameras is comprised of three parts that screw together. Nick Sherlock calls this version the “crop design.”

Photo credit: Nicholas Sherlock Photography.

The crop design is for Sony E, Canon EF-S, Micro Four Thirds, Fujifilm X, or Nikon F crop cameras (or full-frame cameras which have been switched to crop mode) which has a segment of tube you can remove to shorten the tube.

For objectives which cast a big enough image circle, removing this middle tube allows you to reduce the magnification and focus at a greater distance (for the 4x objective I tested this reduced magnification from 4x to 2.75x, and increased working distance from about 28 to 31mm).

Source Credit: Microscope adapter for 4x macro photography with Sony E/FE, Canon EF/EF-S, Nikon F, Nikon Z, Fuji X, M4/3, M42 cameras, by thenickdude.

My Rube Goldberg 4-5x macro photography rig is even more Rube Goldergier than I realized when I bought it. As it turns out, the rig can be configured as both a 2.75x and 4-5x magnification macro photography rig. Very clever design, Nick Sherlock!

I tested the “crop” configuration and am pleased to report it works as advertised. My first impression is 2.75x magnification should prove to be more practical for use in the field than 4-5x. More later in a follow-up blog post.

Related Resources

• Macro Photography with a $20 Microscope Lens, by Micael Widell (9:37). Micael’s video (and related resources in the show notes) piqued my interest in macro photography using microscope objectives.
• Microscope adapter for 4x macro photography with Sony E/FE, Canon EF/EF-S, Nikon F, Nikon Z, Fuji X, M4/3, M42 cameras, by thenickdude.
• Microscope adapter for 4x macro photography, by Sherlock Photography.
• 4X Plan Achromatic Objective Lens with Knurled Ring [AmScope]
• CE, Top quality 4x Plan Microscope achromatic Objective lens, Biological Microscope Lens parts (DIN160/0.1mm) [AliExpress]
• What is the difference among achromatic, semi-plan, and plan objectives? Celestron, LLC.
• What do the numbers on the barrel of the microscope objective mean? What about the letters DIN and JIS? Celestron, LLC.

Copyright © 2022 Walter Sanford. All rights reserved.

Sumo Citrus still life

Have you seen/eaten Sumo Citrus? They’re easy to peel, seedless, and billed as “the sweetest orange.” Delicious, I say!

How I got the shots

I set up a tripod at a good distance from the subject for a 50mm lens. Then I switched cameras without moving the tripod. Each camera/lens combo was set for an aperture of f/8; other camera and flash settings varied as necessary. (See EXIF info for details regarding camera settings for each photo.)

Canon 5D Mark II

Canon EF 50mm f/1.8 II lens (“Nifty 50”), Godox X2TC, Godox TT685C plus Lastolite flash modifier.

18 March 2021 | BoG Photo Studio | Sumo Citrus

Fujifilm X-T1

Fujinon 18-55mm zoom kit lens set for 34mm (51mm, 35mm equivalent), Godox XProF, Godox TT685C plus Lastolite flash modifier.

18 March 2021 | BoG Photo Studio | Sumo Citrus

Fujifilm X-T3

Fujifilm 11mm extension tube, Fujinon XF80mm macro lens, Vello Off-Camera TTL Flash Cord, Godox X2TF, Godox TT685C plus Lastolite flash modifier.

18 March 2021 | BoG Photo Studio | Sumo Citrus

Sumo Citrus from Giant Food

Bernard Nimmons is the produce manager at the Giant Food located in Beacon Center. I sent a Facebook Messenger message to Bernard recently…

I need Sumo Oranges STAT! Are they back in stock?

The following selfie photo is Bernard’s reply to my message. Now you can see why I always say “Bernard puts the ‘Pro’ in Produce.”

Selfie photo used with permission from Bernard Nimmons.

Copyright © 2021 Walter Sanford. All rights reserved.

Swift River Cruiser exuvia (face-head)

The following image is a focus-stacked composite of three photos, focused on the left eye, right eye, and both eyes respectively.

27 May 2017 | Riverbend Park | Swift River Cruiser (exuvia, face-head)

Tech Tips

The dragonfly exuvia was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique.

Several photos were taken using my Canon EOS 5D Mark II digital camera, a Kenko 12mm extension tube, and Laowa 25mm Ultra Macro Lens, set for f/4.0 (the sweet spot for this lens) at ~3.0x magnification.

A Godox TT685C external flash was used to backlight the background (a piece of translucent white plastic) and a Godox TT685F external flash was used as a key light on the right side of the subject. The flash was triggered wirelessly by a Godox X2TC.

Check the EXIF/IPTC info for the photograph for complete details regarding photo gear and camera settings.

Adobe Photoshop CC 2017 was used to create a focus-stacked composite image that was edited using Apple Aperture.

The Backstory

A Swift River Cruiser dragonfly (Macromia illinoiensis) exuvia was collected on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA. This individual is a female.

Copyright © 2020 Walter Sanford. All rights reserved.

When is close too close?

A Swift River Cruiser dragonfly (Macromia illinoiensis) exuvia was collected on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA. This individual is a female. The prominent horn on the head — a key field mark for exuviae from Family Macromiidae (Cruisers) — is noticeable in the following photo, although maybe not recognizable.

27 May 2017 | Riverbend Park | Swift River Cruiser (exuvia)

This photo is one of several test shots using “The Macroscope,” my nickname for the Laowa 25mm Ultra Macro Lens. The Laowa lens was mounted on my Canon 5D Mark II digital camera with a 12mm Kenko extension tube between the lens and camera body.

My new Laowa LED Ring Light was mounted on the front of the lens, powered by an Anker PowerCore+ 26800 PD 45W battery. The Laowa LED Ring Light was used to light the subject. A Sunpak LED-160 Video Light was used as a focusing aid. A Godox TT685C external flash was used to backlight a translucent white plastic background, using the “Meet Your Neighbours” technique. The flash was triggered wirelessly by a Godox X2TC.

The image is full-frame (5616 by 3744 pixels), that is, uncropped. The lens was set for f/4 (the “sweet spot” for the lens) at 4x magification. The camera was set for single point focus and spot metering, centered on the right eye of the exuvia.

Look closely at a full-size version of the image. At this magnification, the depth of field is very shallow: remnant ommatidia are clearly in focus; most of the image is out of focus.

In order to provide some context for what is shown in the first photo, the last photo shows the entire specimen. The photo gear used to take the shot is specified in a previous blog post.

27 May 2017 | Riverbend Park | Swift River Cruiser (exuvia)

When is close too close?

Close is too close when most of the subject is unrecognizable. At 4x magnification, it’s essential to use focus stacking to create a composite image.

The bigger take-away from this test shot is the Laowa LED Ring Light seems to work fairly well, albeit a sample size of one.

Related Resources

• Laowa LED Ring Light for 25mm Ultra Macro Lens
• Anker PowerCore+ 26800 PD 45W
• As promised…

Copyright © 2020 Walter Sanford. All rights reserved.

Neurocordulia yamaskanensis exuvia

A Stygian Shadowdragon dragonfly (Neurocordulia yamaskanensis) exuvia was collected by Freda van den Broek on 10 June 2019 along the St. Croix River in Interstate Park, Polk County, Wisconsin USA.

A two-step process was used to verify the genus and species of the exuvia.

1. Determine the family.
2. Determine the genus and species.

Step 1. Family

First, determine the family of the specimen. For reference, watch the excellent Vimeo video, Identifying dragonfly larva to family (8:06). Here’s the decision tree used to identify the exuvia as a member of the Family Corduliidae (Emeralds).

• The specimen has a mask-like labium (prementum) that covers the face, as shown in Image No. 1, characteristic of four families of odonates: Cordulegastridae (Spiketails); Corduliidae (Emeralds); Libellulidae (Skimmers); and Macromiidae (Cruisers).
• There is no horn on the face-head, characteristic of Macromiidae, so it’s not a cruiser.
• Cordulegastridae has angular, jagged crenulations on its labium, so it’s not a spiketail. The crenulations for Corduliidae and Libellulidae can look similar.
• Look at the anal pyramid to differentiate Corduliidae and Libellulidae: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts. [Editor’s Note: It’s probably Libellulidae if the cerci are less than half the length of the paraprocts.]

In summary, the exuvia has a mask-like labium, and no horn on its face-head. The deeply-scalloped crenulations along the margins of the palpal lobes are a characteristic field mark for Genus Neurocordulia (Shadowdragons) in the Family Corduliidae (Emeralds), according to Kevin Hemeon, member of the “Odonate Larvae and Exuviae” Facebook group.

Although the anal pyramid isn’t shown clearly in any of the photos in this field guide, careful examination of photos of the teneral adult that emerged from the exuvia (see The Backstory, below) confirmed the dragonfly is a Stygian Shadowdragon. Stygian is the only species of Neurocordulia (Shadowdragons) within range of Wisconsin.

A face-head view of the exuvia is shown in Image No. 1, magnified approximately two and one-half times life size (~2.5x). Notice the mask-like labium that covers the face of the exuvia, including deeply-scalloped crenulations with bundles of bristles (setae) located along the margins of the palpal lobes.

No. 1 | Neurocordulia yamaskanensis | exuvia (face-head)

Step 2. Genus and species

Dichotomous keys from Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz, were used to verify the genus and species of the exuvia. Field marks that match this specimen are highlighted in boldface green text.

Key to the Genera of the Family Corduliidae, p. 28.

1a. Pair of small tubercles on top of head; Lateral lobe of labium with 4 or 5 setae (except sometimes 6 or 7 in Neurocordulia). (2)

2a. Strong lateral spines of abdominal segment 8 very divergent and as strong as parallel spines of [S]9. (Neurocordulia)

Alternate Key to the Genera of the Family Corduliidae, p. 29.

1a. Dorsal hooks present and well developed on some of the abdominal segments. (2)

2a. Lateral spines present on segment 8. (3)

3a. Crenulations on distal margin of labial palpi nearly semicircular or even more deeply cut; Lateral spines on segment 8 divergent. (Neurocordulia)

Key to the Species of the Genus Neurocordulia, p. 31.

1b. Lateral spines of 9 about 30 to 50 percent of the length of segment 9, not extending beyond the tips of the caudal appendages; Dorsal hooks of segments 7 to 9 reduced to scarcely more than a short ridge; Length 22 – 24.5 mm. (yamaskanensis)

The following annotated focus-stacked composite images illustrate key field marks described in Soltesz’s dichotomous keys.

Notice the specimen has stubby mid-dorsal hooks along the length of its abdomen, as shown in Image No. 2.

No. 2 | Neurocordulia yamaskanensis | exuvia (dorsal–lateral)

Lateral spines are present on abdominal segments eight and nine (S8-S9): the lateral spines on S8 are divergent; the ones on S9 are parallel.

No. 3 | Neurocordulia yamaskanensis | exuvia (dorsal)

The exuvia is ~2.4 cm (~0.95 in) in length — the longest shadowdragon larva/exuvia in the genus Neurocordulia. Notice the lateral spines on abdominal segment nine (S9) don’t extend beyond the tips of the caudal appendages (terminal appendages), as shown below.

No. 4 | Neurocordulia yamaskanensis | exuvia (ventral)

The Backstory

The following narrative was provided by Freda van den Broeck.

On the last morning of the Wisconsin Dragonfly Society Annual Meeting weekend — Sunday, June 10th 2019 — I made my way to the boat landing in Interstate Park, St. Croix Falls, Wisconsin USA.

The previous morning I’d photographed Mustached Clubtail emerging there (with Alon Coppens). We also saw several teneral Rapids Clubtails. One didn’t have to look hard to find exuviae — they were most easily seen on the rocks, just a couple of feet above the water line. I was really hoping to find a Snaketail emerging, but had no such luck.

Photo of St. Croix river used with permission from Freda van den Broek.

Just as I was about to head back to the car, I spotted a teneral, that had crawled up the rock face higher than I would have expected. At that point, I thought it was “just another baskettail” — we’d seen many of them on Friday afternoon and Saturday. But it was pretty and shiny, so I had to take a few pictures, even though I was late for breakfast. (It was around 8:20 am.)

It was several days later before I realized that it wasn’t a baskettail, but a Shadowdragon, and that a few of the exuviae I’d collected there were Stygian Shadowdragons. Source Credit: Freda van den Broek.

Photo used with permission from Freda van den Broek.

Tenerals are usually tough to identify, but you’ll notice in both photos that the [small yellow] spot on [side of] the thorax is clearly visible. Source Credit: Freda van den Broek.

Photo used with permission from Freda van den Broek.

Related Resources

Odonate Exuviae – a hyperlinked list of identification guides to many species of odonate exuviae from seven families of dragonflies and three families of damselflies.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – N. yamaskanensis exuvia (face-head)

The following annotated focus-stacked composite image shows a Stygian Shadowdragon dragonfly (Neurocordulia yamaskanensis) exuvia collected by Freda van den Broek on 10 June 2019 along the St. Croix River in Interstate Park, Polk County, Wisconsin USA.

10 JUN 2019 | Polk County, WI | Stygian Shadowdragon (exuvia)

Notice the unusual shape of the crenulations between the palpal lobes of its mask-like labium. Is this field mark unique to N. yamaskanensis or common to all species of the genus Neurocordulia (Shadowdragons)? Enquiring minds want to know!

Tech Tips

A Laowa 25mm Ultra Macro lens, set for 2.5x magnification, and Canon EOS 5D Mark II DSPLR was used to photograph the subject against a pure white background (255, 255, 255) following the “Meet Your Neighbours” (MYN) technique.

24 photos were used to create the composite image, including 23 photos taken using an aperture of f/5.6 and one photo taken at f/16.

If you look closely at the full-size version of the image, then you will notice some areas that indicate the final image is a few layers short of a perfect focus stack. But hey, not bad for a new lens and a manual focus rail that I used for the first time!

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Focus-stacked composite image

The following focus-stacked composite image shows a Stygian Shadowdragon dragonfly (Neurocordulia yamaskanensis) exuvia collected by Freda van den Broek on 10 June 2019 along the St. Croix River in Interstate Park, Polk County, Wisconsin USA.

10 JUN 2019 | Polk County, WI | Stygian Shadowdragon (exuvia)

Related Resources

• MYN – Stygian Shadowdragon exuvia
• MYN – Focus Stacking using Adobe Photoshop

Tech Tips

This subject was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique.

24 photos were used to create the composite image, including 23 photos taken using an aperture of f/5.6 and one photo taken at f/16.

If you look closely at the full-size version of the image, then you will notice some areas that indicate the final image is a few layers short of a perfect focus stack. But hey, not bad for a new lens and a manual focus rail that I used for the first time!

Copyright © 2020 Walter Sanford. All rights reserved.