Posts Tagged ‘studio photography’

Proof of concept: NiSi NM-200 manual focus rail

January 24, 2023

The following focus stacked composite image was created using a Fujifilm X-T3 mirrorless digital camera and Laowa 25mm Ultra Macro lens mounted on a NiSi NM-200 manual focus rail.

Toy dinosaur at 2.5x magnification.

The Laowa lens was set for 2.5x magnification and an aperture of f/4, the “sweet spot” for that lens.

The subject is a small toy dinosaur, viewed from above the anterior end of the dino. The toy is approximately 3.2 cm long (~32 mm).

The carriage of the focus rail was moved 200 µm (micrometers, also known as microns) per step, equal to 20 increments on the NiSi NM-200. A total of 28 photos were taken. A little back of the envelope math shows the carriage moved a total of 5.6 mm from beginning to end.

200 microns x 28 = 5,600 microns

5,600 microns x 1 mm/1,000 microns = 5.6 mm

The camera was set to record JPG plus RAF files. For simplicity the composite image was focus stacked in Adobe Photoshop using the JPG files straight out of the camera. The final output was slightly cropped and sharpened.

Look closely at the full size version of the composite image. I don’t see any glaring “focus banding” so the 200 micron step size seems to have worked. [See Post Update, at the end of this blog post.] As always, a sample size of one proves nothing. That said, I feel confident the NiSi NM-200 works as expected and will be a useful aid for creating macro focus stacked composite images.

Tech Tips

i used a step size of 200 microns — much larger than the 10 micron precision limit of the NiSi NM-200. My goal was to choose the largest step size that wouldn’t show “focus banding.” I’m not sure what the maximum “safe step size” is, given the settings for my photo gear, but it appears 200 microns doesn’t exceed that value.

Related Resource:Toy dinosaur” includes a photo (shown below) that shows the entire toy. 2.5x magnification is more than it seems!

08 DEC 2020 |  BoG Photo Studio | toy dinosaur

Post Update

In the preceding post I wrote “Look closely at the full size version of the composite image. I don’t see any glaring “focus banding” so the 200 micron step size seems to have worked.”

Well, someone with more experience than me in creating focus stacked composite images actually looked closely at my image, and here’s what he saw.

Annotated image used with permission from Rik Littlefield.

Rik Littlefield, creator of Zerene Stacker, noticed there is in fact a problem with focus banding in my composite image. Rik highlighted the focus bands with a series of black dots.

My decision to use a “safe step size” of 200 microns was based upon the output from a depth of field – step size calculator that I now realize is fatally flawed. Honestly I can’t remember which calculator I used, but I can tell you this — after using Rik Littlefield’s DOF Calculator to determine the safe step size for the same macro rig is 58.038 microns, I knew 200 microns must not have worked as well as I thought. And as you can see in Rik’s annotated image, a step size of 200 microns is too big. Sincere thanks to Rik for his feedback!

Copyright © 2023 Walter Sanford. All rights reserved.

Focus rails: Useful or useless?

January 17, 2023

For the purpose of this blog post, let’s establish there are two types of focus rails: manual; and automatic. This blog post will focus on manual focus rails only.

Manual focus rails are useful for positioning your camera more easily when it’s mounted on a tripod. But most manual focus rails are essentially useless as an aid for creating macro focus stacked composite images. The issue is lack of precision. More about that later in this post. For now, let’s review a brief history of manual focus rails that I own and have tested.


The Neewer Pro 4-Way Macro Focusing Focus Rail is the first focus rail that I bought and is still available for $39.99 from Amazon. Trust me when I tell you this focus rail is anything but “Pro” but the price was right (given what I was willing spend for a focus rail at the time) and turned out to be a relatively inexpensive way to gain experience using a focus rail.

The rulers on each rail are marked in centimeters; the finest increments are in millimeters.

Photo Credit: Amazon.


My next focus rail — the Novoflex Castel-L Focusing Rack — was a significant step up in price. The same model is still available for $279.00 from B&H Photo — overpriced like all products made by Novoflex, in the opinion of this author. This is one of only a few pieces of photography gear that I really regret buying.

Although the focus rail is beautifully engineered and operates smoothly it is no more precise than the much less expensive Neewer focus rail: the ruler on the rail is marked in centimeters; the finest increments are in millimeters.

Photo Credit: B&H Photo.


I recently bought a NiSi Macro Focusing Rail NM-200 for $199.95 from B&H Photo. At that price point, the NiSi focus rail is five times more expensive than the Neewer focus rail, and nearly $80 less than the Novoflex focus rail.

Notice the ruler on the rail is still marked in centimeters and millimeters. So why would I waste more money on another focus rail that is no more precise than the other two? Because it turns out it is more precise than the other two!

Photo Credit: B&H Photo.

Look closely at the larger adjustment knob shown below. One full rotation of the knob moves the carriage one millimeter, or 1,000 micrometers (microns). The knob is marked in 100 increments, so each increment on the knob is 10 microns. Now we’re getting somewhere!

Photo Credit: B&H Photo.

Thanks to Andy Astbury for verifying the math using a digital caliper. (As part of my due diligence, I watched Andy’s video before deciding to buy the NiSi NM-200.)

Screen capture from YouTube video by Andy Astbury.

Do you need a focus rail with 10 micron precision?

In a word, yes!

According to Allan Walls, macro photography guru extraordinaire, the following list shows the “safe step sizes” for different macro lenses. Remember, the goal is to move the camera with 30% overlap between steps.

  • 1x:1 = 0.7 mm (700 micrometers, a.k.a., microns) ← 70 increments on NiSi NM-200
  • 2x:1 = 0.25 mm (250 microns) ← 25 increments on NM-200
  • 4x = 0.1 mm (100 microns) ← 10 increments on NM-200

It’s somewhat unclear whether the preceding step sizes include the recommended 30% overlap. In Macro Talk #18, Allan said a step size of 60-70 microns would be better at 4x magnification (6-7 increments on the NiSi NM-200). Another macro photographer recommends a step size of 50 microns at 4x (5 increments on the NM-200). Regardless of which advice you follow, the NiSi NM-200 is capable of getting the job done.

As you can see, even at 1:1 magnification the recommended step size is less than a millimeter. The same idea expressed another way: It’s impossible to use a focus rail marked in one millimeter increments to do macro focus bracketing with right size step between images consistently. That is, unless you find a manual focus rail like the NiSi NM-200 that enables fine adjustments.

Testing 1, 2, 3 …

I just set up my new NiSi focus rail and need to do some testing. I am encouraged by the results achieved by other photographers using the same rail. Stay tuned for a follow-up blog post in the near future.

Related Resources

Copyright © 2023 Walter Sanford. All rights reserved.

Fossil shark tooth, revisited

June 10, 2022

This blog post features a photo of a fossil shark tooth that I collected from the Lee Creek Phosphate Mine in Aurora, North Carolina. I didn’t record the exact date when I collected this specimen, but it was sometime between 1984 and 1989. The mine is currently open for phosphate mining, but it’s closed to the public for fossil collecting.

At the time I collected the tooth, the species of shark was called Carcharodon megalodon. Subsequently, the scientific name was changed to Carcharocles megalodon.

C. megalodon lived in “shallow” seas approximately 10 million years ago. 10 million years seems like a long time on the human time scale, but isn’t long ago on the Geologic Time Scale.

Size and jaw placement

The following annotated image shows one method for measuring the size of a fossil shark tooth. The “slant height” of the tooth is approximately four and one-quarter inches (~4 1/4″) long, as measured along the straighter edge of the tooth (lower edge, relative to the photo).

According to Gareth Williams, a member of the Megalodon Maniacs Facebook group, the tooth is from the upper jaw (lateral).

Lee Creek Phosphate Mine | C. megalodon (lingual side)

Photoblog post flashback

On 11 May 2020 I published a blog post entitled “Focus bracketing using Fujifilm X-T3” that features the same ruler shown in the preceding photo.

The 7″ plastic ruler is from the Calvert Marine Museum. Do you know why the small ruler is 7″ long rather than the more common 6″ length? Please leave a comment if you know the correct answer. Source Credit: Focus bracketing using Fujifilm X-T3.

The reason the ruler is 7″ inches long is because that’s the length of the largest fossil shark teeth ever collected — the holy grail for fossil hunters!

Tech Tips

The Adobe Photoshop “Ruler Tool” can be used to measure the number of pixels between any two points along the ruler shown in the preceding annotated image.

60s ‘shop: Using the ruler tool to measure distances in Photoshop CC, by Photoshop for the Scientist (1:00) provides a clear and concise explanation of how it’s done.

The resulting value (in pixels) can be used to set a custom scale in Photoshop in order to make other measurements of the tooth virtually.

Related Resources

Copyright © 2022 Walter Sanford. All rights reserved.

Fossil shark tooth

June 3, 2022

Sometimes I start working on a blog post by shooting some quick-and-dirty test shots of the subject, such as the following photos of a fossil shark tooth taken using the “Camera” app on my Apple iPad mini 6. Both photos featured in this post are unedited, that is, they are the original JPGs straight from the “Photos” app on the iPad.

Labial side

The first photo was taken with the built-in camera flash turned on. In my opinion, the light is a little too “harsh.”

The photo shows the side of the tooth that faces outward from the mouth of the shark. Notice the tooth edges are serrated.

There are at least two ways to measure the size of a fossil shark tooth. (More about how to measure shark teeth in a follow-up blog post.) This tooth is approximately four and one-quarter inches (~4 1/4″), as measured along the straighter edge of the tooth (right side, relative to the photo).

Lingual side

The last photo was taken was taken using a small LED light and the flash turned off. The LED lighting is better than the flash light, but the specular reflection located near the upper-middle of the tooth enamel is a little distracting.

The photo shows the side of the tooth that faces inward. Three prominent parts of the tooth are easy to identify in the following photo, including the crown/enamel (top), bourlette (middle), and root (bottom).

In the opinion of the author, the lingual side of a shark tooth is often displayed because it is more visually appealing than the labial side.

What’s next?

I plan to shoot better photos, of course, and annotate some of them in order to make it easier to identify the parts of the tooth.

I will describe when and where I collected the fossil shark tooth, identify the species of shark, and provide an estimate of its approximate age on the Geologic Time Scale.

Finally I will explain how to measure the size of a fossil shark tooth, and how to determine whether the tooth is from the upper- or lower jaw, including its approximate position along the jaw line.

Related Resource: Fossil shark tooth, revisited.

Copyright © 2022 Walter Sanford. All rights reserved.

Best Photos of 2021

December 24, 2021

The following gallery shows my “Best Photos of 2021.” 10 photos are presented in chronological order beginning in January 2021 and ending in December 2021.

01 January 2021

Buzz Lightyear: “To 2021 and beyond!”

Original blog post: To 2021 and beyond!

13 APR 2021 | Prince William County, VA | Selys’s Sundragon (male)

13 APR 2021 | Prince William County, VA

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (female)

05 JUN 2021 | Fairfax County, VA | Unicorn Clubtail (male)

17 JUN 2021 | PNC. Wm. County | Yellow-sided Skimmer (female)

17 JUN 2021 | PNC. Wm. County |  Bar-winged Skimmer (mature male)

09 September 2021

It’s challenging to get all of the parts aligned for an image like this. In this case it’s close but not perfect. It would have been helpful to compose the shot with my camera tethered to a computer that features a larger screen than the one on the back of my camera.

All of that being said, the slight imperfections don’t diminish the visual impact of this image: Comet Darner (Anax longipes) exuviae are much larger than Common Green Darner (Anax junius) exuviae!

Relative size of exuviae from Anax junius versus Anax longipes.

Original blog post: Anax junius versus Anax longipes

04 October 2021

This is the only photo I’ve added to my Odonart© Portfolio recently. I love this beautiful specimen!

Comet Darner (Anax longipes) | exuvia (lateral)

Original blog post: Comet Darner exuvia: photo sketch pad

14 December 2021

Annotating images adds value, and I think it’s an under appreciated art form.

Original blog post: Determining final instar the Cham way

Copyright © 2021 Walter Sanford. All rights reserved.

Test shots

September 17, 2021

I have been working on the prototype for a homemade curved clear plastic tray that is intended for staging subjects against a white background.

My goal for Thursday: Test the prototype stage using a toy mini-lizard as the model for some test shots, and if the proof-of-concept were established, substitute an odonate exuvia for the toy lizard and shoot another set of photos.

16 SEP 2021 | BoG Photo Studio | toy mini-lizard

Well, you know what they say about the best laid plans! First, a line of fairly strong thunderstorms moved through the region where I live so I had to shut down my computer equipment. Second, the Washington Football Team played the New York Giants on Thursday Night Football so I had to watch the game. That’s right, had to watch. Turns out it was time well-spent.

Bottom line: I never finished the test shots of the toy lizard, and of course that means I didn’t shoot any photos of a real scientific specimen.

The curved surface of the clear plastic stage caused reflections from the single external flash that was used to light the subject. I had just figured out a work-around when the thunderstorms rolled in: I took 14 test shots; only the last one (shown above) is usable. I hadn’t intended to create a photo with a pure white background, but it was easy to adjust the image exposure during post-processing.

The Backstory

What’s my motivation? Many macro photographers use insect pins for mounting small subjects like odonate exuviae. I think there’s a big problem with that technique: The position of the pin is permanent. In other words, if the pin is attached to the ventral side of the specimen then it’s challenging at best and impossible at worst to take clean, clear shots of that side of the subject. I don’t want to use insect pins because some of my specimens are one of a kind.

For quite some time, I’ve been experimenting with the use of flat clear plastic stages as a solution for this problem. I think a curved stage might be a breakthrough, but more testing is required to be sure.

For example, notice the color fringing near the tip of the lizard’s tail — I’m not sure what caused that problem in only one part of the photo, therefore I don’t know how to fix it. Yet.

To be continued. Please stay tuned.

Copyright © 2021 Walter Sanford. All rights reserved.

Sumo Citrus still life

March 19, 2021

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.

Tethered shooting using Canon EOS Utility

March 5, 2021

Canon EOS Utility (EOS-U) can be used to tether many models of Canon digital cameras with computers (running either macOS or Windows). For example, my Canon EOS 5D Mark II appears on the list of cameras supported by EOS-U.

Canon EOS-U is like a box of chocolates — you never know what you’re going to get! The way that tethering looks and functions seems to depend upon a combination of your camera model and your computer operating system.

My new 13″ Apple MacBook Air (M1, 2020) features the “Big Sur” macOS. The drop-down menu for “Operating System” (shown below) doesn’t list either “Big Sur” or “Catalina” — the last two versions of macOS. So I selected “macOS Mohave v10.14” …

and downloaded/installed “EOS Utility 2.14.31b for Mac OS X.”

Canon EOS Utility 2

Here’s how to get started. Tether your camera to a computer using an appropriate cable for your camera and computer.

Trouble-shooting tip: Set the camera Drive Mode for “One Shot” before tethering your camera to a computer. EOS Utility 2 doesn’t work when the Drive Mode of my Canon EOS 5D Mark II is set for Timer (either 2 s or 10 s).

Launch Canon EOS Utility 2, or EOS-U 3 if you are using a newer camera than me. The “Main Window” (shown below) should appear on screen. Click on “Camera settings/Remote shooting.”

The “Capture Window” (camera control panel) should appear on screen, as shown below.

Click on the button labeled “Preferences…” that is located in the lower-left corner of the “Capture Window” (camera control panel). The following screenshot shows all of the categories of preferences.

Select Preferences → Basic Settings in order to set the “Main Window” to show on startup. I recommend ticking the checkbox to automatically display the “Quick Preview” window whenever a photo is taken.

Select Preferences → Remote Shooting in order to set where photo files are saved. My camera is set to shoot RAW files only; CR2 files are saved to both my camera and computer, as indicated by the icon in the camera control panel that looks like a computer + camera.

Select Preferences → Destination Folder to specify the location where photo files will be saved on your computer. My preferences are as follows.

Help requested: A little help from my readers, please. What is the purpose of the “Monitor Folder,” shown in the preceding “Preferences” panel? I speculate it might be a folder that is watched by “Digital Photo Professional 4,” free photo editing software available from CanonUSA.

Subfolders within the “Destination Folder” are created automatically as per my preferences.

Select Preferences → Linked Software in order to set an application that will be used to open photo files automatically. In my case, I registered “Preview,” an Apple graphics utility.

When you click on the “Register…” button the first time, what you see varies depending upon whether you are using EOS Utility 2…

or EOS Utility 3. In either case, all of the default options are Canon applications. If you would prefer to link to a non-Canon application, then select “None” and press the “Register…” button again in order to browse the applications available on your computer.

The “Capture Window” (camera control panel, shown below) can be used to change some but not all settings for my Canon EOS 5D Mark II. The initial settings shown by EOS-U should be the same as your camera before it was tethered to your computer.

The grayed-out “M” indicates my camera is set for Manual shooting mode. The shooting mode (M, Av, Tv, P, etc.) cannot be changed in software — you must make that setting by turning the dial on your camera. Also, adjusting the focal length of a zoom lens cannot be done remotely by the software.

The camera settings shown in black can be adjusted remotely. For example, I set the White Balance for “Flash,” as indicated by the lightning flash icon. Press the virtual shutter button when you’re ready to take a photo.

EOS-U 2 seems to have no idea what type of lens is mounted on the camera. In this case, I used my Canon “Nifty 50” lens (EF 50mm f/1.8 II) to take some test shots. The “Quick Preview” panel appears after you take a photo. (The panel is resizable.)

Each photo also opens automatically in “Preview” based upon my settings in Preferences → Linked Software. To some extent, it’s redundant to open photos in both EOS-U “Quick Preview” and Apple “Preview.” My goal is simply to demonstrate for Fujifilm that Canon has shown it is possible to make “Linked Software” work on a computer running the Big Sur macOS.

Click the “Live View shoot…” button, located near the bottom of the “Capture Window” (camera control panel), in order to display the “Remote Live View window” (shown below). There you can set the focus point, and zoom in/out. Other options might be available depending upon your camera model.

Canon EOS Utility 3

Mike Powell, my good friend and photowalking buddy, experimented with his Canon EOS Rebel SL2 tethered to Canon EOS Utility 3. Sincere thanks to Mike for patiently helping me begin to figure out things that are software-dependent and things that are camera-dependent.

Your mileage might vary, but it’s worth noting that the “Capture Window” (camera control panel) for Mike’s Canon EOS Rebel SL2 shows several options that aren’t available for my older Canon EOS 5D Mark II. This is the box of chocolates thing that I mentioned at the beginning of this blog post.

For example, the Drive Mode [Single Shot, Continuous, Timers (2, 10 s)] can be set in EOS-U 3 (on Mike’s camera) but can’t be set in EOS-U 2 (on my camera).

Look closely at the “Capture Window” (camera control panel, shown above). Notice the icon for a movie camera located to the right of the “Live View shoot…” button. That button is supposed to enable remote video shooting; neither Mike nor I have tested the process.

Here’s a screenshot of the “Remote Live View window” on Mike’s computer. Notice the EOS-U 3 window features more buttons than EOS-U 2. Also notice the histogram shown in the lower-right corner, a useful tool that isn’t featured in EOS-U 2 using either Mike’s Canon EOS 50D or my Canon EOS 5D Mark II.

What are the take-aways?

Canon EOS Utility can do so much more than tethered shooting using Adobe Lightroom Classic that EOS-U is the tool of choice for tethered shooting with my Canon camera. I feel like I’ve just scratched the surface of what EOS-U can do, and I’m looking forward to further exploration and experimentation.

Who knows? The joy of tethered shooting with EOS-U — and the frustration of the limitations of the software when used with my older camera — might motivate me to buy a new Canon mirrorless digital camera. That is, assuming Canon introduces a pro-grade camera with an APS-C sensor at a sub-$4K price point. If I’m going to spend $4,000 or more for a camera — the current price range for higher end Canon mirrorless digital cameras — then I think my money would be better spent on one of the Fujifilm GFX medium format digital cameras.

Related Resources



Copyright © 2021 Walter Sanford. All rights reserved.

Tethered shooting using my Canon EOS 5D Mark II

March 2, 2021

Adobe Lightroom Classic can be used to tether many models of Canon and Nikon digital cameras with computers (running either macOS or Windows) that meet the system requirements. For example, my Canon EOS 5D Mark II appears on the list of tethered cameras supported by Lightroom Classic.

The Canon EOS 5D Mark II works as expected when tethered with Lightroom Classic. “Live View”¹ on the computer screen plus the ability to change camera settings and trigger the camera using Lightroom are among many features I like. And it’s FREE. Well, free as long as you have Lightroom Classic and that isn’t free.

Getting started

Here’s how to get started. Tether your camera to a computer using an appropriate cable for your camera and computer. Launch Lightroom. Select File → Tethered Capture → Start Tethered Capture…

The “Tethered Capture Settings” window appears on screen; carefully consider the settings you make (especially the “Destination”) since Lightroom doesn’t like it when you change the location of photo files on your computer!

After your camera is connected to the computer successfully, select File → Show Tethered Capture Window. “Command-T” is the keyboard shortcut to toggle on/off the “Tethered Capture Window,” shown below.

The window indicates the name of the camera connected to your computer and the “Session Name” that you used when you set the “Tethered Capture Settings”; in this case I used the name “Studio Session.”

Click the button labeled ¹”Live” in order to see a “Live View” of your camera. With my camera tethered to an Apple MacBook Air (M1, 2020) — by far the fastest computer I own and one of the faster computers currently on the market — there is so much video lag that I found “Live” to be unusable!

You can adjust a limited number of camera settings, including shutter speed, aperture, ISO, and white balance (shown from left-to-right in the “Tethered Capture Window”).

“Develop Settings” can be applied on-the-fly to photos as you shoot them. I’m not sure how useful this feature is, given the fact that it seems like every photo requires a unique set of adjustments/edits.

Lastly, there is a shutter button that triggers the camera remotely.

To end the session, select File → Tethered Capture → Stop Tethered Capture.

What are the take-aways?

Essentially that’s all you can do using Adobe Lightroom Tethered Capture. As far as I can tell, there’s no way to autofocus the camera lens remotely. (Please correct me if I’m wrong.) That would be a nice feature to add. (Hint-hint, Adobe.)

In contrast, the Canon EOS Utility can do so much more I think it’s the tool of choice for tethered shooting with my Canon camera. Please stay tuned for my next blog post in which I will do a complete review of Canon EOS Utility 2, plus a few comments about Ver. 3.

Related Resource: Tethering just got better in Lightroom Classic CC, by Terry White (20:59). “Adobe Evangelist Terry White shows how to shoot tethered into Lightroom Classic CC with the enhancements released in the February 2019 update.” Source Credit: Show notes. Note: Mr. White refers to the refers to the “Tethered Capture Window” as “Tether/ing Bar.”

Copyright © 2021 Walter Sanford. All rights reserved.

Dromogomphus spinosus exuvia (dorsal view)

February 19, 2021

Gomphidae (Clubtails) is the second largest family of dragonflies, behind Libellulidae (Skimmers). Many types of clubtail larvae (nymphs)/exuviae look similar, adding to the challenge of identifying some specimens to the genus and species level.

This specimen has a flat labium that doesn’t cover the face (not mask-like), indicating it’s either Aeshnidae (Darners) or Gomphidae; the shape of the body suggets Gomphidae. Several more field marks can be used to identify this specimen as a Black-shouldered Spinyleg (Dromogomphus spinosus) exuvia.

16 FEB 2021 | BoG Photo Studio | D. spinosus exuvia (dorsal)

The specimen is approximately 3.3 cm (~1.3 in) long, measured from head to tail. Notice the mid-dorsal hooks/spines located along the abdomen of the body.

At first I thought the exuvia might be a species from the genus Stylurus, based upon the mid-dorsal spine on abdominal segment nine (S9). After careful examination of two excellent photo-illustrated PowerPoint presentations by Kevin Hemeon at NymphFest 2016 (see Related Resources, below), I noticed none of the species in the genus Stylurus have dorsal hooks. That’s when I realized the specimen must be D. spinosus. Eureka! Source Credit: Dromogomphus spinosus exuvia – a blog post published on 28 June 2019 by Walter Sanford.

Related Resources

The following PowerPoint presentations by Kevin Hemeon are available in the “Files” section of the Northeast Odonata Facebook group. Direct links to the documents are provided below.

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

Tech Tips

The photograph featured in this blog post is a “one-off,” that is, a single photo rather than a focus-stacked composite image. The camera lens was set for f/16; the camera body was set for ISO 160 and a shutter speed of 1/250 s.

The photo was taken using a Fujifilm X-T3 digital camera, Fujifilm MCEX-11 extension tube, Fujinon XF80mm macro lens (120mm, 35mm equivalent), and an array of external lights.

Two external flash units were used to create the white background by cross lighting the front of a piece of white plastic; another flash was used to light the subject. A Sunpack LED 160 was used as a focusing aid.

RAW FILE CONVERTER EX 3.0 was used to convert one RAW (RAF) file to a TIFF file. The TIFF file was edited using Apple Aperture and sharpened using Photoshop.

Copyright © 2021 Walter Sanford. All rights reserved.

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