Archive for the ‘education’ Category

Recognition in 2018

December 31, 2018

Editor’s Note: Items are presented in reverse-chronological order, based upon the date of the event.

Argia article

Michael Boatwright and I coauthored an article that appeared in the December 2018 issue of Argia, the journal of the Dragonfly Society of the Americas.

Argia 30(4), 2018 (page one of three).

Related Resource: PDF version of the entire article, pp. 14-16.


Signage

Several of my dragonfly photographs are featured on new signage at Melvin L. Newman Wetlands Center, Clayton County, Georgia. The info-graphic, entitled “Mosquito Hawks,” was created by Danielle Bunch, Senior Conservationist for Clayton County Water Authority.

Image used with permission from Danielle Bunch.

Full-size versions of my photographs (featured on the signage) appear in several previous posts on my photoblog.


Next post: Top 10 Photos of 2018.

Copyright © 2018 Walter Sanford. All rights reserved.

Advertisements

Test shots: Stylogomphus albistylus exuvia

December 19, 2018

Bob Perkins collected and reared an Eastern Least Clubtail dragonfly (Stylogomphus albistylus) nymph. This blog post features two focus-stacked composite images of the exuvia from the odonate nymph.

Nine photos were used to create the first focus stack. This small specimen features several easy-to-recognize field marks including large, dish-shaped antennae, distinctive color bands on the legs, lateral spines on abdominal segments eight and nine (S8-9), and terminal appendages tipped with a lighter color.

12 photos were used to create the last focus stack. This individual might be a male, as indicated by what appear to be vestigial hamules on the ventral side of the specimen.

Tech Tips

The following equipment was used to shoot all of the photographs for the two focus-stacked composite images, shown above: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to create the focus-stacked composite images, as well as spot-heal and sharpen the final output.

Copyright © 2018 Walter Sanford. All rights reserved.

Pot o’ Emeralds

December 17, 2018

The following photo shows a plastic container of 20 Downy Emerald dragonfly (Cordulia aenea) exuviae, collected by a good friend during April 2018 in Vienna, Austria. Not a pot o’ gold at the end of a rainbow, but valuable treasure nonetheless!

Thanks to field marks shared by Benoit Guillon, I was able to quickly determine that all of the exuviae are the same species as the specimen featured in a recent blog post.

Benoit’s excellent Web pages are written in French. I used the Google Chrome Web browser to translate French to English.

The exuvia of the Tanned Cordulia is easy to recognize, provided you have good eyes or … a magnifying glass. It is indeed only to present a line, or double black line, on the thorax, clearly visible on the enlargement of the photo on the top left [see Benoit’s Web page]. She also has very large legs and we easily notice the teeth of the palps of her [face] mask in the photo above [see Benoit’s Web page]. As for his eyes, even if they are spectacular [sic?], some other odonate varieties are also strange. Source Credit: Benoit Guillon.

The key field marks — shown in the following focus-stacked composite image — include one- or two dark lines along the thorax, and a dark line between its small, pointy eyes.

Related Resource: Cordulia aenea: exuviae (1/2), by Benoit Guillon.

Tech Tips

I used my Panasonic Lumix DMC-FZ150 superzoom camera and a handheld Canon 580EX Speedlite fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier to shoot the first photo featured in this blog post.

The following equipment was used to shoot all of the photographs for the focus-stacked composite image, shown above: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier. Adobe Photoshop CC 2017 was used to create the focus-stacked composite image, as well as spot-heal and sharpen the final output.

Copyright © 2018 Walter Sanford. All rights reserved.

Test shots: Brachytron pratense exuvia (female)

December 10, 2018

As if it weren’t challenging enough to identify odonate exuviae from species native to the United States of America (where I live), I just started working with some specimens collected by a good friend during April 2018 in Vienna, Austria.

I decided to start with a specimen that I recognized immediately as a member of the Family Aeshnidae (Darners). Here’s the decision tree used to identify the family.

  • The specimen has a flat labium that doesn’t cover the face (not mask-like).
  • Antennae are thin and thread-like (not club-like, as in Gomphidae larvae/euviae).
  • Eyes are large relative to the size of the head.

One-off

The first photo is a “one-off,” that is, not a composite image. The focus point is on the face mask/head; the rest of the subject is in soft focus. I think this is a good way to draw the viewer’s eyes to a specific part of a photo, while adding a sense of depth.

Hairy Dragonfly (Brachytron pratense) | exuvia (face/head-dorsal)

Composite images

The next “photo” is a three-layer focus-stacked composite image: The focus point is on the face mask/head in the first photo; the thorax in the second photo; and the terminal appendages in the third photo. The entire body of the exuvia is acceptably in focus, including the legs.

Notice the unusual shape of the head. Head shape can be used to identify some species in Family Aeshnidae. Source Credit: Sue Gregoire, personal communication. Kestrel Haven Migration Observatory.

In fact, several members of the “Dragonflies and Damselflies – Worldwide Odonata” Facebook group were able to identify this specimen based upon the shape of its head and eyes. Sincere thanks to Tim Termaat, Hartwig Stobbe, and Rob Strik for kindly identifying this specimen as an exuvia from a Hairy Dragonfly (Brachytron pratense), also known as a Hairy Hawker.

Hairy Dragonfly (Brachytron pratense) | exuvia (dorsal-lateral)

The last “photo” is a four-layer focus-stacked composite image: The focus point is on the head in the first and second photos; the thorax in the third photo; and the terminal appendages in the fourth photo. The entire body of the exuvia is acceptably in focus, including the legs.

This individual is a female, as indicated by the rudimentary ovipositor that can be seen clearly on the ventral side of abdominal segment nine (S9).

Hairy Dragonfly (Brachytron pratense) | exuvia (ventral)

Related Resources

Tech Tips

The following equipment was used to shoot all of the preceding photographs: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to create the two focus-stacked composite images, as well as spot-heal and sharpen the final output.

Copyright © 2018 Walter Sanford. All rights reserved.

Test shots: Libellula luctuosa exuvia

December 5, 2018

Bob Perkins collected and reared a Widow Skimmer dragonfly (Libellula luctuosa) nymph. This blog post features test shots of the exuvia from the odonate nymph.

Several field marks worth noting include the “tiger stripes” on top of its head, wing pads that are perpendicular to the body, dorsal hooks (exact number unknown without closer examination), and lateral spines on abdominal segments eight and nine (S8-9).

The exuvia has small pointy eyes, a mask-like labium (prementum) that covers the face, and thin threadlike antennae.

Background color

In this case, “Test shots” also refers to experimentation with the background color. At the suggestion of Larry de March, Western Odonata Facebook group, I shot the test photos on a Vello 18% gray card.

For a background, I prefer something less bright than pure white to simplify exposure and stay within the dynamic range of the camera. Source Credit: Larry de March.

I edited Photo No. 1 and No. 2 a little differently in an attempt to arrive at a pleasing shade of neutral gray. Notice that No. 1 appears bluer in color than No. 2, which seems to be slighty yellowish.

Although a sample size of one doesn’t necessarily prove anything, my initial opinion is I prefer either an off-white or pure white background. Which color do you prefer?

Related Resource: Three-layer focus stack.

Tech Tips

The following equipment was used to shoot both of the preceding photographs: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen both images.

Copyright © 2018 Walter Sanford. All rights reserved.

Test shots: Aeshna umbrosa exuvia

December 3, 2018

Bob Perkins collected and reared an unknown species of odonate nymph from a tiny stream in Carroll County, Virginia USA. The larva emerged from one of Bob’s holding tanks overnight on 23-24 November 2018 and metamorphosed into an adult male Shadow Darner dragonfly (Aeshna umbrosa). Shadow Darner is a member of the Family Aeshnidae (Darners). The following test shots show the exuvia from the odonate nymph.

Test shots of this beautiful specimen were taken using a relatively small aperture of f/16 for greater depth of field. Each photo is a “one-off,” that is, not a composite image. Focus stacks will be created sometime in the near future, after the exuvia is rehydrated and its legs are repositioned  for easier posing.

Lateral-ventral view

The focus point of the first photo is on the right eye. Given the orientation of the specimen, most of the exuvia is acceptably in focus at f/16. For what it’s worth, I really like the composition of this photo!

Notice the specimen has a flat labium (prementum) that doesn’t cover the face (not mask-like). That is a characteristic field mark of two families of dragonflies: Family Aeshnidae (Darners); and Family Gomphidae (Clubtails).

Shadow Darner (Aeshna umbrosa) | exuvia (lateral-ventral)

This individual is a male, as indicated by vestigial hamules that are visible on the ventral side of the specimen.

Dorsal view

The focus point of the next photo is on the head: the head is tack-sharp; the terminal appendages are in soft-focus. Sometimes it’s necessary to create focus-stacked composite images in order to render the subject in focus from head-to-tail and edge-to-edge.

Lateral spines on abdominal segments six to nine (S6-9) indicate this specimen is A. umbrosa.

The focus point of the next photo is on the abdomen, just below the wing pads. Relative to the preceding photo, notice the head is slightly softer in focus while the terminal appendages are slightly sharper in focus.

Tech Tips

The following equipment was used to shoot all of the preceding photographs: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen all three images.

Copyright © 2018 Walter Sanford. All rights reserved.

Field marks for identification of S. rogersi

October 22, 2018

The following annotated images illustrate field marks that can be used for identification of Sable Clubtail dragonfly (Stenogomphurus rogersi). Although there is some redundancy among the images, repetition is a good strategy for learning.

Male

Male Sable Clubtails have eyes that are green to turquoise in color, with a black occiput located between the eyes. They have a thin, black abdomen that flares to a small club featuring thin yellow flanges on abdominal segments seven through nine (S7-9).

The abdomen is marked with small pale dorsal triangles (S3-7) and tiny pale lateral spots. The number of dorsal triangles can vary individually and/or geographically, ranging from S3-5 to S3-7.

08 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

Dennis Paulson, originator of the classification system for thoracic stripes in the Family Gomphidae (Clubtails), describes T1-4 as follows.

T1–2 broad and complete, touching at ends and often with stripe between them restricted and topped with spot; T3–4 fine, T3 incomplete. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 6089-6093). Princeton University Press. Kindle Edition.

Note: T1-4 refers to the dark areas located on the sides of the thorax, not the lighter colored lines and spots. Due to space limitations, thoracic stripes are labeled using a numeral only (e.g., “1”) rather than a letter and numeral (e.g., “T1”).

08 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

Their face is pale, marked with variable black crosslines (as shown in the inset photo, below).

08 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

Male Sable Clubtails, like all male dragonflies, have three terminal appendages, collectively called “claspers.” All male clubtail dragonflies have indented hind wings.

Female

Female Sable Clubtails have a noticeably thicker abdomen than males. The occiput is a pale color, rather than black. Dorsal triangles, located on abdominal segments three through seven (S3-7), are much larger than those found on males. The lateral spots are somewhat larger as well.

05 JUL 2018 | Fairfax County, VA | Sable Clubtail (female)

Female Sable Clubtails, like all female dragonflies, have a pair of cerci (superior appendages) that have little or no function. All female clubtail dragonflies have rounded hind wings.

Related Resource: Stenogomphurus rogersi exuvia.

Copyright © 2018 Walter Sanford. All rights reserved.

Macromia alleghaniensis exuvia

October 6, 2018

Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, collected an odonate exuvia on 07 June 2018 along either Little Otter Creek or Otter Creek near the place where both creeks are distributaries of Otter Lake in Amherst County, Virginia USA.

A two-step process was used to identify 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 Macromiidae (Cruisers).

  • The specimen has a mask-like labium (prementum) that covers the face, as shown in Photo No. 1, characteristic of four families of odonates: Cordulegastridae (Spiketails); Corduliidae (Emeralds); Libellulidae (Skimmers); and Macromiidae (Cruisers).
  • The teeth on the margins of the labium have a regular pattern. (The pattern reminds me of a “spork.”)
  • Its eyes are small, wide set, and stick up.
  • Image No. 2 shows there is a horn on the face-head, characteristic of Macromiidae.

Photo No. 1 shows a face-head view of the exuvia, magnified approximately three times life size (~3x).

No. 1 | Macromia alleghaniensis | exuvia (face-head)

Image No. 2 shows the top of the head of the exuvia, magnified approximately three times life size (~3x). Notice the prominent horn on the face.

No. 2 | Macromia alleghaniensis | exuvia (head-horn)

Step 2. Genus and species

Two dichotomous keys found on p. 27 of Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz, were used to determine the genus and species of the exuvia. Markers that match this specimen are highlighted in boldface green text. Three boldface green asterisks (***) are used to highlight the thread for identification of this specimen.

Key to the Genera of the Family Macromiidae

***1b. Lateral spines of abdominal segment 9 do not reach to rearward level of tips of inferior appendages [paraprocts]; Sides of head somewhat convergent behind eyes to pair of low turbercules on hind angles; Lateral setae of labium = 6; Small dorsal hook on segment 10. [Macromia]

A small dorsal hook on abdominal segment 10 is characteristic of Genus Macromia.

No. 3 | Macromia alleghaniensis | exuvia (dorsal-lateral)

Look closely at the full-size version of Image No. 4. Notice the little “nub” on abdominal segment 10 (S10), below the underside of the dorsal hook on abdominal segment nine (S9). The same structure is labeled with a white question mark in Image No. 3.

No. 4 | Macromia alleghaniensis | exuvia (dorsal-lateral)

The lateral spines of abdominal segment 9 (S9) do not reach rearward to the tips of the inferior appendages (paraprocts).

No. 5 | Macromia alleghaniensis | exuvia (dorsal)

Key to the Species of Macromia

1a. Lateral spines of abdominal segments 8 and 9 directed straight to rearward. [illinoiensis]

***1b. Lateral spines of abdominal segments 8 and 9 incurved, especially 8. [alleghaniensis]

The lateral spines of abdominal segments 8 and 9 (S8-9) are incurved, especially segment 8 (S8), indicating this species is alleghaniensis.

No. 6 | Macromia alleghaniensis | exuvia (ventral)

This individual is probably a male, as indicated by what appear to be vestigial hamules located on the ventral side of abdominal segments two and three (S2-3).

Summary

A prominent horn on the face is a key field marker for the Family Macromiidae (Cruisers), a small dorsal hook on abdominal segment 10 is one characteristic of the Genus Macromia, and the lateral spines of abdominal segments 8 and 9 (S8-9) are incurved, indicating the species is alleghaniensis. Therefore this specimen is an Allegheny River Cruiser dragonfly (Macromia alleghaniensis).

Bonus Gallery

No. 7 | Macromia alleghaniensis | exuvia (face-head)

No. 8 | Macromia alleghaniensis | exuvia (dorsal-lateral)

No. 9 | Macromia alleghaniensis | exuvia (dorsal)

Related Resources

Tech Tips

The following equipment was used to shoot Photo/Image No. 3-9: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode. Photo/Image No. 1 and 2Canon MP-E 65mm Macro lens (manual focus only, set for ~3x magnification) plus the multiple-flash setup.

Image No. 2-8 are focus-stacked composite images created and annotated using Adobe Photoshop CC 2017: Image No. 2 (eight photos); Image No. 3 (six photos); Image No. 4 (four photos); Image No. 5 (five photos); Image No. 6 (five photos); Image No. 7 (seven photos); Image No. 8 (seven photos).

Copyright © 2018 Walter Sanford. All rights reserved.

Macromiidae larvae/exuviae are horny

October 4, 2018

A prominent horn on the face is a key field marker for all larvae/exuviae in the Family Macromiidae (Cruisers).

The first image shows the top of the head of an exuvia from an Allegheny River Cruiser dragonfly (Macromia alleghaniensis), collected by Mike Boatwright on 07 June 2018 at Otter Lake in Amherst County, Virginia USA.

07 June 2018 | Amherst County, VA | exuvia (head-horn)

The next photo shows the top of the head of an Allegheny River Cruiser larva reared by fellow Virginian Bob Perkins, providing an excellent view of both the horn and antennae (2).

Image used with permission from Bob Perkins.

Tech Tips

The following equipment was used to shoot the composite image of the exuvia: Canon EOS 5D Mark II digital camera, in manual mode; Canon MP-E 65mm Macro lens (set for 3x); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode.

Adobe Photoshop CC 2017 was used to create the focus-stacked composite image from eight photos.

Bob Perkins’ photo of the larva, taken on 03 October 2018, was shot using a Canon EOS Rebel T3i camera body and Canon EF-S 60mm macro lens.

Copyright © 2018 Walter Sanford. All rights reserved.

Latest focus stacking workflow

October 2, 2018

I shot a small set of photos for a focus stack showing the ventral view of an unknown species of odonate exuvia. There are five “slices,” focused from head-to-tail along the body only (no shots focused on legs/feet).

The following gallery shows the five focus points along the body of the specimen, highlighted by a red square.

Although this photo set has fewer “slices” than I have been using to create focus stacks recently (~15-20 photos, on average), the resulting composite image (shown below) is perfectly in focus along the entire body and is serviceable for the purpose of identifying the genus and species of this specimen.

07 June 2018 | Amherst County, VA | exuvia (ventral)

The preceding composite image shows an exuvia from an unknown species of dragonfly (possibly River Cruiser sp.), collected by Mike Boatwright on 07 June 2018 at Otter Lake in Amherst County, Virginia USA. This individual probably is a male, as indicated by vestigial hamules located on the underside of abdominal segments two and three (S2-3).

Shooting the Photo Set

  • Set the camera for Manual Mode.
  • Set the lens for manual focus and turn off image stabilization (when the camera/lens is mounted on a tripod).
  • Compose the image so the frame is a little bigger than the scene you really want. This will give you some wiggle room during post-processing.
  • Set external flash(es) for Manual Mode. (~1/16 power is a good starting point.)
  • Select single focus point; move focus point around image.
  • Live View plus 5x and 10x magnification.
  • Drive mode: 10s timer.
  • DON’T MOVE THE CAMERA. Shoot as many images as necessary.

Advance Preparation – Edit Photos Using Aperture [or Lightroom]

Although Apple discontinued development of/support for Aperture years ago, the desktop application still works and in many ways I prefer Aperture over Adobe Lightroom.

  • Edit one image: make all adjustments except spot and patch, vignette, and BFX.
  • Right-click on edited photo; select “Lift Adjustments.”
  • <Replace> <Stamp Selected Images>
  • Add metadata: Lift and Stamp selected images.
  • Select images (to be focus stacked); export as TIFFs (16-bit), 300 dpi; save in folder entitled either “TIFF” or “TIFF versions.” File / Export… / Version… [Export Preset: TIFF – Original Size (16-bit)]

Focus Stacking Using Adobe Photoshop

Launch Photoshop.

  • File / Scripts / Load Files into Stack… [Alternate option: Add Open Files <OK>] Do not check the box for “Create Smart Object after Loading Layers.” By default, Ps creates a new document called “Untitled1.”
  • Select all layers.
  • Edit / Auto-Align Layers; Auto <OK>
  • Edit / Auto-Blend Layers; Stack Images, Seamless Tones and Colors <OK>
  • Duplicate all masked layers to a new document. Layer / Duplicate Layers… / Document: New / Name: Backup-copy
  • Select Untitled1: Layer / Merge Layers. (Ps merges all layers into one TIFF, named after first file in sequence.)
  • Straighten and Crop as necessary.
  • Duplicate the layer; append name with “Spot Healing.” [Alternate option: drag layer to copy icon]
  • Remove dust spots from the image: Spot Healing Brush: 27-54 pixels, Content-Aware.
  • Duplicate the layer; append name with “HPF.” [Alternate option: drag Spot Healing layer to copy icon]
  • Select the top layer: Filter / Other / High Pass…; adjust until you can just see outline of image <OK>; change Normal to Overlay. [Don’t oversharpen! ~2.6 used for the composite image featured in this blog post.]
  • Untitled1: Save As… TIFF.
  • Backup-copy (of masked layers): Save As… either PSD or Large Document Format (for documents larger than 2 GB).
  • Import composite TIFF file [Untitled1.tif] into Aperture [or Lightroom]: add additional keywords, as appropriate [e.g., annotated, composite image, focus stack, Photoshop]; Export using BorderBFX.

Tech Tips

The following equipment was used to shoot the composite image (shown above): Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode. A Sunpak LED-160 Video Light (with a white translucent plastic filter) was used to add soft light to the underside of the white “stage” used for posing the specimen.

Adobe Photoshop CC 2017 was used to create the focus-stacked composite image from five photos.

Copyright © 2018 Walter Sanford. All rights reserved.


%d bloggers like this: