Posts Tagged ‘Family Libellulidae (Skimmers)’

Blue Dasher dragonfly (female)

July 8, 2020

Behold the humble Blue Dasher dragonfly (Pachydiplax longipennis). So common, yet so uncommonly attractive in its own way.

13 JUN 2020 | Fairfax County, VA | Blue Dasher (female)

This individual is a female, as indicated by her terminal appendages. Initially I thought she might be another species of dragonfly, due to her somewhat atypical coloration.

13 JUN 2020 | Fairfax County, VA | Blue Dasher (female)

The Backstory

During a recent photowalk with Michael Powell at a location in Fairfax County, Virginia USA, we were men on a mission to find three rare to uncommon species of dragonflies: Arrowhead Spiketail (Cordulegaster obliqua); Gray Petaltail (Tachopteryx thoreyi); and Sable Clubtail (Stenogomphurus rogersi).

Albeit common, and not one of our target species, sometimes you need to stop and smell the Blue Dashers, figuratively speaking.

As for our list of target species, let’s just say two out of three ain’t bad.

Copyright © 2020 Walter Sanford. All rights reserved.

Widow Skimmer dragonfly (female)

June 15, 2020

How can you tell when a photographer is nearly as persistent as a dragonfly is skittish? Every photo in this blog post shows the subject against a different background!

The following Widow Skimmer dragonfly (Libellula luctuosa) was spotted during a recent photowalk with Michael Powell at a location in Fairfax County, Virginia USA.

08 JUN 2020 | Fairfax County, VA | Widow Skimmer (female)

This individual is a female, as indicated by her coloration, pattern of wing spots, and terminal appendages.

08 JUN 2020 | Fairfax County, VA | Widow Skimmer (female)

The camera was set for Manual exposure using an aperture of f/6.3 and a shutter speed of 1/800 s. I knew the depth-of-field would be too shallow to show the subject in focus from head to tail, but I took the shot anyway because I wanted a good photo of her face plus it’s uncommon to get a look at the ventral side of a perched dragonfly.

08 JUN 2020 | Fairfax County, VA | Widow Skimmer (female)

Habitat

Information regarding the preferred habitat for Widow Skimmer can be found by following the hyperlinks to authoritative references embedded in this post, including Dragonflies of Northern Virginia, BugGuide, and The Dragonflies and Damselflies of North Carolina.

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

Icebreaker

June 8, 2020

When I go looking for rare-to-uncommon species of odonates, I like to take a few “warm-up shots” at the beginning of the photowalk in order to be sure all my photography gear is working properly — the moment you find your target species is the wrong time to be fiddling around with camera settings or troubleshooting an external flash unit that isn’t firing!

The following photo is one of my “warm-up shots” from a recent photowalk with Michael Powell at a location in Fairfax County, Virginia USA.

26 MAY 2020 | Fairfax County, VA | Common Whitetail (immature male)

Common Whitetail (Plathemis lydia) is a common species of dragonfly. Plathemis lydia is a “habitat generalist” that can be found almost anywhere there is water. It is one of the first species to appear in spring and one of the last species to disappear in fall.

This individual is an immature male, as indicated by the brown coloration of his abdomen, pattern of wing spots, and terminal appendages.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Focus Stacking using Adobe Photoshop

April 1, 2020

The following tutorial provides step-by-step instructions that can be used to create focus-stacked composite images with Adobe Photoshop (Ps).

First, download (from Google Drive) the two 16-bit TIFF files that will be focus-stacked. One photo is focused on the thorax, near the left eye; the other photo is focused on abdominal segment eight (S8).

Save the files to a folder on the desktop of your computer.

Open Photoshop.

  1. File / Scripts / Load Files into Stack… [Navigate to the folder on your desktop and select both files. By default, Ps creates a new document called “Untitled1.”]
  2. Select all layers. [Click on filenames, not icons.]
  3. Edit / Auto-Align Layers; Auto <OK>
  4. Edit / Auto-Blend Layers; Stack Images, Seamless Tones and Colors <OK>
  5. Duplicate layers to a new document. Layer / Duplicate Layers… / Document: New / Name: Backup-copy]
  6. Select “Untitled1”: Layer / Merge Layers (Ps merges all layers into one TIFF, named after the first file in sequence.)
  7. Straighten and Crop as necessary.
  8. Duplicate layer; append name with “Spot Healing.” [Remove dust spots, etc. from image using either Spot Healing Brush (Content-Aware) or Edit/Fill (Content Aware).
  9. “Sharpen” image. Duplicate top layer; append name with “HPF.” [Select top layer: Filter / Other / High Pass…; adjust until you can just see outline of image <OK>; change Normal to Overlay. 1.5 is a good starting point; decrease/increase as necessary. DO NOT OVERSHARPEN!
  10. File / Save As… TIFF; JPG.
  11. Select “Backup-copy.” File / Save As… Photoshop.

The composite image that you created should look like this, not including the copyright information shown in the lower-left corner of my image.

Take-aways

A two-photo focus stack works in part because the photos were shot using an aperture of f/16. Usually more than two “layers” are required to create a satisfactory focus-stacked composite image.

The same workflow can be used to create focus stacks using more layers with one caveat: more layers take more time for Photoshop to process.

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Anisoptera exuvia (species unknown)

March 11, 2020

An Anisoptera exuvia (species unknown) was collected near a small pond at Occoquan Regional Park (ORP), Fairfax County, Virginia USA.

This individual probably is a member of the Family Libellulidae (Skimmers), as indicated by its anal pyramid. The small pond where the specimen was collected is perfect habitat for skimmers.

01 JUN 2019 | ORP | Anisoptera exuvia (dorsallateral view)

Related Resource: Another unknown species of odonate exuvia – a blog post by Walter Sanford featuring a “one-off” photo (that is, not a composite image) of the same specimen.

Tech Tips

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

Two photos were used to create a composite image: one photo focused on the head; and another photo focused on abdominal segments seven (S7) through nine (S9).

My Canon EOS 5D Mark II is a full-frame DSLR digital camera. RAW images are 5616 × 3744 pixels. The dimensions of the composite image are 5589 × 3743 pixels, that is, essentially full-frame. It’s usually necessary to crop composite images, at least a little, because the individual photos used to create the composite don’t align perfectly, even when the camera is mounted on a tripod (as it was in this case).

For what it’s worth, the following camera settings were used to shoot both photos: 100mm; ISO 100; f/8; 1/200 s; 0 ev. I need to tweak the settings a little in order to find the “sweet spot” for this camera/lens combo: the white background was slightly over-exposed; and the subject was slightly under-exposed. Of course that means I need to tweak the flash power for the backlights and add one or more additional external flash units for more fill flash. Overall, I’m fairly satisfied with the results of my first attempt using the MYN technique with this camera rig.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Eastern Amberwing exuvia (anal pyramid)

March 9, 2020

An Eastern Amberwing dragonfly (Perithemis tenera) exuvia was collected by Joe Johnston on 07 August 2019 along Aquia Creek at Channel Marker No. 34, Stafford County, Virginia USA.

The specimen is probably from either Family Corduliidae (Emeralds) or Family Libellulidae (Skimmers).

The rule of thumb for differentiating Corduliidae exuviae from Libellulidae is as follows: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts; it’s probably Libellulidae if the cerci are less than half the length of the paraprocts.

65mm (3x magnification) | ISO 100 | f/8 | 1/200 s | 0 ev

Look closely at the full-size version of the preceding photo, showing a close-up of the anal pyramid at 3x magnification. Notice the cerci are approximately half as long as the epiproct and slightly less than half the length of the paraprocts. It’s a close call, but the latter field mark indicates Family Libellulidae (Skimmers).

A step-by-step identification guide (to the species level) will be published in a follow-up post. Stay tuned!

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Unknown dragonfly exuvia (redux)

February 26, 2020

This blog post features more photos of an exuvia from an unknown species of odonate that was collected by Joe Johnston on 07 August 2019 along Aquia Creek at Channel Marker No. 34, Stafford County, Virginia USA.

The specimen is probably from either Family Corduliidae (Emeralds) or Family Libellulidae (Skimmers).

07 AUG 2019 | Aquia Creek | dragonfly exuvia (dorsal view)

The rule of thumb for differentiating Corduliidae exuviae from Libellulidae is as follows: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts; it’s probably Libellulidae if the cerci are less than half the length of the paraprocts.

07 AUG 2019 | Aquia Creek | dragonfly exuvia (ventral view)

I’m having a hard time seeing the cerci clearly. If I’m seeing what I think I’m seeing, then the cerci are at least half as long as the paraprocts and the exuvia is from Family Corduliidae (Emeralds).

In order to verify my tentative identification, I need to use a higher magnification macro lens (such as my Canon MP-E 65mm Macro lens) in order to shoot a close-up view of the anal pyramid/terminal appendages (see inset diagram, lower-left corner).

Related Resource: MYN – Dragonfly exuvia (unknown species)

Tech Tips

This specimen was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. I used the new variation on my old MYN studio rig and I’m still satisfied with the results.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Tramea sp. exuvia (ventral)

February 3, 2020

An odonate exuvia, collected by Andy Davidson near Richmond, Virginia USA, was photographed against a pure white background using the “Meet Your Neighbours” (MYN) technique. Two photos were used to create a composite image: one photo focused on the prementum; and another photo focused on abdominal segment eight (S8).

This individual is from the Genus Tramea (Saddlebags), in the Family Libellulidae (Skimmers). Since it’s nearly impossible to differentiate exuviae from the Genus Tramea to the species level, we’ll leave its identity as Tramea sp. It’s the same specimen featured in my last three blog posts: MYN – Tramea sp. exuvia (face-head-dorsal)MYN – Tramea sp. exuvia (dorsal); MYN – Tramea sp. exuvia (dorsal-lateral).

Tech Tips

The subject was photographed against a pure white background using the “Meet Your Neighbours” (MYN) technique. The exuvia was “staged” on a clear plastic surface raised ~1.5 in (~3.81 cm) above the white background.

The dorsal side of the specimen was lying on the clear plastic. The “eyes” were closer to the light source than all other photos/composite images in a four-part series of this subject; as a result, the eyes look washed out. I know from experience that problem can be solved by moving the clear plastic stage farther from the white background.

In this case, I was less concerned about showing the eyes in their best light and more concerned about looking for signs of sex organs that indicate gender. I don’t see anything that looks like either vestigial genitalia (male) or a rudimentary ovipositor (female).

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Tramea sp. exuvia (dorsal-lateral)

January 31, 2020

An odonate exuvia, collected by Andy Davidson near Richmond, Virginia USA, was photographed against a pure white background using the “Meet Your Neighbours” (MYN) technique. Two photos were used to create a composite image: one photo focused on the thorax, near the left eye; and another photo focused on abdominal segment eight (S8).

This individual is from the Genus Tramea (Saddlebags), in the Family Libellulidae (Skimmers). Since it’s nearly impossible to differentiate exuviae from the Genus Tramea to the species level, we’ll leave its identity as Tramea sp. It’s the same specimen featured in my last two blog posts: MYN – Tramea sp. exuvia (face-head-dorsal); MYN – Tramea sp. exuvia (dorsal).

What are the take-aways?

I have been wondering whether the MYN technique could be used to create focus-stacked composite images. Wonder no more — it works and the results are worth the extra effort.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Tramea sp. exuvia (face-head-dorsal)

January 29, 2020

An odonate exuvia, collected by Andy Davidson near Richmond, Virginia USA, was photographed against a pure white background using the “Meet Your Neighbours” (MYN) technique.

This individual is from the Genus Tramea (Saddlebags), in the Family Libellulidae (Skimmers). Since it’s nearly impossible to differentiate exuviae from the Genus Tramea to the species level, we’ll leave its identity as Tramea sp. It is the same specimen featured in my last blog post.

Tramea sp. | exuvia (face-head-dorsal)

Related Resource: Tramea carolina exuvia.

Tech Tips

The subject was photographed against a pure white background using the “Meet Your Neighbours” (MYN) technique. The exuvia was “staged” on a clear plastic surface raised ~1.5 in (~3.81 cm) above the white background.

If you look at the “Categories” shown below this blog post, then you will see three external flash units listed: Canon MT-26EX-RT Macro Twin Lite; Godox TT685C; and Godox TT685F. In fact, either one or two flashes at a time are used during a typical MYN photoshoot. The Godox TT685C is always on; it’s used to backlight the white plastic background. Sometimes the TT685C is the only flash that fires; other times I will use either the Canon Macro Twin Lite or Godox TT685F for fill flash.

Although the EXIF Info says “Flash fired” there is no way to tell which flash(es) fired and their power ratio(s). In a way, that’s a good thing because it forces me to pick the best image from a set of photos regardless of how many flashes were used to light the subject. In this case, the Godox TT685C was set for a power ratio of 1/2 +0.3 power; the Godox TT685F was set for 1/256; and the Canon Macro Twin Lite was set for 1/512.

More information about both the photo gear that I used to shoot this photo, as well as detailed practical advice for using the MYN technique is available in the following blog post: MYN – Hagenius brevistylus exuvia (dorsal).

Copyright © 2020 Walter Sanford. All rights reserved.


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