Posts Tagged ‘Potomac River’

Cobra Clubtail dragonflies (females)

December 6, 2017

Male and female Cobra Clubtail dragonflies (Gomphurus vastus) are nearly identical in appearance except for their terminal appendages: females have two terminal appendages (cerci); males have three (claspers). Also notice the subtle difference in the shape of their hind wings: female hind wings are rounded; male hind wings are “indented.”

Several female Cobra Clubtails were photographed during the annual mass emergence along the Potomac River at Riverbend Park, Fairfax County, Virginia USA.

The first female, shown above, has a malformed wing.

Notice part of an insect leg on the wooden beam, underneath the female’s abdomen. Is it a leftover from a late-morning snack?

Copyright © 2017 Walter Sanford. All rights reserved.

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Incredible!

December 4, 2017

Odonates are aquatic insects. They spend most of their life as larvae that live in water; this stage of their life cycle can last from a few months to a few years. Finally, they emerge from the water and metamorphose into adults in order to reproduce; their offspring return to the water and the cycle begins again.

Careful and/or lucky observers will notice exuviae (sing. exuvia), also known as either “cast skins” or “shed skins,” left behind when odonate larvae emerge. Would you believe this…

metamorphosed into that? (See below.) It’s a miraculous transformation! The adult stage of the odonate life cycle can last from a week-or-so to a month-or-so, depending upon the species.

The first photo shows an exuvia from a Cobra Clubtail dragonfly (Gomphurus vastus), photographed in situ at Riverbend Park, Fairfax County, Virginia USA. All other photos in this gallery show adult male Cobra Clubtails, as indicated by their terminal appendages and “indented” hind wings.

Copyright © 2017 Walter Sanford. All rights reserved.

Reminiscing

December 2, 2017

As I was reminiscing about the annual mass emergence of Cobra Clubtail dragonflies (Gomphurus vastus) along the Potomac River at Riverbend Park, Fairfax County, Virginia USA, I realized there are lots of photos shot in May 2017 that were never edited.

This photo set features a female perching on colorful kayaks in a storage rack near the boat ramp. Both photos are uncropped, that is, they are full-size images (4,000 x 3,000 pixels).

Related Resource: Because it’s fun, a blog post featuring photos of a male Cobra Clubtail (perching on the same kayaks) shot on the same day using my Fujifilm X-T1 digital camera.

Copyright © 2017 Walter Sanford. All rights reserved.

Exuviart

August 22, 2017

Regular readers of my blog remember when I coined the term “Odonart” and created an “Odonart Portfolio.”

I just coined a new term: “Exuviart.” Exuviart is a concatenation of two words: exuvia; and art. The following photographs are the first additions to the Exuviart wing of my Odonart Portfolio.


Unpublished Photo

An Eastern Amberwing dragonfly (Perithemis tenera) exuvia, from the Family Libellulidae (Skimmers), was collected from the Potomac River in Fairfax County, Virginia USA.

Whenever possible, I like to collect exuviae along with some of the vegetation that was the site for emergence. The vegetation helps to show scale. In this case, the small specimen is approximately 1.4 cm (~0.6″) in length and approximately 0.6 cm (~0.2″) in maximum width. I like the way the desiccated leaf retained its color and gained a velvety texture.

Tech Tips

The following equipment was used to shoot the preceding photograph: Canon EOS 5D Mark II DSLR; Canon EF100mm f/2.8 Macro lens plus Raynox DCR-250 close-up filter; Canon 580EX II Speedlite; Canon 580EX Speedlite; and a coiled six-foot Vello Off-Camera TTL Flash Cord for Canon Cameras. The specimen was staged on a piece of white plastic (12″ square, matte finish).


Published Photos

A Common Green Darner dragonfly (Anax junius) exuvia, from the Family Aeshnidae (Darners), was collected at Hidden Pond, Meadowood Recreation Area (MRA), Fairfax County, Virginia USA.

Tech Tips

The following equipment was used to shoot the preceding photograph: Canon EOS 5D Mark II digital camera, in manual mode; Canon EF100mm f/2.8L Macro lens (set for manual focus); Canon 580EX II external flash, off-camera, in manual mode; Canon 580EX external flash, off-camera, in manual mode; and a Yongnuo YN-622C-TX E-TTL II Wireless Flash Controller for Canon plus a two-pack of Yongnuo YN-622C II E-TTL Wireless Flash Transceivers for Canon.


A Cobra Clubtail dragonfly (Gomphurus vastus) exuvia, from the Family Gomphidae (Clubtails), was collected at Riverbend Park with permission from park staff.

Tech Tips

The following equipment was used to shoot the preceding photograph: Canon EOS 5D Mark II digital camera, in manual mode; Canon EF100mm f/2.8L Macro lens (set for manual focus) plus a Kenko 20mm macro automatic extension tube and Raynox DCR-250 close-up filter; Canon 580EX II external flash, off-camera, in manual mode; Canon 580EX external flash, off-camera, in manual mode; and a Yongnuo YN-622C-TX E-TTL II Wireless Flash Controller for Canon plus a two-pack of Yongnuo YN-622C II E-TTL Wireless Flash Transceivers for Canon.

Copyright © 2017 Walter Sanford. All rights reserved.

Powdered Dancer (males, female)

August 20, 2017

A Powdered Dancer damselfly (Argia moesta) was spotted during a photowalk along a mid-size rocky stream in Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages. There is a whitish-blue morph female Powdered Dancer, therefore the male’s whitish-blue coloration is insufficient to identify its gender.

21 JUN 2017 | Fairfax County, VA | Powdered Dancer (male)

A week later, a mating pair of Powdered Dancers was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This pair is “in tandem“: the male is on the upper-left; the female on the lower-right.

28 JUN 2017 | Riverbend Park | Powdered Dancers (mating pair, in tandem)

The male is “contact guarding” the female as the pair flies “in tandem” to egg-laying sites where the female uses her ovipositor to insert eggs into vegetation (endophytic oviposition).

It’s helpful to take photos of mating pairs of damselflies, especially “in tandem,” since males and females of the same species can look quite different.

Female Powdered Dancers are polymorphic, including a whitish-blue andromorph and a brown heteromorph. The brown morph, shown in this pair, is more common than whitish-blue.

28 JUN 2017 | Riverbend Park | Powdered Dancers (mating pair, in tandem)

Did you notice the male Stream Bluet damselfly (Enallagma exsulans) perching near the Powdered Dancers? Thanks to Karen Kearney and Michael Boatwright, members of the Virginia Odonata Facebook group, for confirming my tentative identification of the Stream Bluet.

Copyright © 2017 Walter Sanford. All rights reserved.

Adding a 16mm extension tube

August 2, 2017

Optics theory

The net effect of adding an extension tube between a lens and camera body is the “working distance” is decreased, that is, the distance from the front of the lens barrel to the subject is decreased. A smaller working distance means the same lens will focus closer to the subject, thereby increasing magnification.

The effect is greater at shorter focal lengths, as shown by the following table of magnification for the two extension tubes sold by Fujifilm USA.

Table courtesy Fujifilm USA.

Theory into practice

An Eastern Ringtail dragonfly (Erpetogomphus designatus) was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a female, as indicated by her terminal appendages and rounded hind wings.

Both photos in this set were taken using my Fujifilm X-T1 digital camera, Fujinon XF55-200mm zoom lens plus a “Fotasy” brand 16mm extension tube, and Fujifilm EF-X500 shoe mount flash. The lens was set for a focal length of 200mm (~300mm, 35mm equivalent).

At 200mm, the working distance of the lens is 905 mm (90.5 cm, ~35.63 in), or approximately three (3) feet. With a 16mm extension tube mounted between the lens and camera body, the working distance is reduced to 595 mm (59.5 cm, ~23.43 in), or approximately two (2) feet. At a focal length of 55mm, adding the extension tube would result in photos that look more like “macro” photos; at 200mm, adding the extension tube resulted in photos that look like a lens with a longer focal length was used to take the shots.

The first photo is uncropped. I’ve never been able to get a shot like this using a mid-range telephoto zoom lens such as the Fujinon 55-200mm. The 16mm extension tube is the difference-maker.

The last photo is cropped slightly, but not enough to affect the apparent magnification. I look closely at the edges of my photos. In this case, I cropped the photo to remove some distracting elements and leading lines.

Editor’s Notes

I bought a set of two “Fotasy” brand extension tubes (10mm, 16mm) years before Fujifilm released their set of two. The advantage of the Fotasy extension tubes is a set of two costs a little more than half as much as a single Fujifilm extension tube. The disadvantage is compatibility. The Fotasy extension tubes work with my Fujinon XF18-55mm (27-82.5mm, 35mm equivalent) “kit” lens and Fujinon XF55-200mm mid-range telephoto zoom lens; they don’t work with my Fujinon XF100-400mm (152-609mm, 35mm equivalent) telephoto zoom lens. For what it’s worth, the 100-400mm lens was released after the Fotasy extension tubes. Bottom line: I recommend Fujifilm extension tubes, despite the fact that they are significantly more expensive than Fotasy extension tubes.

The Depth of Field is razor thin, in contrast with shooting without an extension tube. I shot the preceding photos at f/11; f/16 or smaller would have been better.

In order to reduce “camera shake,” I almost always shoot in shutter priority mode using the reciprocal rule. Remember, it’s the 35mm equivalent that matters: since my lens is ~300mm, the shutter speed should be set for at least 1/300s; in this case, it was set for 1/1,000s. A monopod was used for added stability.

Copyright © 2017 Walter Sanford. All rights reserved.

Eastern Ringtail dragonfly (female)

July 21, 2017

An Eastern Ringtail dragonfly (Erpetogomphus designatus) was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a female, as indicated by her terminal appendages and rounded hind wings.

(See a full-size version of the original photo, without annotation.)

I saw tens of male Eastern Ringtail, but only one female.

The preceding photograph is my favorite in the set. I like the way the neutral colors in the pavement complement the coloration of the female.

Copyright © 2017 Walter Sanford. All rights reserved.

“Big Boy”

July 19, 2017

Several Eastern Ringtail dragonflies (Erpetogomphus designatus) were spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. These individuals are male, as indicated by their terminal appendages and “indented” hind wings.

All of the photos in this set were taken using my Fujifilm X-T1 digital camera, Fujinon 100-400mm telephoto zoom lens, and Fujifilm EF-X500 shoe mount flash.

I nicknamed the Fujinon 100-400mm lens “Big Boy” because it’s so big and heavy. I use a Sunpak 6700M monopod and Vanguard SBH 100 ball head to support the lens.

Zoom in on the full-size version of the preceding photo. Notice the terminal appendages are spread apart, revealing a clear look at both the cerci and hook-shaped epiproct.

Related Resource: You complete me – a blog post published on 19 February 2016 in which I shared my first impressions of the Fujinon 100-400mm telephoto zoom lens.

Copyright © 2017 Walter Sanford. All rights reserved.

Eastern Ringtail dragonflies (more males)

July 17, 2017

Many Eastern Ringtail dragonflies (Erpetogomphus designatus) were spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. All of the individuals in this gallery are male, as indicated by their terminal appendages and “indented” hind wings.

Please look at the full-size version of each photo in order to appreciate the coloration of these handsome male dragonflies.

Copyright © 2017 Walter Sanford. All rights reserved.

Eastern Ringtail dragonflies (males)

July 15, 2017

Tens of Eastern Ringtail dragonflies (Erpetogomphus designatus) were spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. Both individuals featured in this post are male, as indicated by their terminal appendages and “indented” hind wings.

Regular readers of my photoblog know I’m fond of head-tilts in which the dragonfly seems to display some of its personality, especially when the individual is looking at me. Like the male featured in the following photo — one of my all-time favorites!

In my opinion, the unique coloration of Erpetogomphus designatus rivals Genus Ophiogomphus (Snaketails). There, I said it!

Copyright © 2017 Walter Sanford. All rights reserved.


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