Posts Tagged ‘terminal appendages’

Five Guys

November 16, 2017

Several Autumn Meadowhawk dragonflies (Sympetrum vicinum) were spotted along Easy Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. All of these individuals are male, as indicated by their terminal appendages.

Did you notice the preceding male appears to be missing his right hind wing? Perhaps I should rename this blog post “4.75 Guys.”

Editor’s Note: The photos in this gallery were taken a day before the first hard freeze in Northern Virginia that occurred overnight on Friday-Saturday, November 10-11. It will be interesting to see how many Autumn Meadowhawk dragonflies survived the record-setting low temperatures in the mid- to upper 20s.

Copyright © 2017 Walter Sanford. All rights reserved.

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Unambiguously Sympetrum ambiguum

November 10, 2017

Two Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum) were spotted during a photowalk along Charlie Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. Although Blue-faced Meadowhawk is on the species list of dragonflies and damselflies at Occoquan Bay NWR, this is the first time I have seen Sympetrum ambiguum at the refuge.

Male

This first individual is a male, as indicated by his terminal appendages.

19 OCT 2017 | OBNWR | Blue-faced Meadowhawk (male)

This guy was skittish. I was able to take one photo before he flew toward the tree canopy. The preceding photograph is what my good friend Mike Boatwright calls a “record shot,” that is, a photograph that records (verifies) my sighting of the male Sympetrum ambiguum. The photo was cropped slightly for improved composition.

Female

The last individual is a female heteromorph, as indicated by her tan coloration and terminal appendages.

The preceding photograph is my “record shot” of the female. I worked the shot…

…until I found the best viewpoint, shown below.

The first and last photos of the female were cropped slightly for improved composition; the second photo is uncropped.

Copyright © 2017 Walter Sanford. All rights reserved.

Lumix loves him some head-tilts!

November 6, 2017

An Autumn Meadowhawk dragonfly (Sympetrum vicinum) was spotted at Hidden Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages.

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 (below).

OK, so no head-tilt in the last photo, but I like the knot in the wooden dock on which the dragonfly is perching.

Tech Tips

The photographs in this gallery were taken using my Panasonic Lumix DMC-FZ150 superzoom digital camera set for ~24x zoom (focal length of 600mm, 35mm equivalent), and Canon 580EX Speedlite external flash (manual mode).

In order to reduce “camera shake,” the camera was set for shutter priority mode. Using the reciprocal rule, the shutter speed was set for 1/800s. The ISO was set for “100.” An inexpensive Sunpak 6700M aluminum monopod was used for added stability.

Copyright © 2017 Walter Sanford. All rights reserved.

Adding an 11mm extension tube

November 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 annotated table of magnification for the two extension tubes sold by Fujifilm USA.

Table courtesy Fujifilm USA.

Theory into practice

On 27 October 2017 several Autumn Meadowhawk dragonflies (Sympetrum vicinum) were spotted perching on the small dock at Hidden Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. All individuals featured in this photo gallery are male, as indicated by their terminal appendages.

All photos in this set were taken using my Fujifilm X-T1 digital camera, Fujinon XF55-200mm zoom lens, and a Fujifilm MCEX-11 extension tube. The camera was set for manual focus in order to use focus peaking; back-button focusing was used to focus automatically.

At 200mm, the working distance of the lens is 905 mm (90.5 cm, ~35.63 in), or approximately three (3) feet. With an 11mm extension tube mounted between the lens and camera body, the working distance is reduced to 665 mm (66.5 cm, ~26.2 in), or a little more than 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.

All of the following photos were slightly cropped for improved composition. The 11mm extension tube is the difference-maker that enables me to take close-up shots using a mid-range telephoto zoom lens such as the Fujinon 55-200mm.

ISO 640 | 200mm (~300mm, 35mm equivalent) | f/11 | 1/500s | -1 ev

ISO 640 | 200mm (~300mm, 35mm equivalent) | f/11 | 1/500s | -1 ev

When I changed the aperture from f/11 to f/16 (larger to smaller opening) for more depth-of-field, notice the ISO increased from 640 to 800. ISO was set for “Auto” with a limit of 800.

ISO 800 | 200mm (~300mm, 35mm equivalent) | f/16 | 1/500s | 0 ev

ISO 800 | 200mm (~300mm, 35mm equivalent) | f/16 | 1/500s | 0 ev

ISO 800 | 200mm (~300mm, 35mm equivalent) | f/16 | 1/500s | 0 ev

ISO 800 | 200mm (~300mm, 35mm equivalent) | f/16 | 1/500s | 0 ev

More tech tips

Focus peaking can be activated when the camera is set for manual mode. Using back-button focus (AF-L button) in manual mode enables one to retain full control of the exposure triangle, focus quickly, and see what’s in focus before shooting a photograph. Fuji Back Button Focus (4:06), a YouTube video by Ashraf Jandali, provides a clear demonstration of how to use back-button focus on the Fujifilm X-T1.

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 1/500s. In manual mode, I set the shutter speed and aperture; ISO was set for “Auto” with a limit of 800. An inexpensive Sunpak 6700M aluminum monopod was used for added stability.

Editor’s notes

Did you notice I didn’t use an external flash unit to shoot the preceding photos? The afternoon Sun is lower in the sky in late-October than it would be at the same time during mid-summer. I wanted to faithfully capture the shadows cast by the dragonflies in order to convey the feeling that the Sun is setting on these dragonflies, literally for the day as well as figuratively for the current odonate season.

Copyright © 2017 Walter Sanford. All rights reserved.

Like a bad guest at a party

October 31, 2017

Common Whitetail dragonflies (Plathemis lydia) are like bad guests at a party — they are among the first odonates to arrive in spring and among the last to leave in fall. Unlike bad guests, it’s good to see Common Whitetails after a long, cold winter and you have to admire the fact that they survived a long, hot summer.

22 OCT 2017 | HMP | Common Whitetail (mature female)

The preceding photograph shows a Common Whitetail dragonfly that was spotted near a vernal pool at a remote location in Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature female, as indicated by her terminal appendages and pattern of wing spots.

Copyright © 2017 Walter Sanford. All rights reserved.

Polymorphism or old age?

October 25, 2017

Some species of female odonates are polymorphic, meaning females can be one of two or more colors. In contrast, some species of female odonates become discolored with age.

The thorax and abdomen of female Autumn Meadowhawk dragonflies (Sympetrum vicinum) can be either tan or red. The difference in color is the result of either polymorphism or age-related discoloration. More research is required to establish cause and effect.

Several tan and red female Autumn Meadowhawks were spotted during a recent photowalk at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

Tan

This individual is a tan female, as indicated by her terminal appendages and noticeably thicker abdomen than males of the same species.

Red

The following individuals are red females.

Copyright © 2017 Walter Sanford. All rights reserved.

Great Spreadwing (practice oviposition)

October 15, 2017

This gallery — named “practice oviposition” (egg-laying) — features a six-photo time series of a female Great Spreadwing damselfly (Archilestes grandis).

Female Great Spreadwing damselflies, like all female odonates, have two cerci (sing. cercus), superior appendages that have little or no function. Also notice two styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition.

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

The female uses her styli to guide the ovipositor into position, as shown in the next two photos.

In this case, I saw no evidence that the ovipositor actually penetrated the tree twig. I think this was a practice run in preparation for the real thing, as the title of this blog post says.

Copyright © 2017 Walter Sanford. All rights reserved.

Great Spreadwing damselfly (female)

October 13, 2017

A Great Spreadwing damselfly (Archilestes grandis) was spotted near a vernal pool at a remote location in Huntley Meadows Park, Fairfax County, Virginia USA.

This individual is a female, as indicated by her terminal appendages and external reproductive anatomy, including two styli and an ovipositor.

Sometimes I struggle to choose between two similar images, so I decided to post both photos.

The following photo captured the “feel” of the morning light especially well.

The next two photos are among my favorites in this set.

This female was a more cooperative model after she moved to a perch on a man-made brush pile that provides habitat and shelter for many types of animals.

Female Great Spreadwing damselflies, like all female odonates, have two cerci (sing. cercus), superior appendages that have little or no function. Also notice two styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition.

My next blog post will feature a six-photo time series that I named “practice oviposition” (egg-laying).

Copyright © 2017 Walter Sanford. All rights reserved.

Blue-faced Meadowhawk dragonflies

October 9, 2017

“Target(s) acquired. Shots fired!” That’s my generic field report after a successful odonate hunting excursion. Usually I have an idea of the target species I hope to see every time I go photowalking. Shadow Darner dragonfly, Great Spreadwing damselfly, and Blue-faced Meadowhawk dragonfly were the target species for a recent trip to a favorite hotspot where all three types of odonates can be found.

Several Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum) were spotted near a vernal pool at a remote location in Huntley Meadows Park, Fairfax County, Virginia USA.

Both individuals featured in this blog post are male, as indicated by their terminal appendages and turquoise-colored faces.

Blue-faced Meadowhawk is classified as a fall species of odonate. In the mid-Atlantic United States, meadowhawks seem to disappear for several months after they emerge during early summer and reappear during fall. Where do they go? No one knows for sure. I speculate Blue-faced Meadowhawk is an arboreal species of dragonfly that returns to the ground/water when it’s time to mate.

Consistent with my speculation, Blue-faced Meadowhawk seems to prefer habitats where standing water is found near the forest, such as the small vernal pool located at a clearing in the forest at Huntley Meadows Park. Be on the lookout for Blue-faced Meadowhawk everywhere you find similar habitat.

Copyright © 2017 Walter Sanford. All rights reserved.

You know it’s fall when…

October 5, 2017

mature adult Autumn Meadowhawk dragonflies (Sympetrum vicinum) are seemingly everywhere there is water. Several Autumn Meadowhawks were spotted recently near a vernal pool at a remote location in Huntley Meadows Park (HMP), Fairfax County, Virginia USA.

The first individual is a male, as indicated by his terminal appendages.

03 OCT 2017 | HMP | Autumn Meadowhawk (male)

The last individual is a female, as indicated by her terminal appendages, noticeably thicker abdomen, and coloration.

03 OCT 2017 | HMP | Autumn Meadowhawk (female)

Autumn Meadowhawk is classified as a fall species of odonate. In the mid-Atlantic United States, meadowhawks seem to disappear for several months after they emerge during early summer and reappear during fall. Where do they go? No one knows for sure. I speculate Autumn Meadowhawk is an arboreal species of dragonfly that returns to the ground/water when it’s time to mate.

Related Resource: More previews of coming attractions, a blog post by Walter Sanford.

Copyright © 2017 Walter Sanford. All rights reserved.


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