Archive for the ‘natural science’ Category

Test shots: Pachydiplax longipennis exuvia

November 19, 2018

A Blue Dasher (Pachydiplax longipennis) exuvia was received from Andy Davidson, a graduate student at Virginia Commonwealth University.

Test shots of the specimen were taken using a relatively small aperture of f/20 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 posed for better composition.

Extremely shallow depth-of-field is a common problem in macro photography. Depth-of-field increases as aperture decreases — in other words, they are inversely related. In this case, an aperture of f/20 was insufficient for the entire subject to be acceptably in focus so it will be necessary to create some focus stacks.

Also notice the background of the second photo looks darker and bluer than the first one. That was caused by the fact that the subject was farther from the front of the lens. There are work-arounds for this lighting problem, but hey, like the title of this blog post says these are “test shots.”

Related Resources

Tech Tips

The following equipment was used to shoot both of the macro photographs featured in this post: Fujifilm X-T1 digital camera; Fujifilm MCEX-11 extension tube; and Fujinon XF80mm macro lens. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Actually, back-button focus was used to autofocus the image and adjusted manually as necessary. That’s also a Fujifilm thing. For details, see “More Tech Tips” (below).

Godox XProF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control a pair of off-camera Godox TT685 Thinklite TTL Flashes(TT685F and TT685C) set for radio slave mode. Each flash was fitted with a snap-on plastic diffuser.

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

Copyright © 2018 Walter Sanford. All rights reserved.

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Test shots: Erythemis simplicicollis exuvia

November 16, 2018

An Eastern Pondhawk (Erythemis simplicicollis) exuvia was received from Andy Davidson, a graduate student at Virginia Commonwealth University.

This individual is a male, as indicated by the vestigial hamules visible on the ventral side of the exuvia, abdominal segments two and three (S2-S3).

Food for Thought

This exuvia is one of three “cast skins” from odonate nymphs that were collected in the field and reared in the laboratory as part of a research project entitled “Predator-Prey Interactions in a Changing World.” Since all three nymphs were collected from the James River rock pools, I assume they lived in essentially the same habitat. I wonder why the E. simplicollis exuvia is so much darker in color than either the P. flavescens or P. longipennis exuviae.

Related Resources

Tech Tips

The following equipment was used to shoot both of the macro photographs featured in this post: Fujifilm X-T1 digital camera; Fujifilm MCEX-11 extension tube; and Fujinon XF80mm macro lens. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Actually, back-button focus was used to autofocus the image and adjusted manually as necessary. That’s also a Fujifilm thing. For details, see “More Tech Tips” (below).

Godox XProF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control a pair of off-camera Godox TT685 Thinklite TTL Flashes(TT685F and TT685C) set for radio slave mode. Each flash was fitted with a snap-on plastic diffuser.

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

Copyright © 2018 Walter Sanford. All rights reserved.

Test shots: Pantala flavescens exuvia

November 14, 2018

A Wandering Glider (Pantala flavescens) odonate exuvia was received from Andy Davidson, a graduate student at Virginia Commonwealth University in Richmond, Virginia USA. Sincere thanks to Andy for sharing this beautiful specimen!

The exuvia is a “cast skin” from a nymph that was collected in the field and reared in the laboratory as part of a research project entitled “Predator-Prey Interactions in a Changing World.”

Test shots of the 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 posed for better composition.

Related Resources

Tech Tips

The following equipment was used to shoot both of the macro photographs featured in this post: Fujifilm X-T1 digital camera; Fujifilm MCEX-11 extension tube; and Fujinon XF80mm macro lens. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Actually, back-button focus was used to autofocus the image and adjusted manually as necessary. That’s also a Fujifilm thing. For details, see “More Tech Tips” (below).

Godox XProF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control a pair of off-camera Godox TT685 Thinklite TTL Flashes (TT685F and TT685C) set for radio slave mode. Each flash was fitted with a snap-on plastic diffuser.

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

More Tech Tips

Focus peaking can be activated when the camera is set for manual focus 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.

Copyright © 2018 Walter Sanford. All rights reserved.

Common Five-lined Skink

November 9, 2018

A Common Five-lined Skink (Plestiodon fasciatus) was spotted during a photowalk at Occoquan Regional Park, Fairfax County, Virginia USA.

This individual is a juvenile as indicated by its dark brown color and bright blue tail.

Copyright © 2018 Walter Sanford. All rights reserved.

Bonding with Bender

November 7, 2018

Gray Petaltail dragonflies (Tachopteryx thorei) have a well-known preference for perching on gray or tan colored surfaces, including gray or tan colored clothing. Dressed appropriately, I visited a hotspot for Gray Petaltail where I hoped to shoot some “selfie” photographs of a Grey Petaltail perched on me.

The first photo is a “selfie” that shows a Fiery Skipper butterfly (Hylephila phyleus) perched on my left forearm. Thanks to several members of the BugGuide Facebook group for help in identifying the butterfly!

A Fiery Skipper butterfly perched on my left forearm.

The pained expression on my face says “You should have worn your glasses, you old fool!” I call it “going snake-eyed.”

The last photo is a “selfie” that shows a Gray Petaltail dragonfly perched on my Cabela’s Safari Series vest. This individual is a male that I nicknamed “Bender” because of his malformed abdomen.

A Gray Petaltail dragonfly (male) perched on my Cabela’s safari vest.

Open the full-size version of the preceding photo and zoom in on the dragonfly. Look at Bender’s face. I wonder what he was thinking.

Tech Tips

I used my Panasonic Lumix DMC-FZ150 superzoom camera to shoot the “selfie” photos featured in this blog post. The camera was set for manual focus at the hyperfocal distance for an aperture of f/4, based upon the instructions provided in the excellent video tutorial by Graham Houghton, “Panasonic Lumix FZ camera easier manual focus method — super point-and-shoot tip.”

The camera was mounted on a Sunpak 8001 UT medium duty aluminum tripod, with the articulating LCD facing forward. A JJC TM-Series Multi-Function Timer Remote Control was connected to the camera. I sat on a Coleman camp stool positioned a few feet in front of the camera, with the remote control in one hand.

Copyright © 2018 Walter Sanford. All rights reserved.

Precious cargo

November 5, 2018

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. Exuviae are fragile little works of natural art that are challenging at best to ship from one location to another.

The preceding photo shows a small plastic vial containing three odonate exuviae, received from Andy Davidson. All three exuviae are members of Family Libellulidae (Skimmers). From left-to-right, the following specimens can be seen inside the vial: Wandering Glider (Pantala flavescens); Eastern Pondhawk (Erythemis simplicicollis); Blue Dasher (Pachydiplax longipennis).

Andy packed the exuviae carefully inside a centrifuge tube with a screw on/off cap; pieces of crumpled bubble wrap were used to separate the specimens inside the tube. A pair of tweezers was used to remove the bubble wrap. All three exuviae appear to be in perfect condition.

Editor’s Notes

Andy Davidson is a graduate student at Virginia Commonwealth University in Richmond, Virginia USA. Andy works with Dr. James Vonesh, his faculty advisor, and a team of researchers studying the ecology of James River rock pools. Andy’s research project is entitled “Predator-Prey Interactions in a Changing World.”

Sincere thanks to Andy for kindly sharing several exuviae saved from laboratory-reared odonate nymphs — I’m looking forward to creating new annotated identification guides for the specimens!

Copyright © 2018 Walter Sanford. All rights reserved.

Powell’s Place

November 2, 2018

A single Sable Clubtail dragonfly (Stenogomphurus rogersi) was spotted perched alongside a small stream located in Fairfax County, Virginia USA.

I nicknamed a segment of the stream “Powell’s Place” in honor of Mike Powell, my good friend and photowalking buddy, who spotted the first Sable observed at this part of the stream. “Powell’s Place” is located downstream from Hotspot No. 1, where the stream re-emerges from an underground concrete pipe.

This individual is a male, as indicated by his indented hind wings and terminal appendages. Some dragonflies tend to be creatures of habit, returning to the same spot day-after-day. Perhaps this is the same individual spotted by Mike. Who knows?

I like the juxtaposition of complementary colors in the first photo.

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

The next photo shows the dragonfly perched deep within a shaded hidey-hole.

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

The last photo is a contender for my Odonart Portfolio.

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

Full disclosure: Adobe Photoshop was used to removed a tiny distracting element from the bottom-right half of the preceding image (the point of a single blade of grass).

Copyright © 2018 Walter Sanford. All rights reserved.

Beetlejuice

October 31, 2018

Look closely at the following photograph and ask yourself “What’s wrong with this picture?”

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

Did you notice the dragonfly’s head is turned upside-down? That reminds me of the movie Beetlejuice (1988). Happy Halloween!

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

All three photos show the same Sable Clubtail dragonfly (Stenogomphurus rogersi), perched alongside a small stream located in Fairfax County, Virginia USA. This individual is a male, as indicated by his indented hind wings and terminal appendages. Notice his head is upside-up in the last two photos.

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

Related Resource: Cobra Clubtail head-tilts, featuring a female with her head positioned nearly upside-down. I guess the upside-down head thing is characteristic of some members of Family Gomphidae (Clubtails).

Copyright © 2018 Walter Sanford. All rights reserved.

Hotspot No. 2

October 29, 2018

The Backstory

A small population of Sable Clubtail dragonflies (Stenogomphurus rogersi) was observed along three segments of a tiny stream located in Fairfax County, Virginia USA. I named the segments Hotspot No. 1, Hotspot No. 2, and “Powell’s Place.”

Hotspot No. 1 is the place where I saw my first Sable Clubtail. At least five individuals, all males, were observed by the author at this location. To date, almost all of the photos of Sable that have been published in this blog were taken at Hotspot No. 1.

Hotspot No. 2 is located upstream from Hotspot No. 1, near one of several seeps that feed the creek. This is the location where a female Sable Clubtail was spotted on 05 July 2018. As it turn out, that female was the last Sable spotted during 2018.

Powell’s Place” is located downstream from Hotspot No. 1, where the stream re-emerges from an underground concrete pipe. “Powell’s Place” is named for Mike Powell, my good friend and photowalking buddy, who spotted the first Sable observed at this segment of the stream. A related blog post will be published on Friday, 02 November 2018.

Hotspot No. 2

One or more male Sable Clubtail dragonflies were observed and photographed on 12 June 2018 at this location.

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

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

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

Copyright © 2018 Walter Sanford. All rights reserved.

Do-over

October 24, 2018

The Backstory

An Ashy Clubtail dragonfly (Phanogomphus lividusnymph was collected by Bob Perkins. (The date and location where the specimen was collected are unknown.) The nymph was reared in captivity until it emerged on 21 March 2017 and metamorphosed into an adult female. This specimen is the exuvia from the nymph. P. lividus is a member of the Family Gomphidae (Clubtails).

A focus-stacked composite image was created from 39 photos focused on the face and head of the exuvia. I had relatively little experience using Adobe Photoshop to make focus stacks when I created the first iterations of the Ashy Clubtail composite image. I was never satisfied completely with the final output, so I decided to do a do-over.

After…

The updated version of the composite image was created using my “Latest focus stacking workflow.”

Before…

The version that I published in late-March 2018 was created using the RAW photos (CR2) from my Canon digital camera, without any post-processing. I tried to adjust the white balance and color palette of the resulting composite image, but was unable to get the “look” I wanted. The image is probably over-sharpened too.

Which version do you prefer?

I know the version I like more. Which do you prefer, After or Before?

Tech Tips

The preceding images are composites of 39 photos taken using the following equipment: Canon EOS 5D Mark II digital camera, in manual mode; Canon MP-E 65mm Macro lens (manual focus only, set for 3x magnification); and 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 focus stack the photos and post-process the final output.

According to the “Focus Stacking Step Size Calculator” embedded in the “Focus Stacking” Web page, the “safe step size” is 0.213 mm for an aperture of f/11 at 3x magnification using a full-frame DSLR. That’s right, 0.213 mm! The safe step size is the incremental distance at which the in-focus areas of two photos overlap. The ruler on the inexpensive focus rail that I use is marked in millimeters only, so I attempted to move the focus rail in tiny increments in two passes: one pass moving from front-to-back; and a second pass from back-to-front.

Copyright © 2018 Walter Sanford. All rights reserved.


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