Archive for the ‘digital videography’ Category

Thermal energy vampire!

November 24, 2017

The following photographs show an Autumn Meadowhawk dragonfly (Sympetrum vicinum) perching on Walter Sanford (hey, that’s me!) at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This individual is a male, as indicated by his terminal appendages.

All three photos were taken by Lisa Young during a photowalk with me along Easy Road.

Most dragonflies are skittish. Some species of dragonflies are “friendly,” such as Blue Corporal dragonflies (Ladona deplanata) and Autumn Meadowhawk dragonflies (Sympetrum vicinum). It’s probably not a coincidence that both types of dragonflies are early- and late-season species, when the ambient air temperature is cooler.

Some odonate experts speculate dragonflies perch on people in order to absorb thermal energy radiated by the relatively warm human body. Or in this case, a black backpack — a good spot since darker-colored objects absorb and re-radiate thermal energy more quickly than lighter-colored objects.

Related Resource: Five Guys, a blog post by Walter Sanford featuring photos of male Autumn Meadowhawk dragonflies taken before the meet-up with Liza Young.

Copyright © 2017 Walter Sanford. All rights reserved.


Blue-faced Meadowhawk (Batch 3)

October 21, 2017

This gallery features photos from Batch 3 (of 4) showing male Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum) spotted during a recent photowalk around a vernal pool at a remote location in Huntley Meadows Park, Fairfax County, Virginia USA.

Here’s looking at you, kid.

The last photograph is my favorite in this batch.

Related Resources

Copyright © 2017 Walter Sanford. All rights reserved.

Mocha Emerald terminal appendages (female)

September 29, 2017

Mocha Emerald dragonfly (Somatochlora linearis) was spotted by Andrew Rapp in Henrico County, Virginia USA. This individual is a female.

Terminal appendages

All female dragonflies have a pair of cerci (superior appendages) that have little or no function. The hind wings of female Mocha Emerald dragonflies are rounded.

21 JUL 2017 | Henrico County, VA | Mocha Emerald (female)

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

21 JUL 2017 | Henrico County, VA | Mocha Emerald (female)

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

Notice the subgenital plate shown in the preceding photo.

subgenital plate: plate below S8 that holds bunches of eggs when enlarged; variable enough in shape to be of value in identification. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 11723-11724). Princeton University Press. Kindle Edition.

“S8” refers to abdominal segment eight. Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

Oviposition (egg-laying)

The following Apple iPhone 3GS “raw” video clip shows a female Mocha Emerald dragonfly laying eggs by the process of oviposition. The process typically lasts a few seconds to a few minutes. This individual was spotted on 16 July 2011 during a photowalk through the “Wildlife Sanctuary,” one of seven small parks in the community of Hollin Hills, Fairfax County, Virginia USA.

Mocha Emerald dragonfly (female, ovipositing) [Ver. 2] (0:23)

Related Resource: Mocha Emerald terminal appendages (male).

Editor’s Note: Sincere thanks to Andrew Rapp for permission to use his still photographs.

Copyright © 2017 Walter Sanford. All rights reserved.

More focus stacking with CamRanger

April 10, 2017

When I started experimenting with completely automated focus stacking using CamRanger, I couldn’t tell what, if anything, was happening. In fact, I wasn’t sure the process was working as advertised. So I devised a plan to photograph a simple subject (a six-inch ruler in this case) and use “focus peaking” to track what happened. By the way, it’s worth noting that my Canon EOS 5D Mark II DSLR camera doesn’t feature focus peaking, but the CamRanger app does!

During initial testing, I shot several small focus stacks. The following screen capture shows the display on my iPad mini (with retina display) running the CamRanger app; the focal plane of the lens is highlighted by red focus peaking.

Here’s a screen capture from another test, showing the final location of the focal plane (highlighted in red).

I made a movie that demonstrates what happens when CamRanger creates a focus stack. It was fun to watch the focal plane advance along the ruler as CamRanger captured the shots automatically!

The movie begins with a small focus stack using a “Large” step size (the largest increment of three options). When focus stacking is active, notice that most of the screen is covered by a translucent gray layer that prevents the user from changing settings accidentally. I cancelled the focus stack after two shots. Next I changed the step size to “Medium” and started a new stack. Notice that the focal plane of the lens begins where the last focus stack ended. The new step size is noticeably smaller.

Automated focus stacking using CamRanger (2:12)

As shown in the right side bar of the CamRanger app, I set the camera to shoot RAW plus small JPG. Both file types are recorded on the memory card in the camera; thumbnail versions of the JPG files are displayed at the top of the iPad screen. Although I usually shoot RAW only, JPG files can be transferred via WiFi faster than RAW files!

I set the CamRanger app to wait 10 seconds between shots, in order to allow adequate time for the camera to write the image files to the memory card, transfer the JPG thumbnail from the camera to the app, rack the lens to the next focal plane, and for the external flash units to power cycle.

My first finished automated focus stacks

I created a 30-layer focus stack using a medium increment. The following photo shows the JPG version of the first layer.

I used Adobe Photoshop CC 2017 to create a medium-increment focus stack using the small JPGs because they can be processed faster than RAW. The resulting composite image is shown below.

Finally, here’s the resulting composite image of a five-layer focus stack created from large increment/medium JPG photos. In my opinion, the output looks almost as good as the composite image created from five times as many layers.

Lessons Learned

  • Given a choice, run the CamRanger app on the most powerful tablet you own. I use my iPad mini rather than iPad 3 (with retina display). Although the iPad 3 screen is larger than the iPad mini, it features a slower processor. That being said, the iPad 3 is perfectly suitable for using the CamRanger app for other less processor-intensive tasks.
  • Some lenses, such as my Canon EF100mm macro lens, can be set for manual focus and the CamRanger app can still rack focus automatically. It may be necessary to set other lenses for automatic focus in order to work with focus stacking in CamRanger.
  • If possible, use continuous light sources rather than external flash units. I love me some flash triggers, but they’re not 100% reliable. If you’re shooting stills and the flash fails to fire, it’s no big deal — just shoot another shot. Not so when you miss a critical focus layer. I use a combination of two small LED light sources and a Canon Speedlite tethered to the camera by a Vello flash cable; the Canon flash optically triggers a small Nissin i40 external flash (in SD mode) used for backlight.
  • Turn off “sleep mode’ for my Canon 580EX II Speedlite. (C.Fn-01 set for Disabled.)
  • It’s challenging to determine how many layers to shoot for a given focus stack, especially when using smaller step sizes. Don’t sweat it! Simply shoot more layers by starting where the focal plane is at the end of the last focus stack. Repeat as necessary until you capture as many layers as needed.

What’s next?

Going forward, my plan is to experiment with automated focus stacking using subjects that are more complex than the ruler featured in this post. Preliminary testing suggests it could be challenging to create perfect composite images of objects that are more three-dimensional than the ruler.


I used QuickTime to create the embedded movie (shown above) by tethering my iPad mini to a MacBook Air laptop computer and following the excellent directions provided in How To Display your iPad or iPhone on your Mac (9:44), a tutorial video by Terry White, Adobe Evangelist.

Related Resources

Full disclosure: There are hardware/software solutions for wireless tethering and automated focus stacking that are less expensive than CamRanger. Remember, you get what you pay for!

Copyright © 2017 Walter Sanford. All rights reserved.

Time to mate

November 13, 2016

In a recent blog post, I wrote…

Both Blue-faced Meadowhawks and Autumn Meadowhawks are classified as fall species of odonates. 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 Meadowhawks and Autumn Meadowhawks are arboreal species of dragonflies that return to the ground/water when it’s time to mateSource Credit: More previews of coming attractions.

Fall is the time to mate for Autumn Meadowhawk dragonflies (Sympetrum vicinum), as you can see in the following photo.

A mating pair of Autumn Meadowhawk dragonflies (Sympetrum vicinum) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is "in wheel."

06 NOV 2016 | HMP | Autumn Meadowhawk (mating pair, “in wheel“)

This mating pair is “in wheel.” All dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back: male dragonfly secondary genitalia, called hamules, are located in segments two and three (S2 and S3); female genitalia in segment eight (S8). Dragonflies form the mating wheel in order for their genitalia to connect during copulation.

Odonates (dragonflies and damselflies) are aquatic insects. Most of their life is spent underwater as a nymph. The life span of a nymph depends upon the species: it’s a few months for some species; a few years for other species. Individual adult odonates — like the ones we see flying around Huntley Meadows Park (HMP) — usually live one- to two months, although many different individuals from the same species may be seen for longer periods of time. Adult odonates have one goal: mate in order to reproduce. When fertilized eggs are laid in water, the circle of life comes full circle: eggs; prolarvae; larvae; emergence/adult males and females; mating pairs; males guide females to egg-laying sites (some species, such as Autumn Meadowhawk) or solo females lay eggs (all other species).

Copyright © 2016 Walter Sanford. All rights reserved.

Great Spreadwing damselflies (males, gymnasts)

November 9, 2015

The following photos show a Great Spreadwing damselfly (Archilestes grandis) spotted on 08 October 2015, two days after the first Great Spreadwing was observed at a small permanent pond in a remote location at Huntley Meadows Park (HMP). This individual is a male, nicknamed “Mr. Magoo” because of the prominent dark spots in his eyes.

A Great Spreadwing damselfly (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male, nicknamed "Mr. Magoo."

08 OCT 2015 | HMP | Great Spreadwing (male, nicknamed “Mr. Magoo”)

I’m not sure what “Mr. Magoo” was doing in the preceding photo. A novice odonate hunter might be fooled into thinking the damselfly is a female, ovipositing in the grass stem (endophytic oviposition). I speculate the young male was “test-driving” his terminal appendages, with the grass stem serving as a simulation of the neck of a female.

A Great Spreadwing damselfly (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male, nicknamed "Mr. Magoo."

08 OCT 2015 | HMP | Great Spreadwing (male, nicknamed “Mr. Magoo”)

After two seasons of field observation of Great Spreadwing damselflies, I have noticed several males flexing their abdomen like gymnasts. Are they simply stretching, or is this behavior related to a pre-/post-mating ritual? It’s impossible to know for certain, but I’m sure it’s amusing to watch! In particular, notice the unusual “two-step dance” performed by the male featured in the following video.

04 NOV 2015 | HMP | Great Spreadwing (male)

I’m a fairly accomplished photographer, he said, not too modestly. In contrast, my skills as a videographer are relatively rudimentary as evidenced by the preceding video. My movies usually turn out better when I plan the shoot and use a tripod; in this case, the video clips were shot spontaneously (therefore hand-held) when an opportunity presented itself.

One of my mantras of wildlife photography/videography is “get a shot, any shot; refine the shot.” I wish the preceding video had turned out better. Although I was able to shoot a couple of video clips of this unusual gymnastic routine, there was no opportunity to refine the shots. Oh well, maybe next year!

Related Resources:

Editor’s Note: According to Ed Lam, author and illustrator of Damselflies of the Northeast, the damselfly featured in the video is grooming itself.

He appears to be grooming in the video. They can’t reach down to knock off debris, spiderwebs, etc. but they can rub their legs together or against an object. Similarly, the abdomen seems to be contacting the wings. Sometimes you see this behavior after they have been handled and released if they don’t immediately fly away. Source Credit: Ed Lam, Northeast Odonata Facebook group.

Copyright © 2015 Walter Sanford. All rights reserved.

Slaty Skimmer dragonfly (female, laying eggs)

June 28, 2015

Slaty Skimmer (Libellula incesta) is a member of the Skimmer Family of dragonflies. Females lay eggs (oviposition) by skimming the water surface repeatedly, hence the family name “Skimmer“; two flanges beneath their eighth abdominal segment (S8) scoop water that is used to flick fertilized eggs toward shore, as illustrated in the following annotated image. Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

A Slaty Skimmer dragonfly (Libellula incesta) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature female member of a mating pair.

10 JUN 2015 | Huntley Meadows Park | Slaty Skimmer (mature female)

The preceding still photo shows a mature female Slaty Skimmer dragonfly resting immediately after copulation.

The following movie shows the same female laying eggs in a large pool of water downstream from the central wetland area at Huntley Meadows Park on 10 June 2015.

Tech Tip: The preceding movie looks better viewed in full-screen mode.

Copyright © 2015 Walter Sanford. All rights reserved.

Painted Skimmer dragonfly (female, laying eggs)

June 6, 2015

Painted Skimmer (Libellula semifasciata) is a member of the Skimmer Family of dragonflies. Females lay eggs (oviposition) by skimming the water surface repeatedly, hence the family name “Skimmer“; two flanges beneath their eighth abdominal segment (S8) scoop water that is used to flick fertilized eggs toward the shore, as illustrated in the following annotated image. Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

The following movie shows a female Painted Skimmer dragonfly laying eggs in a vernal pool at Huntley Meadows Park on 20 May 2015. (Same day, different time. Same park, different location. Same species, different female.)

Editor’s Note: Copulation between male and female Painted Skimmers occurs in-flight and is very brief, lasting just a few seconds. In my experience, oviposition is brief too. My camera was set up for shooting still photographs when I spotted the mating pair; by the time I moved into position, the pair had separated and the female was laying eggs. Fortunately I had the presence of mind to shoot video rather than stills. The video quality isn’t great, buy hey, at least I captured the moment, albeit brief!

Copyright © 2015 Walter Sanford. All rights reserved.

Painted Skimmer dragonfly (female, breathing and grooming)

June 2, 2015

The following movie features a Painted Skimmer dragonfly (Libellula semifasciata) spotted on 20 May 2015 during a photowalk alongside the wetlands at Huntley Meadows Park. This individual is a female, as indicated by its terminal appendages.

Dragonflies breathe through small holes in the underside of their thorax and abdomen called “spiracles.” Notice the dragonfly’s thorax and abdomen expanding and contracting as she inhales and exhales.

The female appears to be grooming while perching on vegetation, using her front legs to wipe her eyes and face. The author has observed many species of dragonflies engaged in similar behavior.

Tech Tips: The preceding movie looks better viewed in full-screen mode.

The video clips used to create this movie were shot on a very windy day. I used a tripod for my camera and centered the subject in each clip, but the wind caused the dragonfly to drift off-center at times. Not that I’m a perfectionist or anything.

Related Rescources:

Copyright © 2015 Walter Sanford. All rights reserved.

Green Frog (male, calling)

January 11, 2015

I spotted a Green Frog (Lithobates clamitans) along the boardwalk in the hemi-marsh at Huntley Meadows Park on 25 May 2014. This individual is a male, as indicated by the size of its tympanum (eardrum).

Females and males can be differentiated by the size of the tympanum (the eardrum, located behind the eye and below the dorsolateral ridge). In females, it is about the same size as the eye and in males it is much larger than the eye. Source Credit: Northern green frog, a Project Noah spotting by Kara Curtain/Jones, graduate student and teaching assistant at George Mason University, Department of Environmental Science and Policy.

Tech Tip: The preceding video looks better viewed in full-screen mode.

Related Resources: Some species of amphibians, such as Spring Peeper (Pseudacris crucifer), are heard more often than seen. In 2014, I resolved to learn the calls of many of the amphibians that are common at Huntley Meadows Park. The following alphabetical list provides quick links to audio recordings of several species of frogs and toads of Virginia, courtesy Virginia Herpetological Society.

Test your skill in identifying frog calls by visiting the USGS Frog Quizzes Web page. Be forewarned: The quizzes are challenging! Refer to Virginia is for Frogs for more frog-related resources including Teacher’s Corner, featuring ideas for lesson plans and activities.

Copyright © 2015 Walter Sanford. All rights reserved.

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