Archive for the ‘Godox TT685F’ Category

Dark and moody

November 19, 2021

I spotted an emergent Uhler’s Sundragon (Helocordulia uhleri) during a photowalk along a mid-size stream at an undisclosed location in Prince William County, Virginia USA. The following photograph shows the exuvia from which the teneral adult eclosed.

13 APR 2021 | PNC. Wm. County, VA | Uhler’s Sundragon | exuvia (ventral)

In the opinion of the author, larvae (nymphs)/exuviae from Family Corduliidae (Emeralds) and Family Libellulidae (Skimmers) can be challenging to differentiate and identify to the family level.

One way to differentiate Emerald from Skimmer larvae/exuvia is to look for a “ventromedial groove” in the prementum: it’s probably Corduliidae (Emeralds) if there is a ventromedial groove; it’s probably Libellulidae if there isn’t.

Look closely at a version of the preceding photo that was reformatted, rotated, and cropped to show an enlarged view of the prementum. You should notice a ventromedial groove on the basal half of the prementum, indicating this specimen is a member of Family Corduliidae (Emeralds).

13 APR 2021 | PNC. Wm. County, VA | Uhler’s Sundragon | exuvia (ventral)

Three raised structures on the underside of the prementum remind me of the hood ornament on a 1949 Lincoln automobile. (No, I wasn’t alive in 1949!)

Related Resources

Tech Tips

One reason I underexposed the photo is to add definition to the ventromedial groove and avoid overexposing the black background.

I prefer a white background for photographing odonate exuviae. Using a black background proved to be more challenging than I expected. More later in a follow-up blog post.

Copyright © 2021 Walter Sanford. All rights reserved.

Comet Darner exuvia: annotated images

October 8, 2021

My last blog post was a “sketch pad” of test shots of an exuvia from a Comet Darner dragonfly (Anax longipes) collected by Stanley Caveney on 19 July 2021 from a pond at MeadowWoods in West Elgin, Ontario, Canada. All of the shots in that post are unedited JPGs straight from my camera. This post features edited versions of the RAF (raw) files from that photo shoot, including some images with value-added annotations.

Lateral view

I considered annotating the first photo but decided to allow it to stand on its own as the latest addition to my Odonart© Portfolio.

Comet Darner (Anax longipes) | exuvia (lateral)

Ventral view

I used Adobe Photoshop to create a composite image that features the best parts of two photos from the sketch pad.

This specimen is from a male Comet Darner, as indicated by its vestigial primary- and secondary genitalia. The inset photo shows a clear view of the vestigial hamuli (secondary genitalia) that are partially obscured in the background photo.

Comet Darner (Anax longipes) | exuvia (ventral)

Prementum

The last photo shows a closer view of the mentum, a two-segment hinged “jaw” that is used to grab food: the prementum is the segment of the labium closer to the mouth; the postmentum is the segment closer to the base of the head. Only the prementum can be seen in the following photo.

Comet Darner (Anax longipes) | exuvia (prementum)

The preceding annotated image of the prementum includes labels for the moveable hooks (2 of 2) and palpal lobe (1 of 2). Notice that A. longipes palpal lobes are squared off, in contrast with the more rounded shape of the labial palps of Common Green Darner (Anax junius).

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Comet Darner exuvia: photo sketch pad

October 5, 2021

Sometimes I shoot test shots of an odonate exuvia that are used to plan the final shots I have in mind for an identification guide featuring annotated photos.

All of the shots in this post are unedited JPGs straight from my camera, with the exception of the first ventral view (cropped to remove a distracting element from the composition).

Lateral view

I started with a lateral view of an exuvia from a Comet Darner dragonfly (Anax longipes) exuvia collected by Stanley Caveney on 19 July 2021 from a pond at MeadowWoods in West Elgin, Ontario, Canada.

Comet Darner (Anax longipes) | exuvia (lateral)

Ventral view

The next two photos show my frustratingly poor attempts to pose the specimen for shots of the ventral side of the exuvia. Every time I positioned the subject the way I wanted, it rolled over before I could take a shot!

Comet Darner (Anax longipes) | exuvia (ventral)

The two shots combined show the vestigial primary- and secondary genitalia that indicate this specimen is from a male Comet Darner. Yeah, I know it would help to annotate those parts of its anatomy, but that’s the next step. In the meantime, please follow the embedded hyperlink shown above and you might be able to figure out what I’m saying.

Comet Darner (Anax longipes) | exuvia (ventral)

Prementum

The last photo shows a closer view of the prementum. My goal was to get a better look at the labial palps. Again, annotations would help, but if you know what I’m talking about then you can see the palpal lobes are squared off.

Comet Darner (Anax longipes) | exuvia (prementum)

Copyright © 2021 Walter Sanford. All rights reserved.

Macromiidae – It’s all about the “horn.”

September 24, 2021

A “horn” on the face-head is a characteristic field mark for odonate larvae/exuviae in the Family Macromiidae (Cruisers).

Look closely at the full-size version of each of the following photos and you should be able to see the horn on the face of a Stream Cruiser dragonfly (Didymops transversa) exuvia that was collected during mid-April 2021.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (face-head)

It’s easier to see the horn in the next photo…

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

The horn is clearly visible in the last photo. Notice there are three “bumps” located between the eyes of the exuvia: the middle bump is the horn; the antennae bases are located to the left and right of the horn.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Test shots: Didymops transversa exuvia

September 21, 2021

An exuvia from a Stream Cruiser dragonfly (Didymops transversa) was collected from one of the concrete abutments of a man-made dam located along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

I prefer to photograph odonate exuvia like this one “as is” — presumably its appearance is similar to the way larva looked when it lived underwater.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

If so, then I’m guessing D. transversa larvae are bottom dwellers, as indicated by the dirty, sediment-covered dorsal side and relatively clean ventral side of this specimen.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (ventral)

Post Update

The nymphs are sprawlers that cling to roots or hunker down in sediments of mixed sand and silt particles. Source Credit: K. J. Tennessen, Dragonfly Nymphs of North America, https://doi.org/10.1007/978-3-319-97776-8_10, Macromiidae, p. 330.

The Backstory

The preceding photos were shot using the prototype for a homemade curved clear plastic tray intended for staging subjects against a white background.

With a few minor tweaks, the curved stage performed better than during initial testing. I needed to add a second external flash unit to more evenly illuminate the white background.

Although I’m fairly satisfied with the results of these test shots, more testing is required to be sure the set-up is working the way I want.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Test shots

September 17, 2021

I have been working on the prototype for a homemade curved clear plastic tray that is intended for staging subjects against a white background.

My goal for Thursday: Test the prototype stage using a toy mini-lizard as the model for some test shots, and if the proof-of-concept were established, substitute an odonate exuvia for the toy lizard and shoot another set of photos.

16 SEP 2021 | BoG Photo Studio | toy mini-lizard

Well, you know what they say about the best laid plans! First, a line of fairly strong thunderstorms moved through the region where I live so I had to shut down my computer equipment. Second, the Washington Football Team played the New York Giants on Thursday Night Football so I had to watch the game. That’s right, had to watch. Turns out it was time well-spent.

Bottom line: I never finished the test shots of the toy lizard, and of course that means I didn’t shoot any photos of a real scientific specimen.

The curved surface of the clear plastic stage caused reflections from the single external flash that was used to light the subject. I had just figured out a work-around when the thunderstorms rolled in: I took 14 test shots; only the last one (shown above) is usable. I hadn’t intended to create a photo with a pure white background, but it was easy to adjust the image exposure during post-processing.

The Backstory

What’s my motivation? Many macro photographers use insect pins for mounting small subjects like odonate exuviae. I think there’s a big problem with that technique: The position of the pin is permanent. In other words, if the pin is attached to the ventral side of the specimen then it’s challenging at best and impossible at worst to take clean, clear shots of that side of the subject. I don’t want to use insect pins because some of my specimens are one of a kind.

For quite some time, I’ve been experimenting with the use of flat clear plastic stages as a solution for this problem. I think a curved stage might be a breakthrough, but more testing is required to be sure.

For example, notice the color fringing near the tip of the lizard’s tail — I’m not sure what caused that problem in only one part of the photo, therefore I don’t know how to fix it. Yet.

To be continued. Please stay tuned.

Copyright © 2021 Walter Sanford. All rights reserved.

Anax junius versus Anax longipes

September 10, 2021

The following photograph shows the relative size of odonate exuviae from two species in the Genus Anax: junius; and longipes. Both specimens are from the Family Aeshnidae (Darners).

Relative size of exuviae from Anax junius versus Anax longipes.

The Common Green Darner dragonfly (Anax junius) exuvia was collected on 17 June 2021 from a small pond at an undisclosed location in Prince William County, Virginia USA.

The Comet Darner dragonfly (Anax longipes) exuvia was collected by Stanley Caveney on 19 July 2021 from a pond at MeadowWoods in West Elgin, Ontario, Canada.

Taxonomy

There are five species of dragonflies in the Genus Anax for the United States and Canada: Amazon Darner (Anax amazili); Common Green Darner (Anax junius); Comet Darner (Anax longipes); Giant Darner (Anax walsinghami); and Blue-spotted Comet (Anax concolor).

Common Green Darner and Comet Darner are the only species from the Genus Anax found where I live in Northern Virginia USA.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Uhler’s Sundragon dragonfly exuvia

June 1, 2021

Michael Powell spotted a small odonate exuvia clinging to the base of one of two concrete abutments for a man-made dam located along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

I collected the exuvia in order to examine it more closely in my home laboratory/photography studio. Michael photographed the specimen in my hand immediately after I removed it from the abutment, as shown in the following photo.

Photo used with written permission from Michael Powell.

The first photo shows a face-head view of the exuvia.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (exuvia)

The next two photos, showing a dorsal-lateral view of the specimen, confirm the exuvia is from a Uhler’s Sundragon dragonfly (Helocordulia uhleri).

Notice the dorsal hooks on abdominal segments seven through nine (S7-9). This distinctive character confirms the identity of the specimen as H. uhleri.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (exuvia)

Another photo taken from the same view point, exposed and edited for more contrast, shows the three dorsal hooks a little more clearly than the preceding photo.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (exuvia)

Knowing when good is good enough

A dear friend sent an article to me years ago entitled “Knowing when good is good enough.” I think she was trying to tell me something.

I tend to be a perfectionist. For example, I’m a man on a mission to take the best possible macro photographs of odonate larvae and exuviae given the limitations of my photography gear and small home studio.

Sometimes perfection is a road block that prevents me from shooting and posting photos that are more than serviceable for my purposes, in this case, informal instruction.

I did a quick Google search for the article from my friend. No luck, but I found one that’s close enough — you might even say one that’s good enough — for a little self-help.

None of the photographs in this blog post are perfect — not even close! But I published them anyway. Baby steps, Bob.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Dromogomphus spinosus exuvia (dorsal view)

February 19, 2021

Gomphidae (Clubtails) is the second largest family of dragonflies, behind Libellulidae (Skimmers). Many types of clubtail larvae (nymphs)/exuviae look similar, adding to the challenge of identifying some specimens to the genus and species level.

This specimen has a flat labium that doesn’t cover the face (not mask-like), indicating it’s either Aeshnidae (Darners) or Gomphidae; the shape of the body suggets Gomphidae. Several more field marks can be used to identify this specimen as a Black-shouldered Spinyleg (Dromogomphus spinosus) exuvia.

16 FEB 2021 | BoG Photo Studio | D. spinosus exuvia (dorsal)

The specimen is approximately 3.3 cm (~1.3 in) long, measured from head to tail. Notice the mid-dorsal hooks/spines located along the abdomen of the body.

At first I thought the exuvia might be a species from the genus Stylurus, based upon the mid-dorsal spine on abdominal segment nine (S9). After careful examination of two excellent photo-illustrated PowerPoint presentations by Kevin Hemeon at NymphFest 2016 (see Related Resources, below), I noticed none of the species in the genus Stylurus have dorsal hooks. That’s when I realized the specimen must be D. spinosus. Eureka! Source Credit: Dromogomphus spinosus exuvia – a blog post published on 28 June 2019 by Walter Sanford.

Related Resources

The following PowerPoint presentations by Kevin Hemeon are available in the “Files” section of the Northeast Odonata Facebook group. Direct links to the documents are provided below.

Odonate Exuviae – a hyperlinked list of identification guides to many species of odonate exuviae from seven families of dragonflies and three families of damselflies.

Tech Tips

The photograph featured in this blog post is a “one-off,” that is, a single photo rather than a focus-stacked composite image. The camera lens was set for f/16; the camera body was set for ISO 160 and a shutter speed of 1/250 s.

The photo was taken using a Fujifilm X-T3 digital camera, Fujifilm MCEX-11 extension tube, Fujinon XF80mm macro lens (120mm, 35mm equivalent), and an array of external lights.

Two external flash units were used to create the white background by cross lighting the front of a piece of white plastic; another flash was used to light the subject. A Sunpack LED 160 was used as a focusing aid.

RAW FILE CONVERTER EX 3.0 was used to convert one RAW (RAF) file to a TIFF file. The TIFF file was edited using Apple Aperture and sharpened using Photoshop.

Copyright © 2021 Walter Sanford. All rights reserved.

Dromogomphus spinosus exuvia (ventral view)

February 16, 2021

A dragonfly exuvia was collected by Joe Johnston on 22 May 2019 at Aquia Creek, Stafford County, Virginia USA. This specimen is the cast skin from a Black-shouldered Spinyleg (Dromogomphus spinosus) larva (nymph). D. spinosus is a member of Family Gomphidae (Clubtails).

The specimen is approximately 3.3 cm (~1.3 in) long, measured from head to tail.

15 FEB 2021 | BoG Photo Studio | D. spinosus exuvia (ventral)

Male odonates have two sets of sex organs: primary genitalia located on abdominal segment nine (S9); and secondary genitalia located on abdominal segments two-to-three (S2-3).

This male specimen has too much dirt on S9 to see the primary genitalia; the secondary genitalia are visible on S2-3. I plan to annotate the image in order to highlight select anatomical features.

Related Resources

Tech Tips

The subject was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. The exposure was increased by 0.3 stop during post-processing in order to attain a pure white background.

A composite image was created from several photos taken using a Fujifilm X-T3 digital camera, Fujifilm MCEX-11 extension tube, Fujinon XF80mm macro lens, and an array of external lights.

One external flash unit was used to create the white background and two others to light the subject. A Sunpack LED 160 was used as a focusing aid.

RAW FILE CONVERTER EX 3.0 was used to convert six (6) RAW (RAF) files to TIFF files. In a departure from my usual workflow, the TIFF files were loaded into Adobe Photoshop CC 2017 in order to create the focus stacked composite image. The composite image was edited using Apple Aperture and sharpened using Photoshop.

Tech Take-aways

Notice there is some color fringing (mostly reds) that is especially noticeable on the front legs and antennae, as well as along the edges of the posterior abdomen. I have been experimenting with a new technique for backlighting the subject. It appears I need to add another layer of diffusion between the light source and the subject.

There is also some “softness” along the edges of the abdomen that could be the result of too few focus points for the shape of the body, which in turn, could have caused artifacts in the composite image.

Copyright © 2021 Walter Sanford. All rights reserved.


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