Archive for the ‘Fujinon XF80mm macro lens’ Category

Which family is it?

November 29, 2022

An odonate exuvia was collected by Cindy Haddon Andrews on 03 September 2022 along the James River, near the Maidens Boat Landing in Powhatan County, Virginia USA. This specimen is from a damselfly in Suborder Zygoptera.

Pattern recognition can be used to tentatively identify damselfly larvae/exuviae to the family level: the shape of the prementum is characteristic for each of the three families found in the mid-Atlantic region of the United States of America.

Your mission, should decide to accept it, is to identify the family to which the following damselfly exuvia belongs.

03 SEP 2022 | Powhatan County, VA USA | (exuviaventral side)

The camera lens was manually focused on the prementum, located near the anterior end of the exuvia.

Here is the same photo rotated 90° clockwise.

03 SEP 2022 | Powhatan County, VA USA | (exuviaventral side)

If you think you know the family, then please leave a comment. The correct answer will be revealed in a post update.

Related Resource: How to Identify Damselfly Exuviae to Family – a photo-illustrated identification guide by Walter Sanford.

Copyright © 2022 Walter Sanford. All rights reserved.

Archilestes grandis exuvia (female)

November 25, 2022

An odonate exuvia from a Great Spreadwing damselfly (Archilestes grandis) was collected by Edgar Spalding at a small private pond in Middleton, Wisconsin USA.

SEP 2022 | Middleton, WI | Archilestes grandis (exuvia, ventral side)

External gills (3), highlighted by a blue rectangle in the following annotated image, indicate the exuvia is from a damselfly in Suborder Zygoptera.

The camera lens was manually focused on the prementum, located near the anterior end of the exuvia (highlighted by a red rectangle). The overall shape of the prementum indicates this specimen is from Family Lestidae (Spreadwings); the unique shape of the palpal lobes (highlighted by a purple rectangle) indicates Genus Archilestes.

There are two species in Genus Archilestes in North AmericaArchilestes californicus; and Archilestes grandis. I think it’s reasonable to infer this individual is A. grandis since Wisconsin is far out of range for A. californicus.

SEP 2022 | Middleton, WI | Archilestes grandis (exuvia, ventral side)

This individual is a female, as indicated by the rudimentary ovipositor located on the ventral side of its abdomen, near the posterior end (highlighted by a green rectangle in the preceding annotated image).

Related Resources

Copyright © 2022 Walter Sanford. All rights reserved.

Iberian odonate larvae

September 16, 2022

During late-October 2021, I was contacted by Miguel A. Conesa-García, PhD, Profesor Tutor Biología, Diversidad Animal, Ciencias Ambientales, UNED-Málaga.

Miguel was working on finishing the second edition of his book about odonate larvae in the Iberian Peninsula (Spain and Portugal). When Miguel was almost finished, an adult male Wandering Glider dragonfly (Pantala flavescens) was spotted in Spain. P. flavescens is a new species of odonate for the region, so Miguel decided to add the new discovery to the species list in his book.

Cover photo, courtesy Amazon Books.

The following screen capture shows the search string I used to find the book on Amazon.

Screen capture, Amazon Books.

The book is richly illustrated with beautiful photos and diagrams. It’s abundantly evident I could learn a lot from the book — I wish there were an English Edition!

Miguel requested permission to use a photo of a Wandering Glider exuvia in my photoblog, published on 14 November 2018. I was, of course, willing to help.

Page excerpt from Miguel’s book, featuring my photo.

I’m mentioned in the acknowledgements at the end of the book. Regrettably my first name is misspelled and the Web address cited is no longer current. I took the liberty of annotating the page from Miguel’s book to provide the correct information.

Acknowledgements, p. 539 (annotated).

Acknowledgements, p. 539 (original).

Migratory Dragonflies

Wandering Glider is one of at least five major species of dragonflies known to be migratory in North America. P. flavescens is the only species of odonate known to occur on every continent except Antarctica.

The exuvia that I photographed is the “cast skin” from an odonate larva (nymph) that was collected in the field by Andy Davidson, a graduate student at Virginia Commonwealth University in Richmond, Virginia USA. Andy reared the larva in the laboratory as part of a research project entitled “Predator-Prey Interactions in a Changing World.”

Part of the value in rearing odonate larvae in the laboratory is knowing with certainty that an exuvia is from a particular species. This is perhaps the reason that Miguel chose to use my photo.

Related Resources

Copyright © 2022 Walter Sanford. All rights reserved.

Fossil shark tooth, revisited

June 10, 2022

This blog post features a photo of a fossil shark tooth that I collected from the Lee Creek Phosphate Mine in Aurora, North Carolina. I didn’t record the exact date when I collected this specimen, but it was sometime between 1984 and 1989. The mine is currently open for phosphate mining, but it’s closed to the public for fossil collecting.

At the time I collected the tooth, the species of shark was called Carcharodon megalodon. Subsequently, the scientific name was changed to Carcharocles megalodon.

C. megalodon lived in “shallow” seas approximately 10 million years ago. 10 million years seems like a long time on the human time scale, but isn’t long ago on the Geologic Time Scale.

Size and jaw placement

The following annotated image shows one method for measuring the size of a fossil shark tooth. The “slant height” of the tooth is approximately four and one-quarter inches (~4 1/4″) long, as measured along the straighter edge of the tooth (lower edge, relative to the photo).

According to Gareth Williams, a member of the Megalodon Maniacs Facebook group, the tooth is from the upper jaw (lateral).

Lee Creek Phosphate Mine | C. megalodon (lingual side)

Photoblog post flashback

On 11 May 2020 I published a blog post entitled “Focus bracketing using Fujifilm X-T3” that features the same ruler shown in the preceding photo.

The 7″ plastic ruler is from the Calvert Marine Museum. Do you know why the small ruler is 7″ long rather than the more common 6″ length? Please leave a comment if you know the correct answer. Source Credit: Focus bracketing using Fujifilm X-T3.

The reason the ruler is 7″ inches long is because that’s the length of the largest fossil shark teeth ever collected — the holy grail for fossil hunters!

Tech Tips

The Adobe Photoshop “Ruler Tool” can be used to measure the number of pixels between any two points along the ruler shown in the preceding annotated image.

60s ‘shop: Using the ruler tool to measure distances in Photoshop CC, by Photoshop for the Scientist (1:00) provides a clear and concise explanation of how it’s done.

The resulting value (in pixels) can be used to set a custom scale in Photoshop in order to make other measurements of the tooth virtually.

Related Resources

Copyright © 2022 Walter Sanford. All rights reserved.

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 emerged.

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.


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