Posts Tagged ‘gear talk’

Post update: Cordulegastridae exuvia

February 16, 2018

In a recent blog post entitled Cordulegastridae exuvia, I was able to identify the specimen to the family level. Since then, I was able to identify the genus and species.

The dichotomous key for Cordulegastridae larvae that appears on p. 330 in Dragonflies of North America, Third Edition by Needham et al. was used to identify the exuvia.

dichotomous key: a key for the identification of organisms based on a series of choices between alternative characters. Source Credit: Merriam-Webster Dictionary.

The first couplet [1, 1′] is as follows.

1. No lateral spines on abdominal segments 8-9; western [2]
1’. Lateral spines present on segments 8-9; eastern [3]

No. 1 | Cordulegaster sp. | exuvia (ventral)

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

Since the preceding annotated image shows lateral spines on abdominal segments eight and nine (S8, S9), proceed to the third couplet [3, 3′].

3(1’). Palpal setae 4; usually 5 large and 5 small premental setae present; some setae on margin of frontal shelf spatulate (Fig. 391e) [erronea]
3’. Palpal setae 5-7; 5-9 large and 3-5 small premental setae present; all setae on frontal shelf slender, not spatulate (Fig. 391f) [4]

No. 2 | Cordulegaster sp. | exuvia (inner prementum)

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

The preceding annotated image shows the inner side of the prementum. Four (4) palpal setae are present, plus five (5) large- and five (5) small premental setae. The premental setae on the lower-right side of the prementum seem to be more intact than the ones on the upper-left: the large premental setae are labeled using white numerals; the small premental setae are labeled using red numerals.

The setae on the frontal shelf are mostly missing, as shown below. It’s possible they were broken off either when the larva burrowed in stream sediment (personal correspondence, Sue Gregoire) or when I cleaned the specimen.

No. 3 | Cordulegaster sp. | exuvia (frontal shelf)

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

Genus and species

The number of palpal setae strongly indicates the specimen is an exuvia from a Tiger Spiketail dragonfly (Cordulegaster erronea). Further, the rudimentary ovipositor shown in Photo No. 1 indicates this individual is a female.

The face behind the mask

Do you remember the way the female exuvia looked with its mask-like labium in place? In my opinion, she looked exotically beautiful!

No. 4 | Cordulegaster sp. | exuvia (face-head)

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

Well, that was then and this now. The following photo shows the face and mouth of the exuvia after the face mask was pulled away from the face in order to count the setae on the inner side of the prementum. Look closely at the full-size version of the photo. Yikes, that’s the stuff of nightmares!

No. 5 | Cordulegaster sp. | exuvia (face and mouth)

Tech Tips

The following equipment was used to shoot macro Photo No. 2, 3 and 5: Canon EOS 5D Mark II digital camera, in manual mode; Canon MP-E 65mm Macro lens (set for 2x); and Canon MT-26EX-RT Macro Twin Lite. A Sunpak LED-160 Video Light (with a white translucent plastic filter) was used for some photos.

The following equipment was used to shoot macro Photo No. 1 and 4Fujifilm X-T1 digital camera; Fujifilm MCEX-11 extension tube; and Fujinon XF80mm macro lens. An off-camera Fujifilm EF-X500 external flash unit and Sunpak LED-160 Video Light (with a white translucent plastic filter) were used for Photo No. 4. A Raynox DCR-250 close-up filter and Canon MT-26EX-RT Macro Twin Lite was used for Photo No. 1.

Adobe Photoshop CC 2017 was used to annotate selected images.

Related Resource: Cordulegastridae exuvia, a blog post by Walter Sanford featuring an exuvia collected by Mike Boatwright.

Copyright © 2018 Walter Sanford. All rights reserved.

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Tachopteryx thoreyi exuvia

February 14, 2018

A Gray Petaltail dragonfly (Tachopteryx thoreyi) exuvia was collected on 28 May 2017 by Mike Boatwright in Amherst County, Virginia USA. Gray Petaltail is a member of the Family Petaluridae (Petaltails).

The exuvia has a flat labium, similar to members of the Family Aeshnidae (Darners) and Family Gomphidae (Clubtails). Its seven-segmented antennae are thick and club-like, similar to Clubtail dragonflies.

No. 1 | Gray Petaltail (Tachopteryx thoreyi) | exuvia (face-head)

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

The specimen is ~3.5 cm long and  ~1 cm wide. The wing pads extend to the end of abdominal segment five (S5), as shown in Photo No. 2. The exuvia features two rows of dorsal hooks down its back.

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

Photo No. 3 shows a ventral view of the exuvia. Notice the “rudimentary ovipositor” located on abdominal segment nine (S9). An ovipositor is used for egg-laying by all adult damselflies and some species of adult dragonflies: females have this feature; males do not. Therefore, this individual is a female Gray Petaltail.

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

Tech Tips

The following equipment was used to shoot all of the preceding photographs: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tube; Canon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite. A Sunpak LED-160 Video Light (with a white translucent plastic filter) was used for some photos.

Adobe Photoshop CC 2017 was used to annotate selected images.

The Backstory

Mike Boatwright has steadfastly resisted my best efforts to lure him to the dark side of odonate exuviae collection and identification. As a concession to me, Mike kindly agreed to look-out for exuviae in unusual habitats. As it turns out, the first exuvia Mike collected for me is a prized specimen. Perhaps I should have titled this post “Mike strikes gold in Virginia!”

Image used with permission from Mike Boatwright.

“Beginner’s luck?” Nope. I know from firsthand experience Mike Boatwright is an extraordinarily keen-eyed odonate hunter. Way to go, Mike!

Related Resource

The dichotomous key for Petaluridae larvae that appears on p. 320 in Dragonflies of North America, Third Edition by Needham et al. is as follows.

1. Antennae 6-segmented, 3rd and 5th segments longer than wide (Fig. 381); cerci each more than 1/2 as long as epiproct; lateral margins of abdominal segments 3-9 not expanded, lateral spines inconspicuous; western [Tanypteryx (p. 322)]
1’. Antennae 7-segmented, 3rd and 5th segments not longer than wide (Fig. 379); cerci each less than 1/2 as long as epiproct; lateral margins of abdominal segments 3-9 expanded, lateral spines conspicuous; eastern [Tachopteryx (p. 321)]

Copyright © 2018 Walter Sanford. All rights reserved.

How to calculate magnification

February 12, 2018

By definition, a true macro photo is one with a magnification of at least 1/1, that is, one unit in the real world is equal to at least one of the same units on the camera sensor. Magnification can be calculated using the following formula.

actual size of image / size of camera sensor = magnification

Both measurements must be expressed in the same units in order for the units to cancel during division.

For example, let’s look at the following “full-size” image of a Corduligastridae exuvia. “Full-size” means the image is uncropped (4896 x 3264 pixels).

The photograph shown above was taken using a Fujifilm X-T1 digital camera, Fujifilm MCEX-11 extension tube, and Fujinon XF80mm macro lens. The specifications for the macro lens lists the maximum magnification as 1x. Question is, how much is the magnification increased by adding the 11 mm extension tube?

The dragonfly exuvia is approximately 35 mm in length (3451 pixels). The following proportion can be used to solve for the length of the entire image, in millimeters (mm).

x mm / 35 mm = 4896 pixels / 3451 pixels

x = 49.65 mm, or ~50 mm. In other words, if a metric ruler were placed in the scene then 50mm of the ruler would be shown in the preceding photograph.

The X-T1 features an APS-C sensor (23.6 mm x 15.6 mm). Calculate the magnification using the following formula.

50 mm / 23.6 mm = 2.11x or ~2.0x

The subject is actually ~2.0x larger than life size on the camera sensor.

1.19x is listed as the theoretical maximum magnification using an MCEX-11 extension tube mounted on the 80mm macro lens. If we round the spec’d magnification to ~1.2x, then it’s clear that the actual magnification of ~2.0x is slightly greater than advertised.

Related Resource: Photomacrography using Bellows and Extensions (13:11), by Gale Spring, Adjunct Associate Professor of Scientific Photography at RMIT University in Melbourne, Australia.

Copyright © 2018 Walter Sanford. All rights reserved.

Different point of view

January 15, 2018

The first photo shows “The Osprey’s at Belmont Bay,” as seen from the opposite side of Belmont Bay. “The Osprey’s” community shares a common boundary with Occoquan Bay National Wildlife Refuge, located to the left of this photo.

11 JAN 2018 | Prince William County, VA | The Osprey’s at Belmont Bay

The next photo shows the near shoreline of Belmont Bay. The bay is almost completely covered by ice after two weeks of below-freezing temperatures.

11 JAN 2018 | Fairfax County, VA | Belmont Bay

Notice the duck blind located in the water.

11 JAN 2018 | Fairfax County, VA | Belmont Bay

The following photo shows a dock and boat ramp located at the mouth of a small stream that is a tributary of Belmont Bay.

11 JAN 2018 | Fairfax County, VA | dock and boat ramp

The next photo is located upstream from the dock and boat ramp.

11 JAN 2018 | Fairfax County, VA | small tributary of Belmont Bay

The last photo shows a location far upstream from Belmont Bay. The stream is located at the bottom of a steep-sided valley.

11 JAN 2018 | Fairfax County, VA | small tributary of Belmont Bay

Tech Tip: I used my Panasonic Lumix DMC-FZ150 superzoom camera to shoot the landscape 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.”

Copyright © 2018 Walter Sanford. All rights reserved.

Resting on a Coleman camp stool

January 13, 2018

In addition to my photography gear, I usually carry a Coleman camp stool when I go photowalking. The small, lightweight folding chair is good for resting while waiting for “the game to come to me.” The camp stool also enables me to get closer to subjects either on- or near the ground. And I think it’s easier to hold my camera rock-steady when I’m sitting on the chair with my elbows resting on my knees.

I like my Coleman camp stool. Some of my favorite insects like to rest on the camp stool too!

22 OCT 2017 | HMP | Autumn Meadowhawk (male, perching on a stool)

An Autumn Meadowhawk dragonfly (Sympetrum vicinum) was spotted near a vernal pool at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male, perching on a Coleman camp stool.

22 OCT 2017 | HMP | Autumn Meadowhawk (male, perching on a stool)

22 OCT 2017 | HMP | Autumn Meadowhawk (male, perching on a stool)

Copyright © 2018 Walter Sanford. All rights reserved.

Have you ever wondered…?

January 9, 2018

Have you ever wondered…

The preceding photo shows the “focal plane mark” on my Fujifilm X-T1 digital camera.

The same mark appears on my Canon EOS 5D Mark II DSLR, as shown on p. 16 of the “Instruction Manual.”

Minimum focusing distance versus working distance

The “minimum focusing distance” is the distance from the subject to the focal plane. The “working distance” is the distance from the front of the lens to the subject.

For example, the minimum focusing distance for the Fujinon XF80mm macro lens (shown above) is 246 mm (24.6 cm). The working distance is 98 mm (9.8 cm).

Magnification (or magnification ratio)

True macro lenses have a magnification ratio of at least 1:1, meaning the size of the subject is the same size on the focal plane (digital sensor).

For example, the digital sensor for the Fujifilm X-T1 is 23.6 mm wide by 15.6 mm high. At a magnification ratio of 1:1, a subject that is 15 mm (1.5 cm) long will be 15 mm (1.5 cm) wide on the digital sensor; expressed another way, the subject will fill ~64% of the frame width.

For a prime macro lens, maximum magnification of 1:1 is possible only at the minimum focusing distance; magnification is necessarily lower at longer focusing distances.

Adding an extension tube

Adding a Fujifilm MCEX-11 extension tube reduces the working distance to 89 mm (8.9 cm). It’s interesting to note the minimum focusing distance of 249 mm (24.9 cm) is essentially the same, with or without the extension tube.

The net effect of adding an extension tube is the magnification ratio is increased to a value greater than 1:1, say 1.2:1, so the subject appears slightly larger on the focal plane.

Related Resource: Adding an 11mm extension tube, a blog post by Walter Sanford.

Copyright © 2018 Walter Sanford. All rights reserved.

More light diffusion

January 7, 2018

A toy dinosaur was photographed using a Canon MT-26EX-RT Macro Twin Lite mounted on a Canon EF 100mm f/2.8L Macro IS lens (set for manual focus), Kenko 20mm macro automatic extension tube, and Canon EOS 5D Mark II DSLR camera (set for manual exposure). Snap-on plastic light diffusers were mounted on both flash heads.

The first photo shows a wider view of the small plastic toy.

Default light diffusion on both flash heads (snap-on plastic diffusers).

The next photo shows a closer view of the same toy. Specular highlights are more noticeable when the flash heads are closer to the subject.

Default light diffusion on both flash heads (snap-on plastic diffusers).

More light diffusion was added by mounting four layers of translucent white plastic foam on the right flash head (facing forward). Notice the specular highlights are less glaring on the right side of the last photo than on the left.

More light diffusion added to right flash head (facing forward).

Copyright © 2018 Walter Sanford. All rights reserved.

Toys are for testing

January 5, 2018

The first photo shows a laid-back toy monkey, photographed using a Canon MT-26EX-RT Macro Twin Lite mounted on a Fujinon XF80mm macro lensFujifilm MCEX-11 extension tube, and Fujifilm X-T1 digital camera.

The Fujinon macro lens is tack sharp. Hotspots from the Canon macro twin lite, technically known as specular highlights, are visible in two regions of the monkey’s face. Although snap-on plastic light diffusers were used with both flash units, additional diffusion seems to be necessary.

The last two photos were taken using the same external macro flash unit mounted on a Canon MP-E 65mm Macro lens (set for 1x) and a Canon EOS 5D Mark II DSLR.

The preceding photo shows a rubber duck, SWAG from the Sleep Inn in Staunton, Virginia.

The following photo shows Totodile, a Pokemon character. Depth of field is noticeably very shallow. The focus point is the eye of the toy.

Copyright © 2018 Walter Sanford. All rights reserved.

Macro flash for Fujinon 80mm macro lens

December 22, 2017

The following photograph shows a Canon MT-26EX-RT Macro Twin Lite mounted on a Fujinon XF80mm macro lensFujifilm MCEX-11 extension tube, and Fujifilm X-T1 digital camera.

Two adapter rings are used for mounting the macro flash unit on the macro lens: a Sensei PRO 62-67mm step-up ring (upper-left); and Canon Macrolite Adapter 67C (lower-right).

The filter size for the Fujinon 80mm macro lens is 62mm. A 62-67mm step-up ring is used to connect the macro lens with the Canon Macrolite Adapter 67C, so named because it works with “most 67mm filter size lenses.” In this case, it works perfectly with the Fujinon 80mm macro lens.

Like every other Canon external flash that I own, the new macro flash is compatible with my Fuijifilm X-T1 digital camera. TTL is incompatible, so it’s manual mode flash only with the X-T1. That’s not a problem since I prefer manual exposure for macro photography. Although high-speed sync is supported by the Canon MT-26EX-RT Macro Twin Lite, it’s incompatible with the Fujifilm X-T1.

Related Resources

The filter size for the Fujinon XF55-200mm lens is 62mm. Therefore the same combination of adapter rings described above can be used to mount the Canon macro flash on the 55-200mm lens. The lens, in combination with one or more extension tubes, can be used for macro photography. The most magnification results at 200mm; the least magnification at 55mm.

The Canon Macrolite Adapter 58C can be used to mount the Canon macro flash on the Fujinon XF18-55mm “kit” lens (58mm filter size). The Macrolite Adapter 58C cannot be seen in the following photo, but it’s there. This lens, in combination with one or more extension tubes, can be used for macro photography although in my experience the 55-200mm lens is a better choice for that purpose.

Canon MT-26EX-RT adapter mounted on Fujinon XF 18-55mm lens.

The front of the Canon MT-26EX-RT adapter has a filter size of 58mm. The next photo shows a Raynox DCR-250 close-up filter mounted on the MT-26EX-RT adapter using two adapter rings: a Sensei 58-52mm step-down ring; and a Sensei 52-43mm step-down ring. The same combination of adapter rings can be used to mount the Raynox close-up filter on any lens to which the MT-26EX-RT adapter is mounted.

Raynox DCR-250 close-up filter and Canon MT-26EX-RT adapter.

Most of the time I carry the Raynox close-up filter connected to the Sensei 52-43mm step-down ring because it fits a couple of lenses that I own with a 52mm filter size, such as the fixed lens on the Panasonic Lumix DMC-FZ150 superzoom camera (my go-to camera kit for photowalking).

MT-24EX versus MT-26EX-RT

The Canon MT-26EX-RT Macro Twin Lite is the successor to the Canon Macro Twin Lite MT-24EX. The MT-24EX supports E-TTL with Canon DSLRs; it doesn’t support high-speed sync. The MT-24EX is $160 less expensive than the newer MT-26EX-RT (MSRP $829.99 versus $989.99). Both models are compatible with the Canon Macrolite Adapter 67C and Canon Macrolite Adapter 58C.

As the owner a Canon DSLR, I could rationalize the higher cost for the newer model because I like to shoot Shutter Priority using shutter speeds faster than the default sync speed of my camera. If you need a macro flash for Fujifilm digital cameras only, then you may want to consider buying the less expensive model.

Copyright © 2017 Walter Sanford. All rights reserved.

Light-modifier

December 20, 2017

Here’s a light-modifier for external flash units like the Fujifilm EF-X500, shown below. It’s simple, and works surprisingly well.

Simple light-modifier mounted on a Fujifilm EF-X500 external flash.

Mount a translucent white plastic foam bag on the flash head, secure it using a rubber band, and voila! In this case, I repurposed a foam bag that came with my Raynox DCR-250 close-up filter.

Thanks to Alan Pezzulich for sharing the idea for this clever light-modifier with me during a walk-and-talk about some of his techniques for field macro photography.

Copyright © 2017 Walter Sanford. All rights reserved.


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