Flash photography: 1:1 rule-of-thumb

As I was setting up for my first foray into tethered macro studio photography, I was reminded of the 1:1 rule-of-thumb that is used to determine how close/far to position a flash unit from the subject.

The diagonal distance across the face of a softbox should be the distance to the subject [or less] for soft wrap-around light. Actually, the distance should be as close as possible without the softbox showing in the photo frame. Greater distances will result in a contrasty look.

For example, my Altura softbox is a 6” x 5” rectangle (~7.8” diagonally) so it should be positioned ~8″ or less from the subject. Buyer beware: This distance is OK for macro photography but not OK for most other types of photography.

Product image courtesy altura PHOTO.

My Lastolite Ezybox Speed-Lite 2 is 8.6″ square (~12.2″ diagonally) so the softbox should be positioned approximately 12″ or less from the subject.

Product image courtesy B&H Photo.

Online Calculators

For small softboxes like the ones shown above, the diagonal distance can be measured with a 12″ (~30 cm) ruler. For larger softboxes, it might be easier to use an online calculator to determine the distance.

• Diagonal of a Rectangle Calculator
• Diagonals of a rectangle

Application

How far should should an external flash unit fitted with some type of diffuser be positioned from the backside of a translucent white plastic sheet used to create a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique?

As it turns out that’s a little more complicated to calculate, assuming you would rather not waste time with trial and error experimentation. Stay tuned for a follow-up post in which I will explain how I figured it out.

Related Resource: Flash photography: Backlighting the background.

Copyright © 2020 Walter Sanford. All rights reserved.

Leftover Cobras

At least 11 Cobra Clubtail dragonflies (Gomphurus vastus) were spotted during a photowalk with Michael Powell in Fairfax County, Virginia USA, including 10 females and one male. This blog post features photos of female No. 3 and No. 9.

No. 3

You know, some photos are better left on the cutting room floor. Like the first photo. At an aperture of f/5.6, the depth-of-field is too shallow to show both the head (soft) and tail (sharp) in focus.

Also, I think buttery soft bokeh looks better in the background than the foreground — the blurry light green grass stem in the lower-left corner would cause me to reject this photo nine times out of 10. In this case, I tried to “will” the photo to be good enough to use because I love the dew-covered vegetation.

Notice this individual’s battle-scarred wings. That’s a lot of wear and tear on a dragonfly that emerged relatively recently. She’s a survivor and you have to admire that!

08 JUN 2020 | Fairfax County, VA | Cobra Clubtail (female)

No. 9

The following photo was shot at an aperture of f/6.3 for more depth-of-field. The head looks better in this photo than the last one, but “pixel peepers” will notice it’s a little soft.

On the other hand, I like the colors and textures of the vegetation enough that this photo gets a passing grade.

08 JUN 2020 | Fairfax County, VA | Cobra Clubtail (female)

Copyright © 2020 Walter Sanford. All rights reserved.

Acceptable uncertainty

A teneral damselfly was spotted by Michael Powell during a photowalk with me along a mid-size stream in Fairfax County, Virginia USA.

teneral: adult after it has just emerged, soft and not definitively colored. Source Credit: Glossary [of] Some Dragonfly Terms, by Dennis Paulson.

Teneral odonates, especially females, can be challenging at best to identify with certainty. And so it is with this one.

The first photo is the record shot. (Get a shot, any shot.) I think I might have just missed focus on the face.

No. 1 | 15 JUL 2020 | Fairfax County, VA | teneral damselfly

Refine the shot.

No. 2 | 15 JUL 2020 | Fairfax County, VA | teneral damselfly

Although this individual is definitely a member of Family Coenagrionidae (Narrow-winged Damselflies), both the genus/species and gender are somewhat uncertain.

It appears to be an Argia sp. based on long tibial spines. I think it is a male. Source Credit: Mike Boatwright, founder and administrator of the Virginia Odonata Facebook group.

For what it’s worth, Mike Powell and I saw three species of damselflies during our outing: Blue-tipped Dancer (Argia tibialis); Dusky Dancer (Argia translata); and Powdered Dancer (Argia moesta).

I’m not sure of the gender. I see what might be hamules, indicating this individual is male, but also see what looks like a female stylus (plural: styli) near the tip of the abdomen, indicating this might be a female.

Bonus Bugs and More

Look closely at Photo No. 1, the “record shot.” Notice the small orange colored insect perched along the bottom of the same rock on which the damselfly is perched. Can anyone identify Bonus Bug No. 1?

Post Update: “The fly at the [bottom] of this photo may be a black fly (Simuliidae).” Source Credit: John Smith, member “BugGuide” Facebook group.

Now look at Photo No. 2. Notice there is some type of dark insect that’s perched along the same edge of the rock as the damselfly. Can anyone identify Bonus Bug No. 2?

Post Update: “The bug at the bottom of your photo appears to be a caddisfly.” Source Credit: John Smith, member “BugGuide” Facebook group.

Also notice the dark insect is perched near what might be the exuvia from which the damselfly emerged, as shown in Photo No. 2. It’s tannish in coloration.

I didn’t see either the bonus bugs or possible exuvia when we were in the field. Of course!

Related Resource: Newly emerged damselflies, a companion blog post by Michael Powell.

Copyright © 2020 Walter Sanford. All rights reserved.

Fishing spider Friday

I spotted a large fishing spider during a photowalk with Michael Powell along a mid-size stream in Fairfax County, Virginia USA.

15 JUL 2020 | Fairfax County, VA | fishing spider

Mike and I were searching for an uncommon species of dragonfly, but hey, we’re equal opportunity wildlife photographers who know a good subject when we see one. Please look at the full-size version of the photograph in order to appreciate its subtle color palette.

Seeing Double

Look closely at the preceding photo. Call me crazy, but I see a mean monkey face on the front half of the spider and another type of primate face on the back half. Are you with me?

Post Update

Sincere thanks to John Smith, member of the “BugGuide” Facebook group, for identifying this individual as Dolomedes scriptus, one of many species of fishing spiders.

For those of you who are struggling to see the second primate, here’s a graphic that could be helpful.

Graphic courtesy Smithsonian Channel.

Copyright © 2020 Walter Sanford. All rights reserved.

Spotlight on Slaty Skimmer

Michael Powell spotted a Slaty Skimmer dragonfly (Libellula incesta) during a photowalk with me along a mid-size stream in Fairfax County, Virginia USA.

This individual is a mature male, as indicated by his coloration, hamules, and terminal appendages.

15 JUL 2020 | Fairfax County, VA | Slaty Skimmer (male)

After a long day of searching for Eastern Least Clubtails (Stylogomphus albistylus) unsuccessfully — an uncommon species of dragonfly — it was good to see any type of dragonfly, including a common species like Slaty Skimmer!

Slaty Skimmer is a habitat generalist that can be found almost anywhere there is water.

Post Update

You know, sometimes I look at a full-frame photo and think it would look better cropped slightly. This is one of those times. So I cropped the photo and think it looks much better than the full-frame version. What do you think?

15 JUL 2020 | Fairfax County, VA | Slaty Skimmer (male)

Copyright © 2020 Walter Sanford. All rights reserved.

Cobra Clubtail dragonfly (female, No. 5)

Sometimes I think I need an editor to select my best photos. Case in point, the following photos look similar but they are subtly different.

In the first photo, the terminal appendages seem to be more in focus than in the second photo.

08 JUN 2020 | Fairfax County, VA | Cobra Clubtail (female)

The second photo shows a better view of the face while the terminal appendages are slightly softer.

08 JUN 2020 | Fairfax County, VA | Cobra Clubtail (female)

Decisions, decisions. I decided not to decide, opting to publish both photos. Which photo do you prefer?

The Backstory

At least 11 Cobra Clubtail dragonflies (Gomphurus vastus) were spotted during a photowalk with Michael Powell in Fairfax County, Virginia USA, including 10 females and one male. This blog post features two photos of female No. 5.

Copyright © 2020 Walter Sanford. All rights reserved.

Blue-tipped Dancer damselfly (male)

A Blue-tipped Dancer damselfly (Argia tibialis) was spotted during a photowalk with Michael Powell along a mid-size stream in Fairfax County, Virginia USA. Blue-tipped Dancer is a member of Family Coenagrionidae (Narrow-winged Damselflies).

This individual is a male. I love the gun metal gray color of his upper thorax stripes.

15 JUL 2020 | Fairfax County, VA | Blue-tipped Dancer (male)

Related Resource: A. tibialis male #4 (Blue-tipped Dancer)

Credit

Thanks to Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, for help in identifying this specimen.

Copyright © 2020 Walter Sanford. All rights reserved.

Odonate Calendars (updated for 2020)

Phenology (noun) is defined as “the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life.”

There is an annual cycle of odonate activity that can be subdivided into three broad categories: Early Season (spring); Mid-season (summer); and Late Season (fall).

A calendar is a good way to visualize odonate phenology. I created a new blog page called “Odonate Calendars” (see right sidebar) that features several calendars showing the adult flight period for all species of dragonflies and damselflies that can be found in the Commonwealth of Virginia.

The page includes two interactive calendars for Dr. Steve Roble’s excellent datasets for the Commonwealth of Virginia: one for dragonflies; another for damselflies. Other calendars are provided under “Related Resources.”

Copyright © 2020 Walter Sanford. All rights reserved.

Cobra Clubtail dragonfly (female, No. 6)

A Cobra Clubtail dragonfly (Gomphurus vastus) was spotted during a photowalk with Michael Powell in Fairfax County, Virginia USA.

This individual is a female, as indicated by her terminal appendages and rounded hind wings.

08 JUN 2020 | Fairfax County, VA | Cobra Clubtail (female)

The preceding photo is “full frame,” that is uncropped (3,000 x 4,000 pixels).

Copyright © 2020 Walter Sanford. All rights reserved.

Sable Clubtail dragonfly (male, No. 2)

A Sable Clubtail dragonfly (Stenogomphurus rogersi) was spotted by Michael Powell during a photowalk at a location in Fairfax County, Virginia USA. This individual is a male, as indicated by his “indented” hind wings, and terminal appendages.

Look at the blade of grass on which the Sable is perched. Notice the “leftovers” from an afternoon snack eaten by the dragonfly before the photo was taken.

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

Male dragonflies have three terminal appendages, collectively called “claspers,” that are used to grab and hold female dragonflies during mating: an upper pair of cerci (“superior appendages”); and a lower unpaired epiproct (“inferior appendage”). The epiproct for Sable Clubtail is essentially a wide plate with two prongs.

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

The spiky green grass shown below is probably shallow sedge (Carex lurida) according to Drew Chaney, a.k.a., “Plant Man Drew.”

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

Field Observations

All of the photos in the preceding gallery show male No. 2 perched on vegetation overhanging a small stream, enabling him to both hunt/feed and wait for an opportunity to mate with a female.

Natural History: Males perch on sunlit vegetation overhanging stream or on flat rocks in shade at head of riffle, fly up into trees when disturbed. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 6102-6103). Princeton University Press. Kindle Edition.

In my experience, Sable Clubtails — both male and female — also perch on ground cover vegetation in sunny clearings near small streams. For example, see my recent blog post featuring male No. 1.

Sable does in fact fly up into trees when their “flight” response is triggered by overzealous photographers; they have been observed perched in trees as high as 20 feet above the ground. Be patient — usually they return to the ground soon afterward.

Related Resources

• Sable Clubtail dragonfly (male, No. 1)
• Off-season homework pays dividends
• Field marks for identification of S. rogersi
• Stenogomphurus rogersi exuvia

Copyright © 2020 Walter Sanford. All rights reserved.