Lighting the Bee

Images of undisturbed subjects in their natural environment. All subject types.

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leonardturner
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Lighting the Bee

Post by leonardturner »

_DSC2918 copyWCDen.jpg
Nikon 850, Nikon SB-700 on camera with improvised light piping and diffusion, f 16 @ 1/250th, ISO 160. Cropped and adjusted in Photoshop and Topaz Denoise.

Intrigued by some excellent field images recently posted on the site using diffused flash and numerically high f-stops combined with vigorous post-processing, I recently decided to get outside my comfort zone and have a simplistic go at it with a single flash and a diffusion system that is still evolving. This was an early result, but it raised an interesting question regarding the strongest portion of the image, which for me is found in the blurred wings.

This bee was cruising at a pretty good clip over an array of lace cap hydrangeas, pausing occasionally for a very brief time to sample their wares. The ISO was 160 with a dialed in three-quarter underexposure, so effectively 100. Sunlight was mottled, but at high noon the 1/250th-f 16 combination might be expected to underexpose by perhaps two or three stops, with main light provided by the single strobe which should provide a flash duration of around 1/1000 or somewhat faster (I can’t remember the SB-700 setting for this shot, but it was around ½ power, which Nikon says is 1/1136 second duration). It has been suggested that the bumblebee moves its four wings at some 200 beats per second, so I would expect the blurred arc of the wings to be more circumscribed than what is seen here.

My guess is that the wings were quite reflective at the angle at which they were struck by the sun and so are lit primarily by this continuous source rather than the flash, but I don’t know. I would be most interested to hear the thoughts of others—perhaps I am missing something basic.

Leonard

rjlittlefield
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Re: Lighting the Bee

Post by rjlittlefield »

Interesting image!

Thinking out loud here...

If the bumblebee is beating at 200 cycles per second, and the flash duration is 1/1000, then the flash will capture nominally 1/5 of a cycle. If the cycle is a sine wave, then 1/5 of a cycle could be almost 60% of the range of motion, assuming that it was timed to capture the center of the stroke where the sine is changing fastest.

But in the image shown here, the captured arc of the bee's right wing seems to capture the full range of motion, and the very straight and definite line above the thorax on both wings suggests that the end of the stroke was captured.

So, if you're correct about the 1/1000 second, then I don't see how the bee's right wing could have been illuminated by flash.

On the other hand, if the flash was actually on full power, say at 1/500 second with possibly a long tail, then that might work, although the brightness of the right wing's arc looks oddly uniform for that theory.

I guess I'd give a "more likely than not" to the idea of illumination by sun.

--Rik

Sym P. le
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Re: Lighting the Bee

Post by Sym P. le »

I'd suggest that the wing motion is yet more complex than Rik allows. The leading and trailing edges are not rigid as an aircraft wing, ergo the wings flap, front to back. I notice the arc tracings of points on the left wing (right side of image) are longer than the arc tracings on the right wing. I dare not go out on a limb espousing mathematical prowess lest I suffer scrapes and bruises....

Dr. Frankenstein: Yess IGOR,, good thinking....

rjlittlefield
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Re: Lighting the Bee

Post by rjlittlefield »

Sym P. le wrote:
Thu Jun 03, 2021 5:49 pm
I'd suggest that the wing motion is yet more complex than Rik allows. The leading and trailing edges are not rigid as an aircraft wing, ergo the wings flap, front to back.
I agree. It was a simple model to just get a feel for feasibility.
I notice the arc tracings of points on the left wing (right side of image) are longer than the arc tracings on the right wing.
On this, I am puzzled. The angle of view makes it hard to tell for sure, but I get that the maximum extent of the arcs appears similar on both sides. Average arc actually seems shorter on the bee's left wing, but I take that to be areas that just did not reflect. Are we looking at the same thing?

AnnotatedWings.jpg

--Rik

Sym P. le
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Re: Lighting the Bee

Post by Sym P. le »

Sorry Rik, I didn't intend to be argumentative. The total sweep is similar, I was looking more at point locations within the sweep
BeeWing.jpg

rjlittlefield
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Re: Lighting the Bee

Post by rjlittlefield »

Ah, good point!

So then, what arrangement of the wings would allow all these short arcs to be produced in the same 1/1000 flash?

It must be time to go search for slow motion video of bumblebees!

--Rik

Sym P. le
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Re: Lighting the Bee

Post by Sym P. le »

So if the flash is 1/4 the duration of the shutter, and the sunlight is adequate to light the highlights, we could expect a relatively faint overall sweep augmented by highlights over 1/4 of the sweep. I think this could explain what we are seeing.

It's interesting to see some U shaped return arcs near the inner edge of the sweep.

leonardturner
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Re: Lighting the Bee

Post by leonardturner »

Rik and Sym,

Thank you for thinking about this with me. As an fyi, the SB-700 is a bit odd in that the duration is said to be almost the same at full output, 1/1042th of a second as it is at half output, 1/1136th. At 1/4, it drops to 1/2857th and only beyond there gets seriously brief.

Any thoughts about why the right wing shows a less defined margin at the top of the arc?

I suspect there are simply too many undefined variables here to reach a really solid conclusions, but it's fun to think about.

Leonard

rjlittlefield
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Re: Lighting the Bee

Post by rjlittlefield »

Looking again at Sym P. le's markup, I notice that in the arc at the end of the green lines, for the bee's left wing, there is bright dot in the middle. So, I'm now thinking that whole arc is actually two smaller arcs that just happened to line up end-to-end, with a little bit of overlap. I've drawn a new line, in yellow, toward the bright dot.
AnnotatedWings2.jpg
Given the angle of view, that might make the left wing arcs very similar in size to the right wing arcs, and both would be easily in reach of the suggested speed of flash and wing beats.

After all this discussion, I've come around to thinking that we're seeing a conglomeration of arcs that are all or mostly due to flash. But I certainly agree that we're not going to nail it down for sure.
Any thoughts about why the right wing shows a less defined margin at the top of the arc?
Not at the moment. I had speculated something about wing deformation, but high speed videos at https://www.youtube.com/watch?v=9_hVVRw8cOA and https://www.youtube.com/watch?v=RH7BPw4pQTg suggest that the wings do not deform as much as I had expected. (The videos are fun to watch, of course.)

--Rik

Dalantech
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Re: Lighting the Bee

Post by Dalantech »

It's quite possible that the wings are exposed by the flash and under exposed by the natural light, and that would explain what you're seeing Op.

My only real .02 is to suggest setting your flash to second curtain sync so that it's the last major light source before the shutter closes -will help you to get better detail in situations where natural light is adding to the exposure.

I need to revisit this kind of shooting cause my light quality is better now -took this one 4 years ago and my light was too specular. You can see that the wings on this Digger Bee are a total blur:

ImageDigger Bee V by John Kimbler, on Flickr

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