Illumination tests on soldier fly

[Eric F]

I've been trying to decide the best way to illuminate insects (dead, pinned specimens) for macro shots with my Canon on a vertical photo stand setup. Here are three different lighting techniques using the same specimen and photo settings. The fly is a Cyphomyia sp. soldier fly (Stratiomyiidae) from Costa Rica, shot with a Canon 40D and MP-E at 2x, f/5.6, ISO 400; ZS at 0.05mm layers (no retouching in ZS, slight clean-up in PS, slightly cropped).


Lighting with B&L fiber optic guides (4 small, each with p-p diffuser), single MT-24EX flash.


Lighting with both flashes of MT-24EX, with trimmed Gary Fong diffusers.


Lighting with 144 LED ring light, indirectly reflected from plastic dome painted flat white inside.


I have results of a fourth trial, using Schott fiber optic guides (3 large, each with a p-p diffuser) and a 430EX Speedlite flash, that is not shown. Results were similar to the B&L fiber/flash setup.

The dome light is easiest to use, and gives pretty good results (except for the characteristic 'black hole effect' in the image center -- most noticeable on shiny insects like this Cyphomyia).

Eric

[elf]

I've been trying to decide the best way to illuminate insects (dead, pinned specimens) for macro shots with my Canon on a vertical photo stand setup. Here are three different lighting techniques using the same specimen and photo settings. The fly is a Cyphomyia sp. soldier fly (Stratiomyiidae) from Costa Rica, shot with a Canon 40D and MP-E at 2x, f/5.6, ISO 400; ZS at 0.05mm layers (no retouching in ZS, slight clean-up in PS, slightly cropped).


Lighting with B&L fiber optic guides (4 small, each with p-p diffuser), single MT-24EX flash.
[
Eric

What's a p-p diffuser?

Have you tried cross polarized flash or would this not work well for this type of image?

[Eric F]

Elf, sorry about the abbreviation; should have spelled-out 'ping-pong'! In these cases, just circular pieces in plastic capsules, which fit over the ends of the light guides. Doesn't work as well as a half p-p ball around the subject, with the flash heads at more of a distance; but can't always setup that arrangement.

I haven't tried cross polarized flash. I googled it, to learn more, and it seems like a good thing to try, so I ordered a small sheet from Edmund Optics. Easy to fit on the Twin Lite heads, but the MP-E lens looses the filter threads to the Twin Lite mount; still could tape something up though. Thanks for the suggestion,

Eric

[rjlittlefield]

Eric, there are several discussions of cross-polarization in the photomacrography.net forums.

One of them is HERE. If you scroll down in that topic, you'll find links to earlier discussions.

But note one little caveat at the end of the main posting:

One final question that may come to mind is this: Why not use polarized illumination with the pingpong ball, and thus become able to dial in exactly the right amount of glare to balance rich colors and visible surfaces?

The answer is, I'd love to but I haven't figured out how to pull that off yet. The trick is to either 1) polarize the fiber output and then scatter the light without changing its polarization, or 2) diffuse the light first and then polarize it before it gets to the subject. Both of these seem harder than trivial, but on the other hand, I haven't spent any time on them either. Could be there's some clever but simple approach, in which case I'd be delighted to hear about it.

If you figure out how to combine good diffusion with cross-polarization, I'd still like to hear how that goes.

--Rik

[Eric F]

Rik,

Thanks much for the very interesting & informative links. I'm constantly amazed at how much information is available in the photomacrography.net forums!

Eric

[AndrewC]

Hi Eric,

I think you might be slightly missing the point of using a ping-pong ball (p-pb) diffuser. As I understand it, you are attaching small pieces of p-pb material over the end of each fibre optic bundle. That will still you give directional illumination, though the point source is rather large. The idea of using a whole or half p-pb, and shining your light source onto the outside, is that you not only get diffuse light from your source, but you also get large amounts of secondary illumination from scatter and reflection around the inside of the p-pb.

Apologies if I'm missunderstanding your setup.

rgds,

Andrew

[Eric F]

Andrew,

You understand my setup perfectly -- thanks for the illumination! Your comments now help me to figure out why the half p-pb setup works better than just covering the tips of the light guides. I'll have to try to find larger translucent spheres to use. (I haven't found true wiffle balls -- which only have holes on 1/2 the surface -- available in local stores; they seem to have been replaced by balls entirely covered with holes -- will need to use the internet.)

Thanks, Eric

[rjlittlefield]

About the lighting, I find it helps a lot to imagine what the lights would look like from the standpoint of the subject. Bare fiber tips are small very bright spots up in the sky. Fiber tips covered by pingpong balls are a lot bigger, but they still don't cover much of the sky. Half a pingpong ball covers the whole sky, but that's not to say that it's equally bright everywhere. Depending on how close you place the tips to the ball, the bright area can vary from only a little more than the tip diameter, up to covering more than half the sky more or less evenly.

Light bouncing around inside the ball must contribute to fill lighting, but I'm not sure how much. Gut feeling, I'm inclined to think that most of the illumination comes from the first pass -- light striking the outside of the ball and passing through to get at the subject, as opposed to light reflecting off the inside of the white sphere. It would take some tricky experiments to tease those apart, though.

--Rik

[AndrewC]

... It would take some tricky experiments to tease those apart, though.

--Rik

Light source above subject, look for illumination on bottom surfaces ... obviously it also depends on how much of your diffuser actually envelops the subject, and how much of a sphere you have left, and whereabouts on the diffuser your light source hits, and the relative size of light source to diffuser to subject , and the material ...