pfrancke wrote:
Hi Floyd,
First, just to get it off my chest - I think your strategy needs to include light diffusion.
Now, having said that, running a strobe into 12 lines that can be placed as you wish is fascinating and wonderful and I can see how that would absolutely make macro shooting much more interesting. Controlling light on macro shots is always a major pain.
Could you speak more about what it takes to run a strobe into those optic cables? Also, I like very much how you control the stage area. Thank you for sharing your setup!
Hi Floyd, br br First, just to get it off my ches... (
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The picture posted is an incidental throwaway, of no significance by itself. The interesting topic is how it was made. (Incidentally I listed the magnification incorrectly, it is about 1:1.54, or a bit less than 1:1.)
The macro bench has quite an arrangement of devices to hold things like baffles, filters, reflectors, and diffusers, as well as the light guides. I didn't use any diffusers for this particular example (the purpose was avoiding the diffusion that is unavoidable in typical macro illumination setups), but diffusers are part of the basic tool kit. Lots of possibilities to explore..., mostly enabled or greatly enhanced by using the strobe light with multiple fiber guides and providing for many variations in how things can be positioned.
It isn't extremely obvious, but the camera is mounted on a StackShot motorized focusing rail. That was not used for the image shown. Higher magnification, using microscope objectives as the lens, and focus stacking is the primary purpose of the macro bench. The bench has been progressively developing for several years now.
I had the strobe and a snoot, but no experience with illumination via fiber. A week or so wandering around on eBay to see what is available, and then ordering up several light guides that looked like they might work allowed experimenting to see what did actually work.
The first thing discovered was that multiple guides was a really good thing! Larger and smaller, each provides interesting variations. The more the better too, and the limit is what can be positioned in front of a strobe's flashbulb. This bundle doesn't have any 1mm guides, but the next version will.
Positioning the fiber in the snoot didn't make much difference in light output from the guides. It's a little brighter if the fiber is closer to the flashbulb, but nothing critical. Maybe a large focusing lens would help, but the mechanics appear daunting to me. The choice of a 640 WS strobe seems good as it allows shooting at low ISO values even with the aperture stopped down to f/11.
To keep the bundle centered in the snoot I fabricated a baffle with a press fit, plus tape to hold it in place, inside the snoot. It has a hole in the center that is about the same size as the front of the snoot, and the bundle of guides extends and inch or so past the baffle toward the flashbulb. There is black foam material, both for padding and to block light, stuffed around the guides where they exit the snoot, and then it is taped up with electricians tape to hold it in place. It is not excessively sturdy, so a clamp was mounted to the shelf to support the guides.
Positioning the lights for any given subject is pretty much the same as one would do with a larger subject and many studio lights, except that the output from any given fiber guide cannot be adjusted. Multiple guides or a larger guide for more light and single smaller guides for less. Also the angle of coverage is wide enough that moving the light guide farther from the subject reduces the light intensity. Adding 1mm fiber guides to the next revision will allow illumination of very restricted areas.
This experimentation is expected to lead to developing a portable unit that can be used in the field. Not something that can be backpacked, but I'm too old for that even with lightweight gear. I want to photograph plants on the Arctic tundra, up to at least 5x magnification and hopefully with at perhaps some success at 10x. But that won't be with a 150 pound macro bench... :-)