This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
[the following is a modified repost from Myrmecos]
A reader asks:
I also have a MP-E lens with the MT-24EX flash unit. I was curious to know something I didn’t see you mention in your recent blog post about this setup.Could you share any technical points regarding how you achieve the visible backgrounds with that lens? In general, I get very nice shots with everything beyond the focused subject completely blacked out.
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Since dark areas in photographs are the bits that aren't sending light to the camera, it follows that getting a visible backdrop means applying light behind the subject.
Earlier, I wrote that the black backdrop in macrophotography with flash is a sort of default setting. When bright flash is applied to a subject in the foreground, the background will fade to black as a matter of course. Consider this shot of acacia ants taken in a Panamanian forest:
Although I snapped this picture during the day, the photo is mostly black. That's because little ambient light penetrated the small aperture I used to gain depth-of-field. Nearly all the light comes from the flash.
To bring up the background requires increasing the ISO to pick up more ambient light (=more noise), opening the aperture (=less depth of field), decreasing the shutter speed (=more motion blur), adding a second flash aimed behind the ants (=more work), or positioning something close enough behind the subject so as to reflect some of the foreground flash. In this case, I followed the latter strategy and rigged a solution in the field:
With a colorful leaf arranged a few inches behind the ants' thorn and catching the flash, the resulting photographs have a different tone:
I was lucky that the thorny undergrowth provided an easy way to suspend a leaf. Paper clips are more reliable, and it's a good idea to carry a few in the field. In any case, the principle is the same: put something close enough behind the subject to reflect the flash.
