Diffusion placement for field macro with flash

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

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Dalantech
Posts: 559
Joined: Sun Aug 03, 2008 6:57 am

Post by Dalantech »

Due to the Apparent Light Size Principle the size of your diffusion surface is relative to the subject. The reason why option "A" works so well is because it's really close to what you're shooting. Me thinks the ultimate solution to your problem is going to be learning the habits and quirks of the critters that you want to photograph. For example most are more hungry that afraid early in the morning...

Image

...also early in the day, when the weather is partly cloudy, their metabolism will just tank when the sun goes behind the clouds...

Image

The more you learn about them the easier they are to photograph. Worse case you could inject a flower with sugar syrup...

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ChrisR wrote:Anvay, I'm interested to now if you can manage to get just a single catchlight if you overlap the illuminating surfaces as described? Or do your diffusers still give you hot-spots?
Actually Chis it almost works just getting them really close together:

Image

That's pretty much worse case due to the working distance. I'm considering building a single diffuser for my MT-26EX that will have the flash heads at a 45 degree angle to each other with no divider between them. Should look pretty close to a single light source.

Dalantech
Posts: 559
Joined: Sun Aug 03, 2008 6:57 am

Post by Dalantech »

anvancy wrote: The canon MT24 being one of the "to go to" flash systems for macro photography, along with other systems from olympus or even the nikon R1C1, the base remains the same. the lights sit near the lens axis.
Actually the flash heads are angled down toward the subject from above the lens. So they're not on axis. What you're describing is the light from a ring flash. Here's what the light looks like, and you can see that it's not on axis:

ImageNewborn Blue Mason Bee V by John Kimbler, on Flickr

That's with both flash heads on the Canon flash mount. Sometimes I elevate the key with a Kaiser adjustable flash shoe so that it's hitting the subject from a completely different angle from the fill. The advantage to getting the flash heads, and the diffuser, really close to the subject is that the diffusion is better and the duration of the flash is as short as possible (easier to freeze motion).

From looking at the shots of your rig, and how you use it, your flashes and diffuser are too far away from the subject.

Dalantech
Posts: 559
Joined: Sun Aug 03, 2008 6:57 am

Post by Dalantech »

Here's a shot with the key on a Kaiser adjustable flash shoe, and it's firing almost straight down. Doesn't look like it due to the angle of the specular highlight, but that's because I'm shooting from below the subject and angling the camera to make the most out of what little depth exists in a single frame.

ImageDragonfly Portrait II by John Kimbler, on Flickr

What I look for is color and texture in the specular highlight. If either is blown out then the light isn't diffused well enough. The solution is to either use a larger diffuser, get the diffuser closer to the subject, or both.

Subjects with black glossy eyes are really tough to expose for. You need the flash to turn on long enough to properly expose the scene, and at the same time compound eyes are very reflective.

ImageFinger Fed Bumblebee by John Kimbler, on Flickr

The original looks better, Flickr's jpg resizing is pretty "lossy". Although the diffusion could be better, there's still detail in the specular area.

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