Another try, some better results. I did a couple of things differently. I placed the camera in a different location. I can see the surface of the water due to the reflection of the sky, and can trigger when there is activity. I looked at all my lenses and found the 35mm softest at the distances that I need. The 100mm dof is too narrow, so I shot with my A 50 1.4 at F11. I focused at 9 feet. The two remote flashes are separated by putting them on the ends of a 5 ft aluminum angle with the body in the center. The flashes are aimed to converge at 9 feet.

When there is lots of activity the Yongnuo's shut down for 5 seconds or so to recharge, which is frustrating. I had eneloops in the metz, it didn't miss a beat. The Yongnuo's had Duracell 2500mah NiMh rechargeables. I think powerpacks would help, or a second set. I think I missed shots.

Anyways, here are the best of the evening.




And the tantalizingly close one that will get me out tomorrow.


---------- Post added 08-03-14 at 11:22 PM ----------

Here is a shot from my phone of the setup.

So now you've got me thinking about this. When shooting dancers in studio with mono lights, I get one shot at the jump. You might consider trying f8, which is probably the lens sweet spot and setting flashes to 1/2 power. You'll pick up about 3 stops. Could even drop your ISO. Watch the bats with a handheld flash light so you can trip the shutter when they're coming into frame. Can they see white light? Gel with red?

You might even try full power. Even if shot every 3 or 4 seconds, that's a lot of chances.

[Class A]

I think powerpacks would help, or a second set.

More flashes would make sense, powerpacks most likely won't help.

The Yongnuos most likely take a break to cool down. Even a Godox V850 with its Li-Ion battery that will go on forever and supports very fast recycling, will slow down considerably after 20 consecutive full power shots in order to prevent the tube from being stressed too much.

The Yongnuos' batteries will also be getting very warm and may present an additional limiting factor, but the main limitation is most likely imposed by the flash tube.

[derekkite]

It may come down to shot discipline. I like the location and setup, I can see if there is a bat. At times I was able to follow one in and out of the field of view. When there are lots of them swirling about it is too tempting to hold down the button.

I think the shots were a bit better due to the choice of lens. Part of the challenge is getting them in the frame. Sometimes they are only visible when the flash illuminates them. But the location helps.

I also focused closer in, 9 feet rather than 15. I think the flash alignment was right, the Illumination is better with the units spread out. I think I will focus closer, maybe 6 or 7 feet. I capture lots of them further out but they are poorly illuminated and too small in the frame to get any detail. There have been a few to close and out of focus, which if they had been in focus would have been great shots.

Another iteration.

[delegopa]

As some already said: push your ISO up! The noise you see is not coming from a high ISO value but from quantization noise due to underexposure.
Every (Sub-)Pixel in your camera is a sensor on its own. When you continue with the current settings your these sensors are always underexposed and you get a high signal to noise ratio, meaning the noise is nearly as strong as the actual color value. On digital cameras the analog value of light gets transformed into a digital complement (quantization). From the 10 to 14 bit a camera usual has to read the full spectrum of a sensor maybe a fourth is used. The ISO values are key to keep the analog values in the operation point of this conversion. Also a weak analog signal due to low ISO is easier to disturb than a strong analog signal by exposing to the right (overexposing aside).
Just try it with those flashes you already got.

[jake14mw]

Interesting thread to see the OP's progress as he learns and becomes better. I too would raise the ISO some.

[derekkite]

Well, the concentration of bats has passed, and it will be next year or if I find another spot where it is worth shooting. I think they were congregating in a small area to take advantage of the mayfly hatches. The lake level has dropped and the hatches are less vigorous.

As for Iso, I disagree. I shoot in low light all the time as well as crop substantially. Noise means loss of detail. If I could get a filled frame with one of these critters then iso 1600 would work fine.

If all lights were flashing I got proper exposure. What improved the shots were spreading the lights out as much as possible; I had a 5 ft aluminum angle with the body and flash in the center, and one on either end. And focusing closer in got a sharper shot.

I will set myself up with a couple more flash units and a more reliable triggering mechanism for next year. The A-B-A cycling on the Cactus would work well I believe. My 35mm limited macro has something wrong with it and isn't sharp enough, the A50 1.4 was much better. A 100mm with two flashes with extenders would work as well, but it is hard to get them in the frame, possibly something a bit shorter in the 70mm range might work.