I started a thread over on Scubaboard a while ago and finally realized that it would make sense to replicate it here as well.
I have been working on a scuba related personal project for a while and thought I would share some of my findings in a series of posts. My intent is to give regular updates (every few weeks?) as well as to respond to any reply posts that interest me. My intent is to present content at an introductory level where ever possible.
Bear with me. I am lazy. And maybe not very good at this...
My problem is how to happily control my scuba camera strobes.
And by Strobe I mean Flash. Don't ask me why, but scuba divers refer to an external camera flash as a strobe. Maybe you learned something today? Strobes are a very important scuba photography tool since it gets dark underwater. Very dark. Ambient light gradually reduces as you go deeper, but even worse, you lose certain colors. Things get green real quick. Strobes provide light and restore proper color balance. Google it to learn more.
Fish move. Often and quickly. Like squirrels. One technique I use underwater is continuous burst mode. I aim my camera, press the shutter and take a burst of pictures. As fast as the camera and strobe can go. Hopefully at least 1 shot will NOT feature fish butt. Depending on your camera gear, your burst speed can range anywhere from 1 frame every 5 seconds (painfully slow) to 1 frame every 2 seconds to 1 frame every second to 4 frames per second or even 20 frames per second. Burst speed depends how fast your camera AND your strobe can recycle and get ready for the next shot.
The recycle time of a strobe depends upon how much power it dumped and your battery charge level. Full dump means a longer recharge time. Low battery charge means a longer recharge cycle. Common consumer strobes are powered by 4 AA batteries (or equivalent) and generally recharge in 2 to 3 (or much longer) seconds. Partial dumps (less than full strobe power) means the strobe will ready for the next shot much sooner. Partial dumps are your friend when using continuous burst mode.
The recycle time of the camera depends upon several items. Some can be fiddled with. The camera must capture the image, process it and write it to memory card. I will ignore camera image performance. Do your own research. BUT: the onboard camera flash (yes the onboard flash is called a flash) can be an issue. If you are using optically triggered strobes (see next paragraphs), you must wait for the onboard flash to recharge before the next picture can be taken. Cameras generally have small batteries and low power onboard flashes. Without external help, this situation is not good for burst mode.
So we provide illumination help in the form of external strobes. The strobes need to be controlled by (or at least co-operate with) the camera so that the strobe discharge is synchronized with the camera shutter. Current popular technology relies upon an optical connection (fibre optic cable) to allow the strobe to act as a slave to the onboard camera flash. Old technology relied upon a physical wired sync cable connected to the camera hot shoe to fire the strobe. Optical control relies upon (and is limited by) the recycle time of the onboard flash. Sophisticated cameras realize the onboard flash is simply a trigger device (and not an illumination device) and support minimal flash power setting in order to increase the recycle speed. Non sophisticated camera don't. Wired strobes only depend upon the strobe recycle time.
So what's my problem? I bought a new camera. My new camera burst mode is worse than my old camera burst mode. Partly because my strobes optical trigger performance is poor. But the camera is also stupid.
My primary set of strobes are Sea & Sea YS110's. They support optical slave operation. But not very well. They are excellent as wired sync strobes. I used them via wired sync cables on my old camera and could achieve 4 frames per second in continuous burst mode.
I purchased a new camera in order to get better super macro performance. The hot shoe on my new camera (Canon G16) does not support continuous burst mode (more detail on this in later posts).
The G16 onboard flash does work in continuous mode, but not for long. After about 20 frames the camera pauses for 20-30 seconds. Likely a built-in flash overheat protection mechanism to allow the camera flash circuitry to cool down?
What to do...buy new strobes...fiddle with the camera...?