My old, dependable optical Firefly slaves worked fine, except when I was on group trips or in show caves. Everyone else's strobes kept setting off my Firefly. I kept running down the batteries of both my Firefly and the strobe without getting many photos. There had to be a better way.
There is. Radio-controlled slaves that work with radio frequency transmitters instead of infra-red or visible light.MY CAMERA & FLASH
I switched to a small, cheap digital SLR, the entry-level Pentax K-X. It comes with a fairly good 18-55mm zoom lens (perfect for cave photography), all for about $500.
I also use Vivtar 283 strobes (which I don't recommend because the only thing holding the battery door closed is a tiny flange of plastic that breaks as soon as you step foot into a cave).
The entry-level Pentax K-X with the standard 18-55mm ZoomTHE RADIO SLAVE
Recently I purchased a Dot Line RS-RT03K/4CHS Wireless 4-Channel Flash Trigger and a couple of receivers through B&H Photography. I thoroughly tested the units during a 2-week caving trip to Australia in July - August 2010.
Dot Line RS-RT03K/4CHS Wireless 4-Channel Flash Recevier & Transmitter
The small item on the right (in the picture above) is the transmitter. It mounts to you camera's hot shoe. It measures about 1 inch to a side and is about 1/4-inch thick. It's pretty unobtrusive, but subject to getting sheared off your hot shoe in a cave nonetheless. There is a user-replaceable 12-V battery that's not something standard that you'd find at Lowe's. I am sure Radio Shack would have the batteries.
You can select one of 4 different transmitter frequencies in case there is some interference with someone else in the cave who is using radio slaves, too.
The manual says you'll get 20,000 shots from one battery, but I got more like 500 before it went dead
The transmitter doesn't have an on-off switch, but it only transmits when the camera's flash is fired. However, the little button on top is a test fire button. Stuffed away in your pack, it might be pushed into the test position all times. Maybe that's why I got only 500 shots before the battery went dead.
Advertised range is over 100 feet.
The larger item on the left (in the above photo) is the receiver that mounts to your flash. It's fairly large, about 2-1/2 inches on a side. The L-shaped bracket on the bottom is an umbrella mount that you can remove (I have no need for it). The flash attaches to one of the hot shoe mounts shown.
On the back of the receiver (not visible in this photo) are the frequency control switches and the on-off switch.
The receiver takes two AAA batteries.
HOW DID IT WORK?
The Dot Line RS-RT03K/4CHS Wireless 4-Channel Flash Trigger performed flawlessly. The charging of the strobe was the limiting factor when it came to shooting one photo after another. However, the slave's integration into the camera was another story.
With the Dot Line transmitter on the hot shoe, the camera doesn't recognize that there is a flash available. So when I tried shooting in the camera's AUTO mode, the camera took a photo at f3.5 with a shutter speed of 4 seconds because it was so dark in the cave (duh!).
So, you have to shoot in manual mode when you've got one of these babies mounted. But's that not a big deal. The exposures are all pretty similar. I set the camera to f4.5 with a shutter speed of 1/60-second and 90% of the time the exposure was correct.
$80 for one transmitter and one recevier from B&H Photo. Since the slaves comes in many different models with many different attachments, be sure you order the correct model for your specific camera and flash.
Got more than one strobe? Get only one transmitter but then get one recevier for every strobe you have.
Carry extra batteries for both the transmitter and the receivers. You'll also need a tiny Phillips head screwdriver to open the battery door in the transmitter.
Here's the link.http://www.bhphotovideo.com/c/buy/Radio-Infrared-Slaves/ci/8007/N/4289244510