Canon 580 Speedlights

I have a Canon 580-EX-II speedlight, so most of what I will say here has only been verified on that particular unit.

The II designation reportedly fixes a few flaws with the original 580, including adding a metal foot in place of the plastic one on the original 580. Perhaps the best change from my point of view is that it now knows when it is on an APSC size sensor body (like the 20D) and zooms the flash appropriately.

The manual clearly states that you can use Ni-MH or Ni-Cd rechargeable batteries. This is the only sane approach to powering one of these flashes, unless you have one of the ...

External power supplies

Some good fortune placed into my hands a Dynalite "jackrabbit" unit. This is very much like the Quantum Turbo external "battery" packs. It is much more than just a battery. It is a rechargeable battery along with electronics to generate 320 volts DC which can be fed directly to the final flash circuit via the connector on the 580.

Note that when using such a pack you still need to have batteries in your 580 to power up the non-flash electronics.

Canon does not seem to specify this high voltage on any document I have ever found, and information on line makes claims from 270 volts on up to 330 volts. The Dynalite unit actually has 320 volts printed on it, and the most commonly quoted values for the Quantum unit is 325 or 330 volts. I say all this because I was concerned about blowing up my 580. Now I feel more or less at ease. The real danger with regard to blowing up a 580 flash with one of these external power sources would come from overheating the flash by agressively firing a rapid sequence of high power (or maybe not so high power) flashes without letting the 580 cool off. The 580 manual even makes some cautionary comments about this sort of thing when powered from batteries. Note that cycle times (for full power flashes) are on the order of 6 seconds using the internal batteries, and around 1.5 seconds with a Dynalite or a Quantum.

Note that a set of 4 NiMH batteries yields 4.8 volts with 2500 maH. The Quantum Turbo uses an 8 volt, 3200 maH sealed lead acid battery. The Dynalite I have has a 12 volts, 2100 maH NiCd battery. This gives these units a stored energy of 12, 25.6, and 25.2 respectively. (It is a little surprising that the external packs have only perhaps twice the stored energy, but they offer higher performance for more reasons than just a bigger battery).

Jackrabbit versus the Turbo

The Jackrabbit (now replaced by the Jackrabbit II with a NiMH battery) is lighter and smaller than the Turbo and has jacks for two flashes. To run two flashes with the Quantum Turbo, you need to either buy a Y-cable, or their new model that has two jacks. The Quantum seems to be the industry standard, but each has its pros and cons. The jackrabbit has a metal case which makes it sturdier, but some people don't like its sharp corners. One review I read said that the original Jackrabbit was known for dramatic battery explosions and such on shoots; wow! My biggest complaint about the jackrabbit is that it has no charging circuitry. It will keep charging at a constant current as long as you leave it plugged in, and this will definitely damage the battery. A 5 hour charge is the recommendation. Apparently an improved and expensive optional charger is/was available (and I would certainly recommend it). Maybe this is all fixed with the new Ni-MH based Jackrabbit-II. The new Jackrabbit II has an MSRP of $510. The optional charger is $125. They claim it will give at least 700 full power flashes.
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Adventures in Computing / [email protected]