January 27, 2025

Using a Canon 580EXii speedlight

I have two of these and a 550 speedlight.

For now, the game is to remember and/or figure out how to use the buttons and controls on the flash itself. Figuring out the camera interface will come later.

Startup

It needs 4 AA batteries. I use Ni-MH rechargeables. The diagram in the light refers to the end you see once you have dropped in the batteries.

Turn it on, let it charge up, and press the red "pilot" button (which should be lit up by now) to fire a test flash.

Manual Mode

The light can work in 3 modes. The "mode" button cycles between them. You get ETTL, manual, or Multi. For now we will select "manual".

Now we want a power setting. Press the "set" button in the middle of the rotating wheel. The display should blink. You can now use the wheel to select from 1/128 to 1/1.

Also of interest is the "Zoom" setting. Press the Zoom button and the display will blink. Use the wheel to select the zoom setting. You get to choose 24, 28, 35, 50, 70, 80, or 105. When you make your selection, press Zoom again and the display stops blinking. This moves something inside the flash to give you wider or narrower light. I will use 50 for now.

Cables

What you want is a male to male PC-Sync cable. Many cables are PC-Sync on one end and 3.5 mm on the other. Actually this is just what I need for my 550 speedlight. You seem to either get springy coiled cables that are too short, or crazy long (10 or 16 feet) cables with straight wire. What I want is a 2 or 3 foot cable with clean straight wire.

What I can do is buy a 3.5mm to Male flash PC cable for $6.50 on Amazon, and some of these adapters.

I have three 3.5 to 3.5 male, and three 3.5 to PC-sync cables that came with my pocket wizards.

Power cables

My 550 and 580 speedlights both have a unique 3 pin connector that would allow them to be connected to an external power source. I wonder if anyone makes an AC adapter for this? The Godox cable connects to their PB820 or PB860 power source. The PB960 is a 11.1 volt 5800 mAh battery pack.

The game is trickier than I thought. With the "key" at the top, the 3 pins are ground in the center, 300 volts on the right (!!), and a "remote on" signal that goes to the power pack on the left.

The idea here is for rapid cycling of the flash this bypasses the 6 volt to 300 volt switching circuit in the flash.

Monolights

As I consider modifying my speedlights to run off of AC, I find other people talking about this, and smarter people recommend a monolight like the "Alien Bees B400": One parameter is peak power, as shown by guide number (given as "feet" at ISO100 and for a 200mm lens) 
Godox DP400 monolight 213 to 285
Alien Bees B400 mono  118
Godox V860 speedlight 200
Canon 580 ex speed    200
Flash duration is something else. Note that most speedlights have the briefest duration at lowest power, but monolights often have the briefest duration at highest power.

Duration for the 580ex 

1/1 -- 1/250 second
1/2 -- 1/919 second
1/8 -- 1/3759 second
1/16 - 1/6024 second
1/128  1/20,000 second
An example of a Monolight is the e640 "einstein" 
1/1 -- 1/391
1/128  1/40,000

Alien Bees B400 is 1/2000 at full power, 1/1000 at 1/32 power (t.1 timings).
Rated at 160 Ws with a 150W modeling lamp and a 15 foot sync cord included $245

The Godox dp400 is 1/2000 at low power to 1/800 at high power. $219

Here is the deal on t.1 versus t.5 times. Flashes usually come on quickly then have a long tail. The t.1 time is the time to drop to 10 percent output, while the t.5 time is the time to drop to 50 percent. So the t.5 time will be shorter than the t.1 time. So the t.1 is what counts for action shooters and for considerations about fitting into camera sync times.

Now consider the Godox SK400ii-V. $169. This is a 400 Ws studio light with a 10W LED modeling light. 40 power steps from 1/16 to 1/1. Flash duration 1/2000 to 1/800, just like the dp400.

More (and ETTL)

ETTL "just works" and you can control it somewhat using flash compensation. The flash will need to be on the camera (generally a bad idea) or you will need an ETTL cable.

Feedback? Questions? Drop me a line!

Tom's Computer Info / tom@mmto.org