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Overclock Your Speedlight for More Power

Editor's Note: This post was originally published on April 1st, 2008. Hint, hint.

This last weekend I got an email from M.I.T. opto-electrical engineering grad student Justin Phun, who apparently likes to tinker with commercial electronics devices for a hobby. He said he had figured out how to get into the "diagnostic mode" of the processor that controls his speedlight.

"So what," I thought.

Then he told me what he could do with his flash from the diagnostic mode. Normally this would be the point where I tell you to make the jump to read more. But before that, this:

What Justin is talking about in the rest of this post will almost certainly be outside of the warranty parameters on almost any electronic flash -- even if the manufacturer's lawyers did not have the foresight to include the actual wording. And as such, I bear absolutely no respsonsibility for whatever happens to your flash if you overclock it too far.

Now, for the good stuff, hit the jump...

FWIW, the word "overclock" normally is used to describe the process of speeding up a computer processor. But since there isn't really a word (as far as I can tell) to describe what Justin has figured out how to do, I am open to better suggestions in the comments. But for now, I'll use overclock for simplicity's sake.

What we are talking about is making your speedlight more powerful. Way more powerful.


I try to avoid the technical stuff on this site, mostly to avoid the inevitable "can you explain this to me again" emails from reader Patrick Smith. But this thing needs a little lead-in, so bear with me.

This is the main printed circuit board from inside a Nikon SB-800. And no, I did not tear mine apart for you just to get this picture. Sometimes it helps to have friends at Nikon. (Thanks, Bill!)

The chip with the circle around it is the main processor -- the NEC 40-108. As it happens, it is used in most of the strobes built by the Big Two, Nikon and Canon. The SB-800 and SB-600 is controlled by that chip, as is every Canon flash since the 430EZ.

I am not too familiar with the earlier Canon models, but I know the SB-800 and SB-600's work fine. As do the Canon 540s, 550s and 580s. (We got it to work on all of those models in Charlotte.)

Normally, these flashes all put out about 60 watt-seconds of power, give or take. But if you own one of the above flashes, you can make it go a lot higher than that.

Turbocharging Your Flash

What Justin has found is that, by a special button sequence, you can enter the flash's diagnostic mode. These special modes are normally used by technicians to test units internally while diagnosing or repairing them.

Makes sense. I had heard of that kind of thing before with computers, and actually use the diagnostic mode to better aim my XM Satellite Radio home antenna.

But if you turn on most any speedlight in it's diagnostic mode, let it charge up, turn it off, and then turn it on again, it will charge up again. And not just once, either:

For each time you re-charge the flash, you add 60 watt-seconds of power to the next time you fire it.

Apparently, the diagnostic mode fools the charging circuitry into thinking the flash has discharged. Justin thinks it has something to do with testing the charging electronics on the testing bench. Whatever.

Short answer is, you get more power.

Two charge cycles = 120 watt-seconds.
Four charge cycles = 240ws.
Eight charge cycles = 480ws -- We are talking AlienBees territory here.

So, What's the Catch?

There always a catch. In fact, this time there are two catches.

First of all, the button sequence is a bear to get timed right. Fortunately, once you get it once, you do not have to repeat it for subsequent charges on the same pop. Just turn it off and on again for each additional 60 ws.

The second catch is more important. Way more, actually...

FINAL WARNING: Don't go nuts with it. The higher you charge up your flash, the more you will stress both the flash tube and the capacitor.

We got to 300ws (five charge cycles) easily, without seeming to stress the flash at all. In fact, 300ws is the power level in the self-inflicted "test pop" John Folsom used to potentially blind illuminate himself in the photo at the top of the post.

(Exposure info: ISO 200, 1/500th of a sec, at f/32 (with the flash set at 300 watt-seconds.)

I even did several 600ws pops with no problems. And you can probably guess what happened next...

Sadly, this is what happens on a fifteen-charge-cycle pop.

Equivalent watt-seconds: Nine hundred.

I know. I'm stupid. But I couldn't help myself.

It made a loud pop, we smelled a LOT of ozone, there was a chorus of, wince-faced "oooohs" and the flash head came out looking like the pic at left. (Click it for a closer, sadder look.)

So consider that fair warning. 120 ws? Fine. 240ws? No prob. 600ws? I'd do that sparingly.

900 ws? No.

No, no, no, no, no.

And no matter what you crank your strobe up to, it is all on you. Do this at your own risk. Although, the double cycle stuff was completely harmless, FWIW.

So, I'd say 120ws is pretty darn safe. We got that much on the SB-800, the SB-600, a 540 and a 580EX (Mk II) over and over.

Finally: The Button Sequence

Okay, follow me here. Because it is harder to get than it looks in print.

But it is easy to repeat, once you get the hang of it. Shown at left is Southern Short Course student John Folsom (the first one of us to get it) as he showed the sequence to some other students.

It took me 15 minutes of trying to get it right, then I could do it almost every time. In the end, everyone in our group was able to do it:

1. The power button or switch is all you will need to use.

2. Charge the flash up and then turn it off without firing it.

3. Wait exactly one minute, then turn it back on by holding the button down for exactly five seconds. On flashes with physical switches, just switch it on.

4. Whatever you normally see in your info screen, it should be the same -- but with the word DIAG overlaid.

5. Once you get to DIAG, the rest is easy: Turn it off, then back on, for each 60ws of power you want to add.

Again, some levels: 120ws for the chickenhearted. 300ws for the playas. 600ws is pushing it.

And 900ws gets you a fried green tomato.

If You Dare to Try It, Tell Us Your Results

Whatcha gonna do with your new 300ws, pocket-sized flash? Overpower the sun? Get more aperture on your studio shots? Blind the cat? (No, not that...)

Sound off in the comments. If you exercise restraint (as opposed to me) this thing is just awesome. Just keep it to 300ws or so.

And be patient on the button sequence -- it's all about the timing. But don't get discouraged. Once we got it, repeating it was piece of cake.

I will be traveling back to Maryland today, so please be patient on the comment moderation.

POST APRIL FOOL'S DAY UPDATE: It is not like we didn't give clues -- Phonetically, the story subject and first three commenters were: Just in fun, Jokingly, April, and All in jest. And the model number of the special chip was the NEC 4 01 08.

If you believed, it was because you *wanted* to believe. Just sayin'.


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