Secret Flash Hack?

My uncle is a professional photographer. Politicians are his usual customers.

Once at some family party he took pictures with his standard looking Canon flashlight mounted to his camera.

The mystery was that he squeezed out flashes of light at an incredibly rate. (No, not red eye reduction).
Each picture had a little random exposure. Some a bit too bright, some a bit too dark. Accuracy of exposure seemed to be compromised due to a more random light generated by the flash. But that could be fixed in post production. If you need lots of flash pictures during a critical moment it would be an excellent hack.

Of course I asked him how he did it.
He was kind of quiet about it and didn't show me.

Later we talked about airport security and he said ocasionaly he gets in trouble during x-ray because one or two batteries of his flashlight are replaced by capacitors!!!
I'm thinking, that must be the hack which allows for a higher discharge rate, probably at the price of total capacity.

Does anybody know about this particular hack or has a general idea how it might work?

I asked in some photography forums and nobody got a clue. But since there are real hardware modders in here. We might solve the mystery.

Thank you.
[emoji2]

It's an interesting thought. I've been a hobby photographer for several years and use Canon. My 430EX flash with some nice eneloops has a recycle time of about a second. If he swapped out a cell or two with some capacitors that would explain the quick cycle time. My main question is that any decent flash is hard on batteries. Decreasing the available power by half would certainly limit the number of flashes you'd get.
A lot of professionals now either use a beltpack battery, or one of the adjustable LED panels for continuous light.

DrafterDan said:

It's an interesting thought. I've been a hobby photographer for several years and use Canon. My 430EX flash with some nice eneloops has a recycle time of about a second. If he swapped out a cell or two with some capacitors that would explain the quick cycle time. My main question is that any decent flash is hard on batteries. Decreasing the available power by half would certainly limit the number of flashes you'd get.
A lot of professionals now either use a beltpack battery, or one of the adjustable LED panels for continuous light.

Click to expand...

The recycle time I saw was a couple of shots per second. It felt it shot like at normal burst speed the flashes were so fast that they didn't seem to slow down the camera.
On my personal camera it also takes about a second. So very impressive what his equipment did.

He didn't have an external flash battery when I saw him but maybe during his assignments.

I don't think he shoots that much volume overall. But when he shoots then at very high frequency for a short time.

Picture a politician jumping from a landed helicopter's door to the ground. 6 pictures around that moment with super fast flash will make it likely you capture him midair.
If your flash is slower (1 per second) you'll lose the shot and then it's no help that you have more flash activations left because you have more batteries.

He picked short term frequency over overall capacity. A wedding photographer which has to take 1000th of picture per event would choose differently I guess. [emoji2]

If battery life is of minimal concern (And you have good, juicy wires) then you can make a strobe fire at almost any rate. At work we have a timing light for machinery that will flash at 600 cycles per minute. It just takes more watts...

The limit with modifying existing camera equipment is that, to put it shortly, its bits are not meant to run arbitrarily fast. I am not expert enough to guess... But I can attest that security of all kinds don't like modified electronics.

Are you sure he isn't shooting in multi-flash mode (stop action)? higher end Flashes have multi-flash mode that fire multiple times while the shutter is open My Sony's can fire up to 100x per second and stops motion like an Automotive timing light. Very cool effect and much easier with todays Digital cameras

Thank you Appleasnail
Would a capacitor simply replacing one of the batteries work? It might deliver more voltage or the same voltage but for sure faster and recycle the flash faster.
Or would one need to rewire some internals too?
What kind of capacitor could one use? I could solder one into a dummy AA.
I have a flashlight which I barely use since my new dslr is quite good in low light. So don't hesitate with any idea just so I don't melt it. I'm willing to take some risk to solve the mystery.

Thanks Vinniec5
Each flash was for a different picture. I heard the shutter shooting away and saw the pictures afterward. Some slightly over exposed and some under. Nothing to bad which couldn't be fixed in post processing/ Photoshop.
What I think this inconsistancy means is that either the lights output was varying due to the hacking of the light or the shutter and flashes were not synced 100% everytimr which would be no surprise giving the speed I witnessed.

Definitely rewired internally.

From a technical standpoint, I cannot see how replacing a battery with a capacitor would give you more strobes.

However, if you know how a flash works, the batteries charge up a capacitor, and the flash tube runs of said capacitor.
How many strobes you can get without recycle time is determined by the size of that capacitor.

I got a pro flash and I can get a few good strobes a second stock.
I imagine, he beefed up the capacitor inside his flash. Either replaced it with a bigger one, or added one, and because of the lack of internal room, he opted to cram it into the battery compartment.
The flash would probably run off 3 batteries, some models take 5 batteries, so you could loose a cell without taking a big hit to performance.
The bigger the cap, the more strobes you can get before you need to recycle. If he added a cap, it would likely be wired in parallel to the internal cap.

This gives me ideas.

As for the inconsistent exposure, that can be normal when shooting that fast and not necessarily a side effect of his mod.

A high strobe rate is limited in recharge time by the battery internal resistance. Having a capacitor charging up while the flash capacitor is charged allows a higher recharge rate. If you were constantly firing at the maximum rate your batteries can sustain it wouldn't help, but it would give you a faster repeat on the first few flashes.

A capacitor's energy density is something like "A soda-can sized super capacitor" equals one AA Eneloop. Pretty low. The power density, though...That soda can, when charged, could deliver momentary 2100A (!) and continuous 200A... for a very short time. (~0.8 Amp*hour x 2.7v gives about 4 milliseconds of discharge).

I have a guess as to how he did it. The Canon flashes have a "modeling light" mode, when you hit the test button on the flash or the picture style button on the camera (if his model has it) the flash will do a rapid burst of flashes for about a second. If he was to fire off some shots during that time I think it would get the results you mentioned. Just a thought.

I've been looking into this

http://en.wikipedia.org/wiki/Lithium-ion_capacitor

And thinking of getting a few to play around with in some lights, maybe machine out some 18650 sized Delrin holders and thread in some brass contacts to make a replacement.

This flash hack seems like a good project for these as the discharge rate would be almost as high as a capacitor and the capacity would be closer to lithium ion. Sort of a best of both worlds scenario. Also the ~30 sec charge time would be awesome, have a couple of them on a belt pack charger and swap as you get low.