Will Your Flash Last Forever?
Probably not. But seriously, how long should you expect it to last?
That totally depends on how you are using it.
First off, your flash probably doesn't have an odometer. I get my SB-800s made special—they put the odometer on the inside hinge part where I don't have to see it unless I want to.
And it might surprise you to know that 5,000 pops is an expected life span for some flash tubes. Disappointed? I was, too. And it gets worse: some tubes are rated at 1,000 pops.
I was brought into a conversation in which a flash manufacturer was trying to choose between a 5k tube and a 1k tube. My answer: spend the money on the better tube because, duh. Five thousand is better than one thousand.
But still, 5k pops sounded awfully … short-lived, amirite?
Turns out it comes down to how they test the tubes. For instance, you can expect a car to last several hundred thousand miles. But not if you drive it like a bat out of hell all the time. In that case you'll send it to a very early grave.
Same with flashes. And while there is a lot of variability in the way we use flashes, they have to test them in a consistent manner. So they test tubes in the only consistent way they can: by subjecting them to continuous, full-power pops at a rate of one every 20 seconds. It's a torture test, for lack of a better word.
So the good news is, most of us can expect our tubes to last longer. A lot longer. And even in the torture tests, they technically do. A failure is defined as "mini-cracks" starting to appear in the tubes, which lowers their output—and your resulting guide number.
Long story short, some of your speedlight flash tubes may well have already failed (technically speaking) and you might not even know it. I am not an engineer (but I am staying at a Holiday Inn Express at GPP next month, badump ping!) But most of the time in electronics the stress comes from something called thermal cycles. This is the wear and tear that comes from things repeatedly heating and cooling.
A continuous, full-power pop test would give you thermal cycles in spades, obviously. So it stands to reason that you can expect much longer lives from your flashes if you are not baking them to the max all the time.
If You Need a Truck, Buy a Truck
So this is actually really good info to know when choosing the size of light you need to do your work. If you shoot a lot of full-power outdoor speedlight portraits, you really should consider a flash that is more powerful than a speedlight.
And if you are using your light on full blast all the time, you may want to reconsider for several reasons. One, you have no headroom if you need a little more light on occasion. And two, you are probably paying for your frugality in recycle time every day. Finally, you are driving your speedlight to an early grave.
If you have to tow a big boat once a season, you can get away with using the family sedan. But if you are towing the boat every weekend, you should probably get a truck or SUV made for the job. Same with flashes.
What I've Learned
If this stuff is all new to you, fret not. It was news to me, too. Fortunately, I tend to live in the eighth- to quarter-power range. That's just where most of my speedlight portraits seem to settle out.
But when I do need to shoot at 1/1 full power, I'll be more likely to swap up to my bigger flashes going forward rather than drive the crap out of my SB-800s. Because I like my SB-800s and they don't make them any more. So I want them to be around for a long time.