How Fast Is Your Strobe?
When talking about strobes we usually go for power, one of the first things we ask is what is the GN on the little guy, or how many WS on the big bro. That is usually the questions when you want to light more.
But what if you want to light fast? what if you are trying to freeze the action. A water drop crown or a popping balloon a good example of something slow that you want to freeze, and a bullet will be an example of something fast that you want to stop in mid air.
Strobist has a great theoretical discussion about two relevant time indicators: T0.5 and T1.0. In a nutshell, T.5 is the time it takes your flash to output half of the light, and T1.0 is the time it takes your flash to output 90% of the light.
The lower the power is, the faster the pop should be.
While Nikon strobes have this (partial) info on their specs, Canon strobes specs (at least the ones I found) lack this info all together. Wouldn't it be interesting to see how strobes measure up to those numbers in real life?
That is exactly what Maurice Ribble (from tech photo blog and cameraaxe) thought. So he made a video explaining how to measure that duration with an oscilloscope (warning, geeky equipment required) and tested a Yongnuo 460 against a Canon 580EX II and surprisingly the YN was faster. (there are some doubts raised in an interesting Strobist thread if you are engineering inclined). Video after the jump.
Measuring Flash Duration on tech photo blog
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Comments
Fast Strobes
I work in optical R&D and we recently acquired a new high speed strobe. (cost approx. $9500.00!) A full power pulse lasts 144 nanoseconds. We're using it to freeze images of droplets coming out of an inkjet nozzle in mid-flight so we can measure the drop size and calculate how many drops we need to meet our volume requirements for the application. It's just a matter of time before that gets used for something else with my camera. Any ideas for a good subject?
Hi Jim, That sounds like a
Hi Jim,
That sounds like a nice flash. Is it an air-gap flash? Those can be had for about half so either you got a more powerful or it is something more excotic than air-gap. I built an air-gap flash, but for most people xeon tube flashes are all that fit their budget or build skills.
As for subject matter, I suggest bullets. There are a few neat images at www.cameraaxe.com.
re: $9500.00 flash
Hi Jim,
I would love to know which flash is that :) seems like an amazing piece of gear.
I am going to second Maurice here and opt for bullets, or air gun if it is hard to gain access to a real gun. While you can freeze most action with "regular flashes" bullets are kinda hard to freeze. See this post and this post about how hard it is and maybe get some inspiration
Access to guns isn't a
Access to guns isn't a problem, firing them in the lab is probably not going to happen tho...
The flash is a Sugawara Laboratories Nano Pulse Light, NP-1A (with NPL-5) It's a xenon lamp, but they quench it somehow to get the short duration. Output isn't very impressive visually, but I don't know how the response time of my eyes/central nervous system compares with the flash peak output. I'll come up with some venue acceptable event to photograph.
Not to be nit-picky, but
It's called an oscilloscope, not an oscillator.
Cool video. Thanks for sharing.
Re: oscilloscope
How embarrassing, thanks for the catch :)
Well done. Very interesting
Well done. Very interesting and to the point.
Also not to be nit picky
The YN 460 as minimum power puts out a lot less light than the 580EXII on minimum power.
We're not comparing apples with apples here.
A great review though and I'd be interested to see more :)
Many of the monoblocs have a longer flash duration as the power is reduced towards minimum power. Must be a different method of cutting off flash power.
How about different powersettings?
I'd much more would like to know how they compare at full power, and how they would compare at similar light output, as they have different power in lowest setting.
More info coming
Sam, quite a few people have asked for that so I'll do a future video were I fix some of the issues with the previous video and compare light output levels. It won't be this week since I have this video done (Beginner's guide to shutter lag). Also next week's video is probably going to be about flash powder since I have an author friend wants me to do some research in that area for a book she's writing. After that I will try to get back to this.
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