Two Sci-Fi Strobes.
While collecting information on our beloved and often frustrating underwater strobes (1), I came across two ‘back from the future’ strobes which may be of interest to Wetpixel members, one maybe for underwater use, the other to photograph a bullet as it shoots out of your favorite gun. They seem to be of interest as they may portend the kind of underwater strobes in our future.
First, here is the just released Vela Strobe, compact, elegantly designed, with four AA batteries to power it for all day use.
I quote its description (2):
“The Vela One is the fastest flash you can buy. Take pin-sharp photos of supersonic bullets and explosions using a normal SLR. The pulse width is adjustable between 500ns (1/2,000,000 sec) and 5µs (1/200,000 sec), which is fast enough to freeze a high velocity rifle bullet in flight. It can flash continuously at up to 50fps, and burst at up to 100kHz. This extremely short pulse means it needs to be orders of magnitude brighter than other LED flashes to achieve a usable exposure. The Vela One boasts nine ultra-bright 5000 lm chip-on-board LEDs, which are boosted over 2000%, giving peak flux of up to 1 million lumens.” (Please see Footnote 1)
The second strobe exists only as a two year old patent application (3) designed, maybe for deep diving submersibles, to work underwater at depths of 1,000 meters (3,281 feet) and to emit up to 30,000 lumens using a compact panel of 108 LED chips, in a hand-held light and photographic flash. The interesting idea is the use of a microprocessor to set and maintain a constant voltage to fire the LEDs (Footnote 2)..
Given the Vela’s small size, low power consumption and ultra-fast flashes, let us hope it soon re-incarnates as an all-solid state underwater photo strobe.
Notably, these two strobes of the future are built around, not flash tubes, but high lumen LED’s (4).
The Vela brochure is instructive on how to design a high performance strobe:
“THE VELA SOLUTION: A MILLION LUMENS
For pin-sharp shots you need a much faster flash, and the Vela One is 100 times faster. With a flash speed starting at 1/2,000,000 second, or 500 nanoseconds, the Vela One will stop a supersonic, high velocity rifle bullet in its tracks.
We've all seen the beautiful high speed shots of bullets passing through playing cards and apples. If you want to take these sort of photos today, you will either need a high speed camera costing tens of thousands of dollars, or a dangerous and expensive air gap flash. These use a high voltage spark to generate the short, bright flash needed. As they run at over 25,000 volts and need regular and dangerous electrode replacement, it's not surprising you can't buy them commercially. If you want one you either need to buy a vintage one for thousands of dollars, or you must build one yourself. Many super talented people have done this, but it's not an option for most of us. We wanted to solve this.
To solve the problem we turned to LEDs. Until now this has been impossible, as high speed flashes need to be extremely bright in order to get enough light onto your sensor in such a short period. We worked out we'd need to aim for up to one million lumens. If we used regular ultra-bright (500lm) LEDs we would need around 2000 to achieve this. This is obviously far too expensive and impractical. Instead we turned to the latest "chip-on-board" LEDs. These are designed for applications such as exterior lighting of large buildings. Even at ten times the brightness of the regular LEDs we'd need 200 of them, which is still far too expensive and impractical. This is where we had to get clever. After months of experimenting with different circuits and LEDs, we have built a circuit that drives nine LEDs up to 20 times brighter than rated, without damaging them or overheating, pumping out up to one million lumens. We've flashed our test units hundreds of thousands of times, and they power on through. That's years of normal use, and far longer than a speedlight will last. (2)
Footnote 2: This strobe is designed for a depth of 1,000 meters and does not seem to fulfill a real time need, but who am I to say.
1. Underwater Strobe Finder – 2019 edition. http://wetpixel.com/...showtopic=64076
2. Vela One high speed photo flash. https://shop.vela.io..._eid=072409961b
3. Feiberg, Dirk and Frey, Charles L.: High Intensity Marine LED Strobe And Torch Light. United States Patent Application 20170343185
4. Inexpensive high power, white light, 5700K COB (circuit on a board) LED’s: https://www.mouser.c...ree led&FS=True
Edited by Kraken de Mabini, 24 May 2019 - 07:15 PM.