Joseph S Wisniewski

Joseph S Wisniewski

Lives in United States Detroit, MI, United States
Works as a Speech and sensor scientist
Has a website at http://www.swissarmyfork.com
Joined on Jul 12, 2002
About me:

I've been in love with photography for over 40 years.

My favorite form of photography is macro, and much of my gear is of my own design.

I've done professional photography on and off for over 20 years.
Taught 8 years at Midwest Photography Workshops.
Designed 3 scientific digital cameras and 6 lenses.

Author of mImage and (coming soon to the App Store and Google Play) ColorForEveryone.

Comments

Total: 549, showing: 1 – 20
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In reply to:

steve_hoge: Wonder if a million lumens in 500ns at short range would serve the cops as a non-lethal "blind-gun" alternative to a stun-gun like a Taser? How would our rods and cones react to that?

Who says "we can't perceive flashes in that range of durations". I said they can't be used as a "blind gun". The human eye and the night-vision goggles both work by energy (watt-seconds) not power (watts).

These are low energy pulses, just 0.5 watt-seconds. Say you had 30 of them happening a second (that's fast enough to appear as your "continuous sequence"). That's 30 pulses/second * 0.5 watt-seconds per pulse = 15 watts. As far as either the eye or the night-vision sensor could tell, you might just as well be using a 15 watt flashlight. It would have the same effect, and be a lot cheaper.

Direct link | Posted on Dec 16, 2014 at 05:22 UTC
In reply to:

David314: Exciting to see this. I hope this comes to fruition.

This was grape, but now it is losing its a peel.

Direct link | Posted on Dec 4, 2014 at 19:00 UTC
In reply to:

David314: Exciting to see this. I hope this comes to fruition.

Edgar, now what you've has a couple of days to reflect on it, orange you berry sorry you made that "fruition" joke?

Direct link | Posted on Dec 4, 2014 at 18:18 UTC
In reply to:

steve_hoge: Wonder if a million lumens in 500ns at short range would serve the cops as a non-lethal "blind-gun" alternative to a stun-gun like a Taser? How would our rods and cones react to that?

Our photochemical response is far too slow. Millisecond and microsecond flashes are perceived by their energy, and the energy from this device is negligible, under 1 J

Direct link | Posted on Dec 4, 2014 at 18:13 UTC
In reply to:

Ilan Wittenberg: There is a similar new product called Light Cube selling currently for around $700 with the following features:
Continuous High speed flashing at full power: strobe.
Completely portable with battery internally fitted.
Over 25,000 flashes @ 1/60 of a second duration from a single battery charge at full power.
Over 150 Watts / 5,000 Lumens of light output.
Stable colour temperature. Consistent colour temp as power levels are adjusted to use as a video light: 5,600K daylight-balanced light in video mode.
Master control. Set the lighting condition of a single unit in array mode and all others will match the settings.
Modelling light feature.
Trigger remotely via sync cable, wireless trigger or as light sensitive slave.
Adjustable flash speed. Adjust the flash speed of the unit to shoot at faster or slower durations. 8000MS – 1Sec.
Seems comparable in many ways...

Except it isn't, at all.

Direct link | Posted on Dec 4, 2014 at 18:10 UTC
In reply to:

Joseph S Wisniewski: To give you an idea of what Matt has done here...

GN 5 feet with a wide angle reflector at ISO 100 takes about 0.5 watt-seconds (based on a speed light at GN 105ft at 60-80w-s, and noting that white LEDs and Xenon flash have similar luminous effacicy, 60-80l lumens/watt).

0.5w-s/(1/2,000,000)sec = 400,000 W

With 9 LEDs in series, you're talking maybe 50v at 8,000amps. Serious current to switch quickly.

So, for those saying cheap LED video lights don't cost that much, well, those are 5-20 W, not 400,000. They're not switching a power load equivalent to 4 houses full of appliances and lights on and off in under 1/1,000,000 sec.

And for those who mentioned phone LED flashes, that's 1/200 sec, not 1/2,000,000.

Are you arguing purely for the sake of arguing?

Sanyo rates the eneloops (which is just a battery I picked because I remember the mA-h rating anyway) above 1.5 A-h when discharged at 2A, which will keep a 0.5 W-s flash going at 10 flashes/second. So, it only gets about 45,000 flashes per charge if you run it that hard. Can you come up with a real-world scenario where 45,000 flashes per charge on a sub-microsecond high speed flash is a problem? Cause you'll have to tear the air gap flash apart to clean the tube 22 times in 45,000 flashes of use.

Now, as far as that air gap flash for 400 more, I take it you're talking Alan Sailer and friends. If so, you'd better reread their specs. T.1 time 2.3uS, a hell of a lot slower than the 500nS Matt is claiming for Vela.

The air gap flash had a GN of 10 feet at ISO 200, which is 7ft at ISO 100, or 1/2 stop brighter than Vela, not 2-3 stops brighter. 10 seconds to recycle with AC mains power, too.

Direct link | Posted on Dec 4, 2014 at 05:13 UTC
In reply to:

Ilan Wittenberg: There is a similar new product called Light Cube selling currently for around $700 with the following features:
Continuous High speed flashing at full power: strobe.
Completely portable with battery internally fitted.
Over 25,000 flashes @ 1/60 of a second duration from a single battery charge at full power.
Over 150 Watts / 5,000 Lumens of light output.
Stable colour temperature. Consistent colour temp as power levels are adjusted to use as a video light: 5,600K daylight-balanced light in video mode.
Master control. Set the lighting condition of a single unit in array mode and all others will match the settings.
Modelling light feature.
Trigger remotely via sync cable, wireless trigger or as light sensitive slave.
Adjustable flash speed. Adjust the flash speed of the unit to shoot at faster or slower durations. 8000MS – 1Sec.
Seems comparable in many ways...

Comparable?

The light cube's highest flash speed is 1/8,000 second.
The Vela can hit 1/2,000,000 sec.
It's 250 times faster than the Light Cube.

Direct link | Posted on Dec 4, 2014 at 04:41 UTC
In reply to:

Stanchung: Why square? For close focus wouldn't some lenses get in the way?

> For close focus wouldn't some lenses get in the way?

Do you want your lens close to a tomato being shot by a bullet? An exploding light bulb? Stack of wine glasses? A cryogenically frozen barbie doll head?

I do my high speed work with at least a 200mm micro-Nikkor, and often with that and a 1.4x TC. The wine glass pyramid was done with a 300mm and a 1.4x TC.

(I wasn't joking about barbie, btw. I've taught a high speed photography class 3 times. In each case, when I put out 20-30 objects (flowers, lenses, wine glasses, fruit, peppers, barbie) and ask "what should we blow up first", barbie wins, every time). I swear, one day I'm going to set up 3 barbie heads, trigger on the impact on the last head, and have the bullet going through a whole row of barbie.

And the toy company can't do a dang thing, because satire is protected.

Direct link | Posted on Dec 4, 2014 at 00:07 UTC
In reply to:

liquidsquid: I'm not sure if this is possible. White LEDs contain phosphors to generate the colors other than blue (of which the LEDs are based upon). The phosphors do not really turn on and off that fast. There is a charge time and a discharge time much longer than 1/2,000,000 AFAIK. If anything you will wind up with a rainbow effect on moving subjects as the various phosphors ramp up and back down in brightness as different colors will have different response times.

Sorry, that response was for a different message.

White LEDs typically use yellow YAG "Stokes fluorescence" phosphors, pumped by blue LED chips. When the "Stoke's shift" is large, like exciting an electron with blue light, and having it emit yellow light 100s of nM shorter in wavelength, the emission is fast, 10s of nS. Kill the blue, and the YAG stops emitting yellow in a few nS.

The apparent long decay is for an entirely different mechanism, very small downshifts, the YAG emitting wavelengths much closer to the exciting blue. That's why, despite the YAG being a yellow emitter while the blue chip is on, the color it decays to after a second is even cooler than the white LED, despite the blue chip being entirely off at that time. The YAG is expending a little leftover energy as blue light at a power level a fraction of a percent of its "on" power.

You're seeing the difference between the energy conversion and the phosphorescence.

Direct link | Posted on Dec 3, 2014 at 23:58 UTC
In reply to:

Joseph S Wisniewski: To give you an idea of what Matt has done here...

GN 5 feet with a wide angle reflector at ISO 100 takes about 0.5 watt-seconds (based on a speed light at GN 105ft at 60-80w-s, and noting that white LEDs and Xenon flash have similar luminous effacicy, 60-80l lumens/watt).

0.5w-s/(1/2,000,000)sec = 400,000 W

With 9 LEDs in series, you're talking maybe 50v at 8,000amps. Serious current to switch quickly.

So, for those saying cheap LED video lights don't cost that much, well, those are 5-20 W, not 400,000. They're not switching a power load equivalent to 4 houses full of appliances and lights on and off in under 1/1,000,000 sec.

And for those who mentioned phone LED flashes, that's 1/200 sec, not 1/2,000,000.

And, of course, keeping the LEDs from blowing up under that much power. The best data I have for short-pulse LEDs is that high power ones can handle about 10x their steady-state power when hit with a high power short pulse.

If the LED chips were 5 watts each, the pulse power would need to be about 50W, so you'd need thousands of LEDs to handle a 400,000W pulse. Dying to find out how Matt solved that one.

Direct link | Posted on Dec 3, 2014 at 23:40 UTC
In reply to:

Joseph S Wisniewski: To give you an idea of what Matt has done here...

GN 5 feet with a wide angle reflector at ISO 100 takes about 0.5 watt-seconds (based on a speed light at GN 105ft at 60-80w-s, and noting that white LEDs and Xenon flash have similar luminous effacicy, 60-80l lumens/watt).

0.5w-s/(1/2,000,000)sec = 400,000 W

With 9 LEDs in series, you're talking maybe 50v at 8,000amps. Serious current to switch quickly.

So, for those saying cheap LED video lights don't cost that much, well, those are 5-20 W, not 400,000. They're not switching a power load equivalent to 4 houses full of appliances and lights on and off in under 1/1,000,000 sec.

And for those who mentioned phone LED flashes, that's 1/200 sec, not 1/2,000,000.

You're confusing "energy" and "power". Matt's flash is only 0.5 watt-seconds of energy. That's a tiny amount of energy, roughly the same as what a nerf-gun dart hits you with.

The AA batteries I use, Sanyo Eneloops, hold 2.1A-h at 1.25V, which is 10.5 W-h for a set of four, or 37,800 watt-seconds. So they have enough energy for over 75,000 flashes of 0.5 watt-seconds each.

The high speed flash just delivers that small bit of energy in a very short time, requiring a very large amount of power. That's what energy is, power multiplied by time. You can cock a nerf gun in about 0.1 second, using a "massive" 5 watts of power, easy enough for even a child's hand. If it were Superman's child, it might be able to expend 400,000 watts of power and cock the gun in 1/2,000,000 second. Of course. the gun would disintegrate under that brief onslaught of enormous power.

That's the challenge Matt faced, coaxing the flash's capacitors or inductors to deliver 400,000 W for 1/2,000,000 sec.

Direct link | Posted on Dec 3, 2014 at 23:36 UTC

To give you an idea of what Matt has done here...

GN 5 feet with a wide angle reflector at ISO 100 takes about 0.5 watt-seconds (based on a speed light at GN 105ft at 60-80w-s, and noting that white LEDs and Xenon flash have similar luminous effacicy, 60-80l lumens/watt).

0.5w-s/(1/2,000,000)sec = 400,000 W

With 9 LEDs in series, you're talking maybe 50v at 8,000amps. Serious current to switch quickly.

So, for those saying cheap LED video lights don't cost that much, well, those are 5-20 W, not 400,000. They're not switching a power load equivalent to 4 houses full of appliances and lights on and off in under 1/1,000,000 sec.

And for those who mentioned phone LED flashes, that's 1/200 sec, not 1/2,000,000.

Direct link | Posted on Dec 3, 2014 at 21:52 UTC as 4th comment | 5 replies
In reply to:

five5pho: it could be revolutionary technology

I've built an Edgerton style flash, 30,000 volt caps and all. It is possible the single most dangerous thing I own. This is a lot safer. Kudos to the inventor.

Direct link | Posted on Dec 3, 2014 at 21:32 UTC
In reply to:

Paul Guba: Surprising no one is talking about the use of LED in flash unit. I find that much more interesting then the duration.

Lots of devices use LED for flash in the 1/200 sec range. This is 1//2,000,000 sec...

10,000 times faster!

There are a lot of hurdles to overcome to do that.

Direct link | Posted on Dec 3, 2014 at 21:28 UTC
In reply to:

liquidsquid: I'm not sure if this is possible. White LEDs contain phosphors to generate the colors other than blue (of which the LEDs are based upon). The phosphors do not really turn on and off that fast. There is a charge time and a discharge time much longer than 1/2,000,000 AFAIK. If anything you will wind up with a rainbow effect on moving subjects as the various phosphors ramp up and back down in brightness as different colors will have different response times.

CO2 pellet guns are fairly inexpensive, quiet, and safe, and are just the ticket for shattering wine glasses, frozen flowers (dry ice and acetone, a poor man's alternative to liquid nitrogen), light bulbs, etc.

Direct link | Posted on Dec 3, 2014 at 21:24 UTC
In reply to:

electrophoto: I for one just hope it is not like in one of those stupid horror movies where the killer keeps on popping up around every corner even after he's been killed half a dozen times...

or in other words: hopefully this will be indeed the very last of that ilk.

Hasselween
Hasselween II
Hasselween III - The Return of Larry Hansen
Hasselween H2O

Wonder what Jamie Lee Curtis is doing these days...

Direct link | Posted on Nov 26, 2014 at 01:08 UTC
In reply to:

Artistico: Just when the so-called "design" facility was closed and everyone thought it was safe to look at a Hasselblad again...

If only they'd changed the entire casing to make it appear as if it was a wooden camera, but no - they just add the grip, which doesn't really go together with the camera neither stylistically nor colour-wise, not on this planet, or on any other planet in the universe where life has reached the intelligence to make digital cameras does it go.

In fact, the intergalactical style police might just be on their way right now to arrest whoever so-called designers are behind this to deport them to the moon where, incidentally, during their lifetime incarceration, they'll be able to find some properly designed Hasselblads lying around...

You mean like this?

http://www.dpreview.com/articles/6343442605/sigmasd1wood

Direct link | Posted on Nov 26, 2014 at 00:44 UTC

Hmmm. I keep olive, walnut, padouk, and carbon fiber on hand, and am quite comfortable making grips. I could sell that grip for $100 and make a healthy profit.

And the URL PimpYoSony.com is available.

Direct link | Posted on Nov 26, 2014 at 00:36 UTC as 104th comment
In reply to:

raztec: I have a Nikon D300s and a bunch of glass. Can someone please explain why a Metz flash is any better than a Nikon? Will it work as well as a manufacturers own flash system? If I buy a Metz for my Nikon DSLR will it work with other cameras? Thx

Well, the UV content of the Metz flashes are higher than a Nikon, so fabric colors are unnatural. Wait, that's not why they're better.

The display and menu ergonomics are radically inferior to Nikon. Oops, that's not it, either.

Recycle times are worse?

The "ring form" flash isn't actually a ring light?

Never could understand how Metz lingered on as long as they did...

Direct link | Posted on Nov 25, 2014 at 02:18 UTC
In reply to:

MikeFairbanks: What's the deal with "backs" anyway? can't someone just make a medium format digital camera without having the back latch on or off? Or am I getting it wrong?

The Pentax 645D is just such a camera. In its first year, it sold more units than every other MF maker (Blad, P1, Mamiya, etc) combined.

Direct link | Posted on Nov 12, 2014 at 02:00 UTC
Total: 549, showing: 1 – 20
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