DL121 - Photec IV 20,000 FPS 16mm High Speed Film Camera Teardown

In this video i take a look at a 1980s Photec IV High Speed Motion camera that uses 16mm movie film.
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[@duncanfbrown]

Wish I'd seen this earlier! The mystery tube is a lens hood - with the prism system, lens flares from crosslight are much worse than just an annoying stray but of light. The A/E switch is for Acetate/Estar. With Estar (polyester) film you could accelerate the motor up to speed much quicker without risking shattering the film. Acetate position used a gentler acceleration profile. The mechanism is set up for .3000" between perfs on double-perf film. This was a specialty film back in the day, then became special-order only (had to buy a lot of rolls at once) and now I believe it is not offered by Kodak any more at all. (Standard double perf 16mm film is .2994" between perfs and yes that difference matters!) See my channel for some film shot with one of these, including some behind-thescenes footage of one in action.

[@mikeselectricstuff]

16mm full frame is about 0.3" high, so 400 feet = 16,000 frames. 1.6 secs at full speed! I suspect they rarely used full speed...

[@DextersTechLab]

it's a crazy speed, i need to see if it runs!

[@DoRC]

mikeselectricstuff ah. you beat me to it.

[@Techno-Universal]

Apparently they used cameras similar to that between the 1940s and 60s for filming nuclear explosive tests however the military was still massively relying on those cameras throughout their history for testing experimental weapons! Also that black tube there is most likely a film storage canister that’s missing it’s caps! :)

[@DextersTechLab]

They did indeed, both rotating prism and the faster rotating mirror (streak camera) were used in the nuclear tests.

[@Techno-Universal]

DextersTechLab Yup and those cameras were pretty much the peak of technology in the field back then however they still use rotating mirror high speed digital cameras today for following high speed moving objects like missiles and projectiles shot out of guns for example! Though of course the mirror is in front of the lens in those newer cameras and moves to change the direction of the view! :)

[@tesla500]

Those sprockets spin frighteningly fast. At 10kfps (full frame), the sprockets (and that glass prism) would spin at 10k / 8 perf = 1250 rotations per second (!), or 75,000RPM! The small guide rollers would probably break 100k RPM. I imagine chewing up the film was quite common.

[@DextersTechLab]

man, yea that is fast! Must have made quite a racket too with the motor, bearings and cogs spinning that quick

[@DoRC]

that motor is beautiful!

[@DoRC]

so at 10k fps the camera would run through the 400 ft capacity in 1.6 seconds. The film would be moving at 170mph....crazy

[@MaxKoschuh]

great video !! the hack at 18:45 is very weird. It's wire harness is more beautiful than the original ratsnest. Not done by the factory, I guess. Again, thank you very much for your support on Patreon. I would love to support you too. And I will definitely do so, once I am able to.

[@DextersTechLab]

thanks Max, we might know more about that ad-on board when i come to power it up

[@3D_Printing]

11:15 Take care at that speed the film end or a snap could rip an eye out, remember blank not real film as speed pick up slow down beginning and end

[@3D_Printing]

Odd : speed of film moving through the Gate will move faster as the film goes onto the take up spool due to diameter of the film on that spool

[@DextersTechLab]

there is the optical encoder on the prism assembly to provide feedback of the film speed, i would expect it to servo the motor as the take up reel fills up

[@whitcwa]

That's great! As I recall, they used a very long leader to let the film and prism up to speed before the unexposed film hit the gate. The fastest camera I worked on was a 400FPS, but it had a standard intermittent mechanism. Did you ever figure out what the spring noise was?

[@DextersTechLab]

no i didn't find the source of the twang noise, the bolt is just a blank, it might just been catching the edge of the motor casing

[@ah-ray]

Chris W could you tell me what camera that was?

[@whitcwa]

+Remco Ardui I believe it was a Millikan. It was chewing up the film. The claw had a buildup of plastic on the tips. All I had to do was scrape it off!

[@ah-ray]

Very cool! I subbed, btw I'm probably getting a wollensak fastax-tion because it's a lot cheaper on eBay :)

[@phreapersoonlijk]

That dev board seems like a bit of an odd addition.

[@DextersTechLab]

yes, no idea what it's doing!

[@gavincurtis]

Photonic systems? Not complete (popped) without the induction part.

[@DextersTechLab]

wonder how fast photonicinduction could make the film run

[@whitcwa]

If the motor speed was not servo controlled, the frame rate would change as the diameter of film on the takeup reel increased. They had internal and external timing light flashes for speed analysis.

[@DextersTechLab]

I didn't cover any of the motor speed control in the video but the optical encoder on the prism must provide feedback to servo the motor, maybe with PWM to that solid state relay?

[@pizzablender]

That 'out of film sensor' is probably the imprinter that can put timing marks on the film. This is also mentioned on the control panel. Still wondering how the speed would be controlled. Perhaps power it up and check the motor speed - would the motor speed vary, or is there some device braking the film?

[@BabscoSales]

Hello I have two of these do they have any value in todays digital world. Thank you

[@DextersTechLab]

Probably just a display or collectable piece today. A curiosity of the past... I had to give mine away.

[@BabscoSales]

@@DextersTechLab thank you

[@3D_Printing]

Unsure if this is any help User type manuals, etc www.dtic.mil/dtic/tr/fulltext/u2/a375524.pdf www.wikiwand.com/en/High-speed_photography