The Official High-Speed Camera Thread

[Insomniac]

Hmmm, if the ballistic gelatin is anything to go by, there can be circumstances when fruit isn't good for you!

Also, brilliant footage Insomniac, I especially liked the magnets... been a while since I kept up with this thread! Keep 'em coming

Thanks

I came up with an idea for what I think would make a VERY interesting high-speed shot, but don't have the resources to do it. Maybe somone eles has the materials required?

Basically, the idea is to find some kind of largeish light polarizing filter (think a square foot or so... perhaps there is a brand of window tint or somthing that can do it?), and a smaller, optical quality filter to put over the camera. Get a nice bright light, put a large sheet of paper in front of it so it's all evenly lit and diffused, and then put the polarizing filter in front of that. Position your camera to look directly towards it with a few meters gap, and place the polarizing filter in front of the lens, at 90 degrees to the larger one to block out as much light as possible.

Now (and here's where it gets insteresting), get a largeish sheet of some clear plastic or acrylic (somthing like a CD cover but larger), place it between the camera and the polarized light source and shoot it while filming... the stresses on the plastic will appear as shifting rainbow colours due to the way it interferes with the polarization of the light.

I'd love to see the footage but I don't have the equipment


EDIT: Wait, this looks promising... while I couldn't find polarizing sheets for anything approaching a reasonable price (or at least, an affordable price considering the projectile will probably hit it too), I found another alternative... I might buy a bunch of these single-use 3d movie glasses next time I place a dealextreme order, remove the lenses and then tile them. It won't be pretty but it ought to work, seeing as it's only being used to provide lighting... it will be out of the camera's focal range so it shouldn't look too bad.

http://www.dealextreme.com/details.dx/sku.18502



Also, while writing this I found a link to some linear polarizers with a much lower price tag (one place wanted $40 for an A4 sheet, this place wants $10)

http://www.polarizingsheet.com/linearpo ... gsheet.php

Though I'm not sure if there's a minimum order number or anything like that...

[ramses]

Sometimes I get polarizing effects without polarizing the light first.

That said, get a 40mm+ polarizing filter, duct tape it to the end of a powerful flashlight (or JSR's broken floodlight) and you have a polarized light source. I don't think you need a broad light source, the target just needs to be lit with polarizing light (from behind)

Alternatively, position it in front of an LCD monitor displaying a white image full-screen. shield accordingly.

Good Idea!

[Insomniac]

Yeah, I'll experiment with some different setups if I get my hands on some polarizing filters. The problem is that you can't use a small light source and filter to project onto say a bit of paper or somthing else like that... it won't be polarized once it bounces off. Hence why 3D cinemas have to use a 'silver screen' to maintain the polariziation. Damn it would be sooo much easier if that wasn't neccesary.

[ramses]

Don't even bother with the paper. You could buy silver paint...

I'll try my idea later today.

EDIT:

I tried plastic using my LCD monitor and a polarizing filter on the camera. I got the color fringes, but they didn't change when streass/strain was applied. I actually cracked my screwdriver case trying to get them to move...

[Insomniac]

Damn, perhaps it was the wrong type of plastic?

[ramses]

I tried a spoon and medicine cup as well. They all clearly show the color fringes, but none of the fringe move. I don't think our pitiful, non -$100k cameras could pick up the fringe changes anyway.


Now that I think of it, I remember at some science center, they had a polarized light source, polarized goggles, and what looked like drafting triangles. I believe those showed moving fringes.

I was using a circular polarizing filter, perhaps a linear filter is required...

I just tried with a clear plastic hanger, and got some minute results. Unfortunately, my trial of Vegas ran out, and the new windows movie maker sucks, so you don't get slow motion.

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[spudtyrrant]

Unfortunately, my trial of Vegas ran out, and the new windows movie maker sucks, so you don't get slow motion

*cough* torrent *cough*

[ramses]

Unfortunately, my trial of Vegas ran out, and the new windows movie maker sucks, so you don't get slow motion

*cough* torrent *cough*

I've been considering it, but we've been getting calls encouraging us to report software piracy...

After office 2007, I'm not sure I want to dig myself deeper into a hole.

We should stop talking about this, or it will get locked.

[Technician1002]

When you get those calls, remind them of the Ernie Ball story and due to their aggressive licensing enforcement, you are actively moving to a user friendly license without those legal risks. Watch them squirm. We don't deal with the Mafia and those who use their tactics of intimidation.

http://news.cnet.com/2008-1082_3-5065859.html

The Business Software Alliance (BSA) is the biggest motivation I have had to move to open source software (OSS) as much as possible and as quickly as possible. I don't pirate from torrents. I look for affordable legal alternatives.

Sorry for the off topic rant. Don't pirate software.

This is why I use The Gimp instead of Photoshop, Open Office instead of MS Office, Linux instead of Windows, etc.

In many cases the OSS solutions are better than the commercial offerings. Audacity is great for recording and editing audio. I know there are commercial offerings, but I don't bother to even know what they are.

The sea of shareware, nagware and crippleware gets left in the dust as OSS offers fully functional software built by the community to do real work besides try to pry money out of your tight budget.

I've saved enough money to keep my hardware up to date. From the P4 to Core 2 Duo, to the Core 2 Quad, and now the i5, it is money from the money saved from all the MS, Autodesk, McAffee, etc, that has helped pay for the upgrades.

[Insomniac]

Hmm, did some reading and apprently a circular polarizer ought to work. I think the problem is that the internal strains in the plastic are already so high that any extra you're adding is pretty insignificant, and drowned out by the patterns already there.

I remember when I saw this as a science exhibit (where you could flex a thick bit of plastic and easily saw the rainbow fringes indicate the strain), when you added no stress there were virtually no fringes showing. So I suppose it's just a matter of finding a bit of plastic without much internal strain in the first place.

[ramses]

yeah. I suppose one could try to stress relieve the object similar to what you would to with steels.

To the propane torch!!

But you saw the break in my video. It took around 2 frames. Granted that was at 300fps, but I don't think 1200 fps is fast enough either.

*cough* "D_Hall..." *cough*

(tech could probably do it, too.)

I use Audacity and GIMP, but windows and M$ office are too convenient for me to switch. I am also submitting to autodesk, since they have free versions for students. That way, once I graduate, I will buy their $10k software packages.

[Insomniac]

[youtube][/youtube]

Experimented a bit with a linearly polarized sunglasses lens and an LCD screen to see if I could use strain to move the polarization.

I seemed to have a better result than you got, though I suspect it's partially to do with me bending the plastic, causing the angle the plastic is at relative to the filters to change and change the patterns. Some of the colours, however, I could only achieve through applying strain to the plastic... just moving the plastic around didn't seem to change it in a similar way at all.

[ramses]

It could be the linear polarizer, too.


Bottom line: I don't think any consumer grade cameras can capture the fringes we want during an impact.

[Insomniac]

Probably not. Time to start filming some slower stuff then:

[youtube][/youtube]
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[ramses]

nice. I hope you wore ear protection for the latex tube...