The Official High-Speed Camera Thread

[Gun Freak]

Awesome! Flames in the dark always look sick!

[jackssmirkingrevenge]

[youtube][/youtube]

AGM-158 impacts, lovely.

[jrrdw]

Bunker buster!

[jackssmirkingrevenge]

Bunker buster!

Note quite as effective as the GBU-28 made out of freakin' gun barrels...

Though as usual, the Germans thought of it first...

[jrrdw]

"Though as usual, the Germans thought of it first..."

Doesn't surprise me at all. lol

[al-xg]

Love the shockwaves !

[Technician1002]

Found this HS video. I want their camera.

[youtube][/youtube]

Their other videos are good too.

[mattyzip77]

Nice find there tech! Now I wanna see them do that with a oxygen tank!!

[danielrowell]

To what degree, I wonder, does the position of the air tank and/or operation of the valve affect how evenly the force is distributed on the projectile as it exits the barrel of a pneumatic cannon? Would a coaxial cannon distribute the force more evenly because the air enters the barrel from all sides at roughly the same velocity? Would a ball valve create vortices in the barrel?

I wonder if this could be tested by adding some sort of powder to the air tank and, by filming the barrel crown with a high-speed camera, observing how the powder exits the barrel along with the projectile?

[jackssmirkingrevenge]

Their other videos are good too.

It's "only" nerf but point blank shots to the face with no eye protection is quite silly.

[jrrdw]

Benstern must have been in the neighborhood.

[Technician1002]

To what degree, I wonder, does the position of the air tank and/or operation of the valve affect how evenly the force is distributed on the projectile as it exits the barrel of a pneumatic cannon? Would a coaxial cannon distribute the force more evenly because the air enters the barrel from all sides at roughly the same velocity? Would a ball valve create vortices in the barrel?

I wonder if this could be tested by adding some sort of powder to the air tank and, by filming the barrel crown with a high-speed camera, observing how the powder exits the barrel along with the projectile?

In general, the end of the projectile is smooth, so there is very little cross wind current that can place uneven force on it. The projectile is most sensitive to the pressure on the projectile. Due to the shape of the barrel, after the projectile has moved more than a barrel diameter length, the valve has little effect on the distribution of pressure on the projectile as any pressure differences produce a rapid equalization so the pressure is relatively even. This is true for any projectile with a good barrel seal. On projectiles with lots of blow by, the area near the leak will have a localized lower pressure as the air accelerates. This low pressure is the well Bernelle principal.

In launching a barrel of dirt, flour, or other solid, the lighter gas will try to trade places with the denser solid resulting in a mixing as the gas and fine solids attempt to trade places in the barrel during heavy acceleration. The resulting in the material launches as a cloud, not a solid chunk of solids.

[Ragnarok]

Semi-related issue:

I'm looking to change my FH100's memory card - currently it's using a 4GB Class 10 Panasonic SDHC card rated at 22 MB/s.

I'd like to upgrade to a larger card (ideally 16 GB), as 4 GB doesn't last me very long and can be a problem when I'm on a trip away from a hard drive I can dump it all to.
But, at the same time, I'd like to also get a faster card to lose photos to the card quicker.

I'm looking at some of the SanDisk Extreme Cards (not the Extreme Pro, the FH100 doesn't support UHS-1), of which both the Extreme and the Extreme HD Video claim 30 MB/s.
Sounds great, but I can't actually work out why the HD Video is only classed as Class 6 (despite the same claimed data-rate) or actually what it means when it talks about "optimisation" for video.

Does anyone actually know the difference?

EDIT: Also, does anyone know what's causing the funny aberrations on my HD videos? Overexposed areas tend to go grey, except around the edges - which gives this funny haloing effect around, usually, anything framed by the sky.

EDIT EDIT: It appears to be only in the HD mode.

[al-xg]

Also, does anyone know what's causing the funny aberrations on my HD videos?

Not something I've noticed on my FH100. I've had sound cut out on replaying after 40s once, but resetting fixed that.

Are both cards 30MB/s read AND write ?

[Ragnarok]

Not something I've noticed on my FH100.

For whatever reason, it sometimes does something where all the overexposed areas are show as #848484, and I don't know why.

Are both cards 30MB/s read AND write?

That's what the SanDisk website claims. There is one place on the HD Video card page where it says "with read speeds up to 30MB/sec", but elsewhere on the page it says "up to 30MB/sec read/write speeds", so I don't know.

This wouldn't be a problem if the HD Video one wasn't the one I can find on discount... Ugh. Well, I'm sure I'll work it out.