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effect of G-forces?


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#1 Felipe Perez-Burchard

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Posted 21 March 2009 - 02:31 PM

Hello all,

I'm working on a TV show, we are shooting on F35s.
Upcoming is a scene that involves putting the cameras on a roller coaster and we are all a bit worried about what the effects of the g-forces created by the high travelling speeds might be on the tape based format (HDCAM-SR) and on the camera itself.

The DP said he had a bad experience before (with F900s) and I myself have never put the cameras under such conditions.

Going to another format is a viable option, but I'm just wondering if anybody has had experience with this before, be it good or bad.

Thanks so much!

Best,

-felipe.
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#2 Michael B McGee

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Posted 21 March 2009 - 11:31 PM

Shoot with an EX1 or EX3. it shoot cut well with the F35 footage.
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#3 Steven Polanski

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Posted 22 March 2009 - 04:01 AM

Have a plan B in place just in case on the day. this style of filming is not new to the industry and the manufacturers should have sorted this type of issue out before releasing this or any camera.

The only issue you will have IF AT ALL is the gyroscopic affect on internal spinning components when certain G forces are in effect. Shock dampening your camera mounts is also another issue.

Mount the camera at or below head height too ( refering to the sitting position in the ride etc). If it's a POV shot then obviously go hand held if possible. If you want to scare the SH..! out of the audience then solid mount the camera and try to eliminate as much camera shake as possible.

If in doubt contact the manufacturer or supplier and ask the specific questions.

I worked on the set of Charlottes Web and was amused by the ten or so crew members who were all trying to mount the small camera to the ferris wheel. None of them looked to me to have any great mechanical apptitude to realise that there needed to be a very heavy weight under the camera at a distance to prevent the resistance swing that they were getting. Evennnnnnnnnnntually it was sorted out!


Steve
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#4 Phil Rhodes

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Posted 22 March 2009 - 08:01 AM

I know that HDCAM tape decks (not sure if they were SR or not) were mounted aboard Hawk jet trainers used by the RAF aerobatics team, who were probably pulling at least +4g during a display, and they didn't give trouble. I'd still be tempted to have a backup plan, and avoid using mechanical devices like that at all if possible.

P
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#5 Brian Drysdale

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Posted 22 March 2009 - 08:31 AM

There's quite a lot of vibration on a roller coaster, which may be an issue more than the actual G forces. I know that the guys who mount cameras in rally cars suspend the video recorders to prevent this. I suspect the G forces in a rally car won't be any worse than a roller coaster. I know they're pretty strong in a saloon racing car - having filmed with Barry McGuigan driving.
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#6 Stephen Williams

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Posted 22 March 2009 - 08:43 AM

There's quite a lot of vibration on a roller coaster, which may be an issue more than the actual G forces. I know that the guys who mount cameras in rally cars suspend the video recorders to prevent this. I suspect the G forces in a rally car won't be any worse than a roller coaster. I know they're pretty strong in a saloon racing car - having filmed with Barry McGuigan driving.


Hi,

I have shot with an old Arri III on a roller coaster (Rental house would not let me use a 435) we did have problems with the video assist recorded to a DV clamshel recorder.

Stephen

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#7 Brian Drysdale

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Posted 22 March 2009 - 09:17 AM

Hi,

I have shot with an old Arri III on a roller coaster (Rental house would not let me use a 435) we did have problems with the video assist recorded to a DV clamshel recorder.

Stephen


I used my Aaton on one of those small roller coasters with out any problems, but the forces on one of the big jobs would be worse. I believe they used Arri IICs on that film "Roller Coaster".

I don't think I'd use the EX1 or EX3 on a roller coaster because of possible CMOS rolling shutter effects.
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#8 Paul Bryer

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Posted 07 April 2009 - 10:07 AM

Hi Felipe,

Vibration and G-Force can indeed cause problems for tape based recorders.
One option would be to use the F35 but with a solid-state HD-SDI recording device, such as the Convergent Design Flash XDR. No moving parts so impervious to vibration or G-Force.
It records in MPEG-2 4:2:2 (up to 100Mbps long-GOP or 160Mbps I-Frame only) to CompactFlash cards in either Quicktime or MXF file formats, so very high quality.

More info here:
http://www.convergen...ts_FlashXDR.htm

List of rental houses:
http://www.convergen....com/rental.htm


Paul

(In the interests of full disclosure: I work for Symbiosis, the European distributor for Convergent Design)
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