High altitude, hard disk photography

I noticed that some cameras, such as the Canon HG-21, are not allowed, according to the user manual, to shoot above altitude of 3000 meters. This camera is recording on hard disk. The manual does not explain what happens if the camera does shoot above this altitude, or what happens if I just carry the camera with me above this altitude. Can I just shoot on the SD card instead of the hard disk? What's the damage? Any idea?

WOW not good at all. I live at 6,000 feet so every thing is up from there.

Sorry Don, I do not understand the answer. I need to shoot from an altitude of ~13,000 feet. I need to know, should I bother to bring my backup camera - the HG-21.

It was just a comment that I would not want a camera with that kind of restriction. I'm not sure why the limitation. It may be due to hard drive heat due to thinner cooling atmosphere at higher altitude. I always have a backup camera with me on all remote or off-location shoots. Best of luck.

Well, I understand the HD head "floats" in low pressure. The mystery is, is there damage involved, other than loss of data.

Disk drive heads do “float” on air, but not air at low pressure. It's low pressure air that causes the problem. The heads float – or more accurately fly - millionths of an inch above the surface of the disk on a moving cushion of air. The head arm acts as a wing. This air movement is caused by the disk platters dragging air with them as they spin around at several thousand RPM. Disk drives normally have a breather hole to equalise the air pressure to the same as outside the case, otherwise the case could deform as the external air pressure changes, which could damage the drive.

It's this breather hole that causes the problem at altitude because air leaks out of the drive. As the air pressure drops there is less and less air to support the head just above the disk surface, and as the air pressure drops the head will ultimately make contact with the platter. This is often known as a “head crash”, or HDI – Head/Disk Interference. A head crash will totally trash the drive.

There are drives available that are completely sealed for high or low pressure environments, and which are engineered accordingly. I have no info on these drives, but I would imagine they are more expensive as they would be engineered to withstand pressure changes. Aircraft would need to use such drives, for example, to ensure they continue working in the event of de-pressurisation.

There will be a bit of slack on the maximum altitude figure on standard drives to take account of natural variations in air pressure, as the drive will need to work at the maximum stated altitude even if there is a deep low pressure system in the area. I wouldn't risk it to see how far you can push it, though.

If you can completely shut down the disk drive in the camera you will be OK using it above the altitude ceiling, because when the drive is spun down the heads are parked, locked and are not near the disk surfaces. Just not recording to the powered up disk and using the SD card instead is not good enough, the drive has to be completely spun down. If you can't fully turn off the disk drive and record to SD card only, you will be able to take the camera above the ceiling provided it stays powered off.

Paul.

Thanks, I guess I have to remove the battery in high altitude. In addition, I realize I have another problem: I cannot copy the files from the CF card of the 5DII to a computer or USB HDD because of this reason. I will have to buy several CF cards, which will increase the cost of the expedition. Or maybe I can find an SSD (solide state drive) with SSD laptop. Hmmm, too expensive.