From the Leica M Typ 240 / M240 user manual:
Sensor — Cosmic Radiation can cause pixel defects.
Please remember that the next time you travel to the moon. I think it’s cute that Leica has included this important note in the manual. I’m not aware of any other camera vendor that bothers.
Seriously, flying in an airplane or traveling to high elevation subjects you and your camera to a substantially higher risk of a few cosmic rays than at sea level. Computers are subject to “bit flips” for the same reasons.
Jeff H writes:
Oh yes this is true.
It used to be that when I flew with my D3x, it ended up with a couple dead pixels per 10,000 miles which after a while I took to Nikon Ginza to map out. After a few round trips, it got me thinking. Perhaps X Rays, Cosmic Rays, Radiation etc can zap the circuitry. Otherwise how would these damages occur? With the D3x priced at what it was, I could not take any further chances.
Soon I crafted myself 2 pieces of 8x10 Lead sheets which I wrapped the Camera + Body Cap (sans the Lens).
The security X-Rays are also a source of potential havoc, so first time thru, the Lead wrap would always elicit an open and search.
Although I never had any problems with the guards, the X ray safe shield bags for Film from the yesteryears may raise fewer eyebrows at airport security.
Mind you I think the D3x was more sensitive to this and was more prone to stuck pixels than other cameras.
I had a gut feeling that operating Live View also aggravated this problem but was not able to verify which was the major contributory cause.
On the same note, I think sensors of today are more resistant, and less prone such errors now. Although depending upon the pricing of future D4x and likes, I may want to continue to err conservatively.
DIGLLOYD: interesting anecdote!