I've been working in an industrial shop and have the chance to shoot an arc welder. I've worked in this type of environment before and understand the dangers of arc welding and the human eye, so that isn't the question here.

I need to know if the arc will damage my sensor, and if so, under which conditions? Specifically, I'm concerned with a longer shutter speeds. I have an 8ND filter too.

If anyone has tips on how to capture this I'd like to hear those too.

Thanks.

I've shot arc welding on video. I have lit the heck out of the scene so I could shoot with ND and stopped down. I can't say about the sensor in a still camera, but long exposure to the arc will burn a video camera's chips.

Use a protective filter. I wouldn't use neutral density but you should keep the hotspot a little off center of the meter bias so it doesn't throw the exposure off.

If you're worried about damaging the camera, you could shoot it with a point and shoot. Here's an example I did with the CoolPix 990:

Unlike a video camera, the sensor in a DSLR is not exposed to the arc long enough for it to be damaged. Unless you're shooting at very close range, an arc welder is no more dangerous to the camera sensor than the sun. If you are that close, you should still be worrying about molten metal spatter from the arc damaging the lens more than the arc damaging the sensor. Spatters of molten metal can fly a few feet from the arc and melt themselves into metal and glass surfaces, leaving small craters in the glass when they are removed. A UV filter would be a good idea to keep your lens front element from being pitted.

The sun...that brings up a question that I have wondered about. Under what conditions, if any, of lens powers, aperature sizes, and exposure times could an APS-C sensor be damaged while photographing the sun directly?

More specifically, I have a Canon 40D.

I am not so much interested in photographing the sun as knowing to what degree care should be exercised if the sun is in the frame.

And, I suppose that a corollary question is the conditions under which my cornea could get burned while looking through the viewfinder.

Does anyone in the community know the answer to this?

Thanks,
Bruce

Not specifically. But don't use live view with the sun in the scene. (And watch your reflections.)

I'll be shooting with a shutter speed of no more than 1 sec and I always shoot with UV filters on my lenses, except when I have a polarizer or ND filer on them.

Here is an image I shot of a cutting torch recently. I'll most likely be doing the arc welding in the same shop.