Overhead Power Lines Cause Image Stabilisation Malfunction

Sorry for the long post, I wanted to describe the situation to rule out other factors such as faulty equipment.

At Castle Combe racing circuit in the UK, there is a section of the spectator area which is directly beneath overhead high voltage power lines.

Back in May, when I started taking photos there with my 40D and Canon 70-300 IS lens, I was seeing double when looking though the viewfinder with IS activated. The lens was also making a strange grinding noise when the IS was activated and the focus in AI Servo wouldn’t lock on. I thought that the lens was broken or that the contacts were dirty, so I took the lens off and cleaned the contacts. Still no difference.

Thinking my lens needed at trip to Canon for repair, I went to a different section of the circuit away from the power lines. When I tried the lens there it was back to normal, rock steady image and no focus problems.

The only thing I could think of was that the power lines were interfering with the lens.

I wasn’t able to return to the circuit to confirm my theory until yesterday. Exactly the same problem happened except the lens wasn’t making a grinding noise this time. I moved away from the power lines and the lens returned to normal.

To date I have taken 20,000 photos with my 40D, about half of these have been taken with the 70-300 and I have never had a problem, except when near the power lines.

Has anyone else experienced this at Castle Combe circuit or when near power lines?

if you want to test your theory, try the same but with a magnet close the relevant mechanisms. the only effect the power lines can have i due to their magnetic field...

I could see where power lines could induce some stray voltage in the lens - though I wouldn't have bet on it. I would very much like to hear more from others with or without the problem.

You may want to test it - see if it happens again, and then start moving away from the power lines 10 feet (sorry, 3 meters) or so at a time to see where, and if, the problem goes away.

inneresting... I wonder if it wouldn't affect a 70-200, more metal to sheield the electronics.. ... but if you think about it... there's a lot of small sensitive electronics very close to being out in open air on that lens.. it's not terribly surprising that some rf / em noise could mess with the signals..

hmm, interesting. Kinda makes sense. The power lines will produce a significant electromagnetic field, which could (maybe?) interfere with the electronics in the lens. As janvm mention you could test this with a magnet but I know I don't want to do that to any of my lenses.. Maybe if someone has a 18-55 IS lying around..

I doubt very much that a magnet will prove much of anything. Power lines, being AC, create MOVING magnetic fields. While in some cases a stationary magnet will cause problems, like, putting a magnet too close to a CRT, probably the only way to really test this is to get a second camera and at least one other IS lens and simply move around the track until you are satisfied one way or the other.

Because I'm a long time radio amateur, I'm VERY upset with the lack of enforcement on such things as interferance producing devices, and the FCC here in the states is uninterested. Virtually every single electrical device now sold in homes is capable of producing some sort of interferance.

My cell phone charger is one of the worst!!

you're right, i forgot about the ac part. In that case, it's not only the magnetic field you should be worried about, but also the microcurrents generated by the switching field.
Interference eh And it will get only worse:

Wireless electricity transfer

janvm wrote in post #6385594
Interference eh And it will get only worse:

Wireless electricity transfer

Looks like Tesla's vision may be becoming a reality.

Having worked on & in close proximity to HV gear i'd say yes, it most definitely can interfere with electronics. For a very simple demonstration just drive under a HV Overhead line with your car radio on an AM/MW station...what do you hear?

However, there's no need to take my word for it. Here's a quote straight from the National Grid website..

The roadrunner and Geoff are correct - there can be strong electromagnetic fields close to high voltage power lines.

A magnet won't simulate the situation at all, since its magnetic field is not alternating and therefore can't create an electromagnetic field.

Personally, I'd test it by using my bulk tape eraser (used for erasing reel-to-reel audio tape). It generates a strong 60 Hz EMF at close range.

I doubt anyone else has one of those, though. Well, maybe the roadrunner.

-73, KF6R