Magnetic fields

[NeilL]

I've been storing my camera, lenses etc in a unit in which I also have an electronic piano keyboard. This has two rather large inbuilt speakers. It dawned on me that these speakers probably generate a not insignificant magnetic field. I guess there are permanent magnets in the speakers, so the magnetic field would be ever present, and so potentially damaging to the electronics in my gear . My photo gear is two feet below the keyboard. How concerned should I be, and what exactly happens in the case that a magnetic field affects electronics? Are the consequences fixable?

Thanks for any info!

Neil

[bbeck4x4]

I've been storing my camera, lenses etc in a unit in which I also have an electronic piano keyboard. This has two rather large inbuilt speakers. It dawned on me that these speakers probably generate a not insignificant magnetic field. I guess there are permanent magnets in the speakers, so the magnetic field would be ever present, and so potentially damaging to the electronics in my gear . My photo gear is two feet below the keyboard. How concerned should I be, and what exactly happens in the case that a magnetic field affects electronics? Are the consequences fixable?

Thanks for any info!

Neil

I personally would not be worried, It's not like it's a tube tv with a screen that can take a magnetic field and mess up the colors, it's a solid state chip, If it were possible, the owners manual would warn us to keep it from stray magnetic fields.

[ziggy53]

It's fairly easy to use a pocket compass to determine relative stray magnetic fields and the distance in which they compare to the Earth's magnetic field.

Your main concern would be related to how your equipment is affected by the situation and proximity to the fields, if there are any present. (Some speakers have a "keeper" plate on one side which largely prevents much stray magnetics.)

First determine if you have a problem and the subjective amount of the problem. Use a compass and determine the distance at which any stray magnetics equal the Earth's magnetics, i.e. where the needle is deviated by 45 degrees. What is this distance? (The magnetic field in question should be in a level plane with the compass for this test.)

[Photoskipper]

Most of the modern electronic devices has some level of shielding against electronic or magnetic fields. such as the portable HD, CF cards and some sensitive chips. Unfortunately, no one will guarantee how much it can shield off and protect the device. You may wish to visit some of the technical site to find out the technical specification. (But I don't think I can understand those terms)

Just to play safe, store the camera a bit distance from the strong magnets.

[NeilL]

I personally would not be worried, It's not like it's a tube tv with a screen that can take a magnetic field and mess up the colors, it's a solid state chip, If it were possible, the owners manual would warn us to keep it from stray magnetic fields.

Thanks for your reply. Like you, I didn't think that I had seen any warning of this kind of risk in the camera manual (Canon 40D). However, your reply prompted me to check again, and lo and behold, there it is for the camera on p12, and for the CF card on p13!:huh

So, some risk there is, apparently!

[NeilL]

It's fairly easy to use a pocket compass to determine relative stray magnetic fields and the distance in which they compare to the Earth's magnetic field.

Your main concern would be related to how your equipment is affected by the situation and proximity to the fields, if there are any present. (Some speakers have a "keeper" plate on one side which largely prevents much stray magnetics.)

First determine if you have a problem and the subjective amount of the problem. Use a compass and determine the distance at which any stray magnetics equal the Earth's magnetics, i.e. where the needle is deviated by 45 degrees. What is this distance? (The magnetic field in question should be in a level plane with the compass for this test.)

Yeah, I might do that just to suss out the kind of distance where a magnetic field kicks in. Thanks!

[NeilL]

Most of the modern electronic devices has some level of shielding against electronic or magnetic fields. such as the portable HD, CF cards and some sensitive chips. Unfortunately, no one will guarantee how much it can shield off and protect the device. You may wish to visit some of the technical site to find out the technical specification. (But I don't think I can understand those terms)

Just to play safe, store the camera a bit distance from the strong magnets.

Thanks for your reply. Your take home message is spot-on, I believe. I have now done a little more searching around the topic, and seems like the effects on camera chips and CF cards are more likely to be of the nature of damage to the physical chip wiring, and the like. The worst cause is where a strong magnetic field is fluctuating.

So, as you say, be careful not to put your gear on top of CR tubes and Hi-Fi speakers, and near working vacuum cleaners and other powerful electric motors. As I understand it, magnetic effects fall off according to the inverse square law, so the closer to the source the huger the effect by much (:scratch:D).

[NeilL]

Ziggy, I followed your suggestion, and waltzed a magnetic compass around the house. The electronic piano keyboard I mentioned, has a magnetic field trailing off at about 1 1/2 feet. My photo gear was just outside that by a fraction of an inch, but the force would likely have been very weak even if they had been just inside, and not likely to have caused any problems. As well, the magnetic field would never have been fluctuating while the keyboard was stored in that unit.

Surprisingly, there is quite a hefty magnetic field around the 70-200 F4L IS - is there a magnet in those things?

N

[ziggy53]

Ziggy, I followed your suggestion, and waltzed a magnetic compass around the house. The electronic piano keyboard I mentioned, has a magnetic field trailing off at about 1 1/2 feet. My photo gear was just outside that by a fraction of an inch, but the force would likely have been very weak even if they had been just inside, and not likely to have caused any problems. As well, the magnetic field would never have been fluctuating while the keyboard was stored in that unit. ...

Anytime you move either the keyboard or camera you will cut through the magnetic fields and (potentially) generate current. I seriously doubt that there would be problems but it sounds like you might consider shielding if it is a worry.

... Surprisingly, there is quite a hefty magnetic field around the 70-200 F4L IS - is there a magnet in those things?

I would bet that there is a voice-coil actuator or 2, similar to speaker technology. This is common for rapid movement mechanisms like that in hard-drives as well. Hard-drives are very well shielded so I'm as surprised as you are to hear the lens is not shielded.

[NeilL]

Anytime you move either the keyboard or camera you will cut through the magnetic fields and (potentially) generate current. I seriously doubt that there would be problems but it sounds like you might consider shielding if it is a worry.

I have moved my gear, an easy solution.


I would bet that there is a voice-coil actuator or 2, similar to speaker technology. This is common for rapid movement mechanisms like that in hard-drives as well. Hard-drives are very well shielded so I'm as surprised as you are to hear the lens is not shielded.

I was thinking magnets might be part of the gyros(?).

[ziggy53]

... I was thinking magnets might be part of the gyros(?).

Here is an example of a Canon IS system and I believe that those magnets are part of the actuators that move the corrective optical element:

http://www.chrysis.net/photo/canon/tech/img/Image_Stabilizer.jpg

[NeilL]

Here is an example of a Canon IS system and I believe that those magnets are part of the actuators that move the corrective optical element:

http://www.chrysis.net/photo/canon/tech/img/Image_Stabilizer.jpg

Very interesting, ziggy, thanks!