I was thinking about incorporating some small but fairly strong rare earth magnets (like the smaller varieties shown here) into a camera bag for holding dividers in place, holding compartments closed, that kind of thing. I'm not aware of any warnings about keeping magnets away from DSLR's, but thought I'd ask here: Is it safe to store camera bodies and lenses near rare earth magnets?

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    Cant tell for sure but they would have to be fairly strong to cause interferance or corrupt data. I would assume if it caused trouble with other electronics (cell phones, tablets, laptops, etc), it would cause trouble with cameras. – Itai Jan 1 '13 at 18:15
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    It this better suited for skeptics.stackexchange.com ? – dpollitt Jan 1 '13 at 18:54
  • Have a read through this: superuser.com/questions/338641/… Technically I see no issues tbh. – Digital Lightcraft Jan 1 '13 at 19:29
  • To clarify, I'm pretty sure that the data will be safe. I'm more concerned about effects on thing like the mirror reflex mechanism, AF motors, and whatever other electromechanical things that might be found in a body or lens. – Caleb Jan 1 '13 at 19:43
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    Don't use CF Microdrives. – dpollitt Jan 1 '13 at 20:14

Given that you specifically state "small rare earth magnets" I can tell you the data will most definitely not be affected, but let me lay out my argument.

A magnetic field can induce a current - BUT this requires a pulsating magnetic field. Your rare earth magnets create a static magnetic field, so technically only if something moves in the magnetic field could a current be induced, but this would be very weak.

Secondly, while I believe the mirror is magnet driven, there is no other "magnet based technology" in use around a DSLR. CF or SD cards do not use magnetism to store data - harddrives and tapes did. Hence CF and SD cards are immune to magnetic fields (as long as these do not induce currents in the cards.)

Finally, magnetic fields do no penetrate very far. Magnets or electromagnetic field strength decreases proportional to the square of the distance. -> I.e. what is technically already a weak field (rare earth magnets are in practice not that strong relative to magnetic fields induced by coils for example where required) and they won't go very far.

Finally, many items nowadays use magnets for closing mechanisms - BlackBerry holsters have done so for ages, the PlayBook sleeve does too as does my Sony eReader cover. Heck, some laptops even have a magnetic closing mechanism and thus get rid of the button one used to have to slide.

On this basis I'd say it is pretty safe to use magnets around electric equipment without any issues. (Note: Don't do so next to an old cathode ray television, if you do you'll have to recalibrate the thing... but do these still exist? :))

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    For completeness, Pentax Share Reduction suspends the sensor of their DSLRs via magnetic force. In all likelihood, just like the mirror, there is no need for it to operate while in the camera bag. – Itai Jan 1 '13 at 20:26
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    Not that I disagree with you, but remember that the AF motors in most lenses probably contain magnets as well, not just mirror mechanisms. – Chinmay Kanchi Jan 1 '13 at 21:15
  • @ChinmayKanchi There are plenty of magnets or magnetic fields around us - we just don't realize it in many cases... the AF motors is a good point, though the magnets needed in a motor are even smaller and quite a bit weaker. I remember taking the Canon kit lens apart... they are tiny. – DetlevCM Jan 2 '13 at 8:24

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