I've read somewhere that mirror is held up by some electromagnetic mechanism, and hence will drain the battery quickly when using long exposure. Is that true?

It was also suggested to press shutter and take the battery out as I recall.

  • \$\begingroup\$ The shutter works the same as on DSLRs. \$\endgroup\$
    – Horitsu
    Apr 20, 2018 at 5:01
  • \$\begingroup\$ Somebody suggested to take out the battery? XD Sorry dude, this person made a joke on you, because it is probably impossible to remove the battery without shaking the camera, which is the least what you want. \$\endgroup\$
    – Horitsu
    Apr 20, 2018 at 5:03
  • 1
    \$\begingroup\$ @Horitsu well, you can put a lens cap on while doing this \$\endgroup\$
    – Valya
    Apr 20, 2018 at 15:11
  • 2
    \$\begingroup\$ While to my knowledge there are no EOS bodies that don't consume battery power during long exposures (remember too that the diaphragm is electromagnetically controlled on the EOS mount, not physically), there are plenty of bodies on many other systems (e.g. Nikon FM, FM2n) that can have their shutter left open for years, if you like, since the shutter mechanism and diaphragm are controlled completely mechanically. \$\endgroup\$ Apr 21, 2018 at 13:25

1 Answer 1


I don't have personal experience with the EOS 5 - but Bob does and his report is that your max is 6 hours before the battery runs out and the shutter closes.

You'll want to watch the temperature as well. If you're shooting skies at night in really cold temps - expect less battery performance.


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