I accidentally had Noise Reduction on Long exposure turned on in my Canon Rebel T3i. I took a 2 hours exposure and then the noise reduction kicked in and I was banned from using the camera for 2 hours (was not fun in the cold). I switched the camera off but that was held off by the noise reduction process. Is there a way to force it to cancel?

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    \$\begingroup\$ Did you try taking the battery out? You'd probably lose your photo, but... \$\endgroup\$
    – Philip Kendall
    Mar 22, 2016 at 15:11
  • \$\begingroup\$ @PhilipKendall that I was afraid to do, I thought of taking the battery or the memory card out but I was afraid that I would corrupt the memory card or burn some circuit inside the camera \$\endgroup\$
    – K''
    Mar 22, 2016 at 15:12
  • \$\begingroup\$ If you corrupt the memory card that can almost always be fixed by formatting it (worst case: format on a PC then in the camera). If you do trash a card, well that's why I like more smaller cards. In this case though pulling the battery would be best. Cameras really have to be able to handle sudden loss of power. Again you just might have to format the card. It's unlikely though. \$\endgroup\$
    – Chris H
    Mar 22, 2016 at 19:06
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    \$\begingroup\$ @ChrisH trashing the memory card could mean the loss of any other photos on the card, which could be pretty bad depending on contents. \$\endgroup\$
    – Philip Kendall
    Mar 22, 2016 at 20:11
  • \$\begingroup\$ @PhilipKendall true but it's highly unlikely during an exposure. During a write would still be unlikely but not worth the risk. Once again: more smaller cards mitigates the already low risk (this Q doesn't appear to be about a pro situation where losing a specific shot from a specific time would be a serious problem). \$\endgroup\$
    – Chris H
    Mar 22, 2016 at 22:02

1 Answer 1


I had the exact same camera as you and experienced that too. There's no way to interrupt the process barring pulling the battery out. Even if you pull the memory card the camera will still try to save the image. Luckily the battery is easy to remove. Generally, the only photo to be corrupted is the one you were currently taking.

On a side note: try not to shoot exposures for that long, instead shot a bunch of shorter shots and stack them later. The reason for this is twofold:

  • If something goes wrong on a two hour exposure that's the entire time to waste. If the exposure was for a shorter time then you wouldn't have to worry as much.
  • While the camera sensor is capturing light it is heating up. The addition of heat like that will increase the sensor noise, resulting in a less desirable image.

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