I've just noticed a lot of dust on my sensor and I had to send my camera to the service center to get my sensor cleaned. I've noticed that when I use the mirror up mode "the function that prevents shake on long exposure", the shutter covers my sensor and I've been thinking would it be a good idea to up the mirror that way before changing the lens? I ask this question because I've been thinking since the sensor is covered with the shutter, then the potential amount of dust that can sneak through would be much less.

Would this have any benefit (or would it cause damage to the camera on the other hand)?

  • If you don't take 10minutes to change a lens, it shouldn't have any impact at all. On the contrary, I don't think it's a good idea to change lenses while using the mirror lockup function. When I change mine, I always turn my camera off, change the lens and start it up again. Doesn't take more than 5 seconds. I was taught to not mess with electronics when they are powered on. I didn't need to clean my sensor in about 9 years, so I guess I take care of mine well enough...
    – walther
    Nov 7 '17 at 10:39
  • @walther: Use the white screen method to see if there is any amount of dust. (at f22 or higher and at low shutter speed and ISO 100, adjust the exposure in a way that you get a little overexposed, and shoot a white and bright object while bringing it out of focus). And in lightroom, bring the darks to minimum while adjusting the lights. Please if possible share the result, I would like to compare with mine. Nov 7 '17 at 10:42
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    @walther Please don't post answers as comments.
    – mattdm
    Nov 7 '17 at 13:47
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    You don't even mention what camera you're using, so there's no way to give an exact reply.
    – Mike Dixon
    Nov 7 '17 at 16:19
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    @mattdm, I appreciate your point of view, but if you feel the comment doesn't fit the schema, feel free to report it and have the mod remove it if he/she sees fit. As you surely know, SE sites highly discourage extensive debates in comments, especially those totally off-topic and not even related to the original post.
    – walther
    Nov 7 '17 at 17:25

Mirror Up mode just separates the two stages mirror and shutter action that happen before and during an exposure. In normal drive modes, when you press the shutter button, the mirror flips up and the shutter curtain opens and closes right after that. In Mirror Up mode, you press the shutter and the mirror flips up, but the camera waits for another shutter button press to actually open and close the shutter curtain.

Changing the lens this way would only mean that the mirror is not in its "resting" place (and rather flipped up instead) which could mean that dust can potentially enter closer to the sensor. It makes no sense, plus there's no reason to do it, especially if the camera manual doesn't say anything about it (I haven't ever seen anything related to that in a manual).


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