Turning Off the Camera Before Changing the Lens

I am amazed that this issue has come up again regarding the Canon EOS R and RP cameras.

Apparently it's because people have noticed that the shutter is closed over the sensor when the lens is removed, unlike at least Sony, but I don't know if Canon is actually unique in this aspect.

What I haven't heard--perhaps someone with an EOS R can take a quick look at this--is whether the shutter closes when the camera is turned off or when the lens release is pressed. That seems to be the crux of this new issue: People say you must turn off the camera to close the shutter over the sensor.

But some other myths have come out of the woodwork, such as, "The sensor is charged when the camera is on, so it attracts dust."

Years ago, the late Chuck Westfall (who left a gap that has not been filled) explained why a CMOS sensor is not "charged" and in fact could not even operate if it were "charged."

The other myth (or rather, semi-myth) is that you need to turn the camera mount-down when changing lenses. That depends on the environment.

If you're in an environment where there is a lot of ballistic dirt--something is actively kicking up particles heavy enough to be "falling," then face the mount down. Ringside at a rodeo would be an example.

But in a quiet environment, indoors or out, dust particles in the air are non-ballistic. The particles are lightweight enough that air molecules keep them aloft. In that case, every cubic inch of air contains roughly the same amount of dust. It doesn't make any difference which way the mount is facing.

What I don't understand is people who use a blower on the sensor. Air that contains dust is being blown towards the sensor.
Now if the blower contained filtered air that would be better.

Perfectly Frank wrote in post #18815083
What I don't understand is people who use a blower on the sensor. Air that contains dust is being blown towards the sensor.
Now if the blower contained filtered air that would be better.

Plus, you would want to shoot pictures through filtered air.

Perfectly Frank wrote in post #18815083
What I don't understand is people who use a blower on the sensor. Air that contains dust is being blown towards the sensor.
Now if the blower contained filtered air that would be better.

I am one of those people who sometimes uses a blower on my sensors. . So you don't understand me. . Hmmmmm. . Maybe I can explain why I do what I do so that you can come to understand that which you don't currently understand.

I usually wet-clean my sensors when I want to clean them. . However, I only like to do a wet cleaning when I have a decent setting in which to do so, and when I am not feeling "rushed".

Sometimes, while afield, I will notice that there is a crapton of big chunky dust and fibers on my sensor. . I want to clean the bulk of this off, but only want to spend 15 or 20 seconds doing so. . And I'm afield, where there isn't a table to set my camera on and where the light is not conducive to seeing what I'm doing very well.

In such circumstances I will pull the rocket blower out of my shoulder bag, go to the "Clean Sensor Manually" thing on my camera's menu, press "SELECT", take the lens off and place it on a log or something, hold the camera upside down, and blow out the sensor and mirror box area. . Then I turn the camera off, put the lens back on, stick the rocket blower back in my pocket or in my shoulder bag, turn the camera back on, and I'm off and shooting again. . This process can be done in 30 seconds or so.

The point isn't to do a proper, perfect sensor clean - the point is just to get the real big obvious stuff outta there and to do it in about a half minute. . The proper wet clean can get done when I get back to my home or the motel room that evening. . That takes three to five minutes, and I'd much rather do it when I'm not in a hurry and do it indoors where I can see better and be cleaner and more organized about it.

Does this all make any sense to you? . Do you feel as though you understand one of the rocket blower people now?

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This is coming from a person with typical DSLR bodies - not mirror-less. I wouldn't say that changing a lens with the mount side down is a myth - rather simply being cautious. I do this and when outside changing lenses I always have my back towards the wind for protection. That said I don't turn my cameras off when changing lenses but do when mounting or removing a flash.

I did not get into full time photography as a young lad in large part because of my experience working for two pros. Both men were no doubt really good photogs, but the ideosyncracies on display drove me towards other pursuits. I will work my a55 off to get a shot right, but I am not going to over work or overthink something like a lens change or cleaning the dust off a front element. Just freaking do it and get on with it.

cristphoto wrote in post #18815147
This is coming from a person with typical DSLR bodies - not mirror-less. I wouldn't say that changing a lens with the mount side down is a myth - rather simply being cautious. I do this and when outside changing lenses I always have my back towards the wind for protection. That said I don't turn my cameras off when changing lenses but do when mounting or removing a flash.

You wouldn't want dust in the lens either, so you should change lenses with the lens mounts of both camera and lens facing down.

Left Handed Brisket wrote in post #18815159
I did not get into full time photography as a young lad in large part because of my experience working for two pros. Both men were no doubt really good photogs, but the ideosyncracies on display drove me towards other pursuits. I will work my a55 off to get a shot right, but I am not going to over work or overthink something like a lens change or cleaning the dust off a front element. Just freaking do it and get on with it.

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I completely agree, Brian.

The way we handle and care for our photography gear really isn't that important. . It doesn't really have an effect on the gear's longevity, and it doesn't have an effect on the images that we take with our gear.

Cameras and lenses are just tools. . The thing that matters is the photos we create. . The gear is nothing more than a means to an end. . So the only care that should be given is care that enables us to keep on shooting. . Any more than that and you end up being one of those loathsome people who is more into the gear than the photos.

All cameras need to do is to be able to keep taking pictures properly. . Period. . And it doesn't take much care or maintenance to keep the things functioning. . They are far tougher and more resilient than many people seem to realize.


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I try to teach my kids to take care of things, so that they learn respect for what they spend money on, and also for other people's items.

So taking care of gear is a good example for others, if you have kids, etc. I will usually periodically dust off everything too so that if I ever get caught in the rain, the rain won't wash that debris into the buttons and dials. Other than that, the only purpose to taking care of gear is to garner higher resale later.

RDKirk wrote in post #18815049
....

What I haven't heard--perhaps someone with an EOS R can take a quick look at this--is whether the shutter closes when the camera is turned off or when the lens release is pressed. That seems to be the crux of this new issue: People say you must turn off the camera to close the shutter over the sensor.

Anyone have an answer to this part?

- I tend to turn the camera off, but when I am rushed I often don't. I don't think I've ever told any one that they should? My only concern would be if I was a bit of a butterfingers and managed to A: trigger the shutter, while B; having something protruding into the housing, like a pinky, and getting the mirror smacked about.

- I tend to have the body facing down when I change lens, as with the heavier lenses I use, that is the way it hangs from the strap when I go to remove the lens. Why make it harder? How this became a must is not clear to me?

I’ve read that turning the power off, does not really cut the power to the camera. I’ve read this about 1000 times in this forum. So if this is the case, why turn the power switch off?

Frodge wrote in post #18815359
I’ve read that turning the power off, does not really cut the power to the camera. I’ve read this about 1000 times in this forum. So if this is the case, why turn the power switch off?

One thing it helps with is that, if IS is active while the lens is being removed, it can cause trouble with the IS unit; so, turning it off gives the IS a chance to have spun down. Much more of a "CYA" moment than anything else....pretty much the only time I turn off the camera is when my battery dies. 10 years on and it hasn't caused me any issues of note.

Frodge wrote in post #18815359
I’ve read that turning the power off, does not really cut the power to the camera. I’ve read this about 1000 times in this forum. So if this is the case, why turn the power switch off?

Turning the camera off, turns the camera off. The most common reason people believe this is not true is that when the camera is turned off, if you replace the Storage card and shut the card door, a light comes on. That does not mean the camera was not off.

When you turn the power switch to on, depending on the camera, all kinds of things activate, eg: Top and rear LCD, rear display, lens IS (in the case of EOS R).
The card door has a switch. This switch causes a small fraction of the camera's function to do it's job.
If you remove a lens with the camera off, again, there is some activity by the camera.

The caveats are:
Older Canon DSLRs had a clock battery. Newer bodies use the main battery to power the clock so even with the camera turned off, the power to the clock remains connected.
Bodies with GPS, if the GPS is enabled, depending on how long the camera is off and what interval you have the GPS set to update, the power will intermittently be supplied to the GPS. As power is being supplied to the clock, the clock will work like an alarm clock but rather sounding an alarm will activate the GPS.

A car analogy works here. Ignition switch can have positions: Off, ACC, On. Depending on car specifics ON will energise almost everything, ignition, engine computer, fuel pump etc.
ACC will keep power to the radio and cigarette lighter sockets. Off will cut power to almost everything. The central locking will have power applied so it can respond when required. So you could say "power is not really cut". If you were teaching or providing an explanation though, you would be specific and explain that the central locking is the only thing that does not have the power cut (and anything else depending on the car eg, clock, alarm etc)

CyberDyneSystems wrote in post #18815257
Anyone have an answer to this part?

- I tend to turn the camera off, but when I am rushed I often don't. I don't think I've ever told any one that they should? My only concern would be if I was a bit of a butterfingers and managed to A: trigger the shutter, while B; having something protruding into the housing, like a pinky, and getting the mirror smacked about.

- I tend to have the body facing down when I change lens, as with the heavier lenses I use, that is the way it hangs from the strap when I go to remove the lens. Why make it harder? How this became a must is not clear to me?

I will check in a couple of hours.

I read recently a Roger Cicala article that said he thinks some damage can occur during shipping if the lens is removed with IS ON. Roger rarely makes blanket statements and often includes the fact that he could be wrong. Generally I bet he's right and act accordingly.
(When he looked inside the EOS R he pointed out that the space behind the sensor seemed suspiciously like IBIS was either considered or would be coming in future bodies...)

Frodge wrote in post #18815359
I’ve read that turning the power off, does not really cut the power to the camera. I’ve read this about 1000 times in this forum. So if this is the case, why turn the power switch off?

That's true. You can test it at the lens contacts with a multimeter. The contacts that are powered stay powered whether the camera is on or off. The contacts that are off stay off. There's not even a momentary change as the camera is turned on or off.

The ON/OFF switch of the camera does nothing but tell the camera, "Ignore all other user inputs."