Aperture Lock button on 6D

My camera the Canon EOS 6D has a button in the back where you can use it to lock the Aperture and I think the ISO. Once engaged the flywheel is locked and you can't change Aperture/ISO values even if you tried. Yesterday though, I was on a shoot where the client wanted a series of pictures with the aperture set a f8, or f9. I chose f8 locked the aperture and forgot about it.

 

During the middle of the shoot, I noticed that the aperture had mysteriously changed from f8 to f6.3, then to f5. This meant that I had to shoot a whole series of pictures over again. Lucky for me I noticed in time, or the whole shoot would have been blown ! I tried to re-create the problem when I got home, but was unable to. My guess is that turning the camera OFF somehow reset the settings, but I'm not sure ?

I have a Canon 6D with a lock switch too but I've never used it. My camera ' function lock' settings (C.Fn. III-3) are the default ones which means the 'function lock switch' only applies to the 'quick control dial (rear wheel) but not to the main dial (top wheel) or multi-controller (the area inside the rear wheel). Under the C.Fn. III-3 settings, you can select which dials you want to be locked. It's worth checking these settings.

 

If they're not what you expect then my guess is that what is 'locked' by the switch depends on your shooting mode: aperture priority, shutter priority or manual. The manual doesn't give any information on whether previously locked exposure settings are reset when the camera is switched on/off. My guess is that they aren't (given that my previous ISO and aperture priority settings are 'remembered' when switching on the camera).

 

Hope this helps,

 

Mike

The lock only locks the rear dial, nothing else. So if you are on aperture priority and you flick the front/top dial you change the aperture value. In general in an automatic mode (Aperture or shutter priority) the rear dial is for exposure compensation, and since this wheel is easily moved when handling the camera, the lock helps prevent this. If you are shooting in manual the rear dial will usually be for shutter speed. A lock for all the buttons I think would be a good idea, but Canon have not provided that, so you do need to be alert.

Here are two filmstrips of pictures i took yesterday. For some reason the aperture changes from f8 to f6.3. Lucky for me I caught this one in time but I still had to recapture a series of pictures. This is happening when the camera is set to Lock meaning you are not supposed to set the aperture ?

 

Robin gave the answer. The lock switch locks the dial (makes it have no effect), not the aperture.

Robin gave the answer. The lock switch locks the dial (makes it have no effect), not the aperture.

No, actually the Lock is supposed to lock the Aperture which is connected to the wheel when you are in Manual mode. I think I solved the problem though. At first I thought it was my Pocket Wizards, but then I realized that I didn't have the Pocket Wizards on or near the camera when I was outside.

 

The next thing that came to mind was the Remote Switch which I had dangling from the camera. Not the newer RS60 model, but the older model: Canon Remote Switch RS-80N3|Canon Online Store . I took it off the camera today and had no problems with the aperture switching back and forth. My remote switch is over 15 years old ! it was one of the firs accessories I purchased for my Canon. It could be it's getting a little long in the tooth...

The issue is you never said you were shooting manually. It only locks the rear dial, however you have set the camera.