Lately I have been having trouble adjusting my aperture when my 5 d mark 2 is in manual mode. Usually I am able to turn the thick dial at the back of the camera and adjust the aperture. Lately this is not working. In other modes the dial works fine. Is it my camera? Or have I accidentally changed a setting?

  • \$\begingroup\$ Are you trying to set the aperture to be bigger than the max. aperture of the lens? \$\endgroup\$
    – inkista
    Commented Jun 14, 2015 at 18:24
  • 1
    \$\begingroup\$ The 5DII has two control wheels. When in Manual exposure mode one controls Tv, the other controls Av. \$\endgroup\$
    – Michael C
    Commented Jun 15, 2015 at 9:59
  • \$\begingroup\$ @thomasrutter If you have a guess that might be an answer, best to submit it as one even if you're not sure. That way it can be voted up or down by people who know -- and it doesn't come in above other answers, as your comment does now. \$\endgroup\$
    – mattdm
    Commented Jun 16, 2015 at 0:17

3 Answers 3


This is a very common issue with the 5D series. You have accidentally locked the rear control-dial. The power-switch next to it has actually 3 positions. When lined up with On, the camera is on but the rear control-dial is disabled. When lined up with the white line which goes to that dial, the camera is on and the dial is enabled.

  • \$\begingroup\$ Thank you. Just got my 5D, and was wondering about the difference between the line, and the 'ON' position. \$\endgroup\$
    – zero_cool
    Commented Mar 20, 2016 at 17:51
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    \$\begingroup\$ thank you. that was it for me. I had the lever set to "on". had to move it up one more notch. the fact there is 3 postitions to this switch escaped me for all these years. \$\endgroup\$
    – golferstub
    Commented Nov 10, 2016 at 15:22
  • \$\begingroup\$ Thank you, the F-Stop works fine now. On mine, there is a lock switch right below the dial. I went from "Lock" to full left and I'm back in business. \$\endgroup\$
    – Bill
    Commented Dec 23, 2016 at 2:15
  • \$\begingroup\$ thank you from me too. i thought the upper one was a lock. Wrong. Laura \$\endgroup\$ Commented Mar 31, 2017 at 0:23

The other cause for this, apart from the POWER SWITCH setting, is found in the CUSTOM FUNCTIONS SETTINGS of the camera MENU.

Go to "C.Fn III:Autofocus/Drive" and select "-3". You will see three options:


1:Multi-controller direct.

3:Quick Control Dial direct.

Select "0:Normal" and this will free up the Quick Control Dial for aperture setting in manual mode.


For the Canon 5D MkIII, this worked for me: Go to C.Fn2./Disp/Operation, select Custom Controls, select DOF preview button, Assign Depth-of-field preview, set.

  • \$\begingroup\$ This is completely off topic. Different issue, and different camera. \$\endgroup\$
    – bogl
    Commented Mar 31, 2017 at 7:46

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