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You Are Here: Home > Gear > Modifying Cameras > A2E Command Dial



Background Information: The Canon EOS A2E (and it's variants, the EOS 5 and A2) is generally a very reliable camera with the exception of it's Command Dial which has a reputation of failing, leaving the camera stuck in whatever mode it was in at the moment of failure. The problem is caused by a defective design where undersized plastic shear pins break when users forget to depress the release button while rotating the Command Dial out of the Lock position or simply from fatigue under the repeated stress caused by rotating the dial against the click detents. The following modification offers a way to permanently fix the defect by replacing the plastic shear pins with metal screws and removing the click indexing system.

It is possible to leave the click indexing system intact or reduce the stress it creates by shortening the spring but it is recommended that the system be removed altogether for 2 reasons. 1) The plastic channels that guide the bearing tend to wear at the corners causing the bearing to wedge itself between the plastic and the detent cap making it very hard to rotate the dial. 2) Any play in the ruggedized screw-mated dials will accelerate the wear of the plastic channels and vice versa. Eventually, the 2 problems can compound each other leading to seizure of the dial. Since determining which mode you are in without the click indexing system will be slightly more difficult, you should decide if you think it is worth sacrificing before attempting this modification.


1) Disassemble the A2E.

2) Locate the thin blue wire that comes out the front of the top cover from near the flash pop-up button. Desolder it from it's grounding point near the lens release button. Be careful not to keep too much heat on the metal surface or it may damage the nearby plastics or electronics. Instead, make sure the iron is already hot and quickly melt the solder with just enough heat to desolder the wire. This wire is being removed to allow us to move the top cover around more freely.

3) Remove the screw that lies at the center of the command dial's base.

4) Remove the metal piece held down by the screw from step 3. This is the latch that locks the dial when it is in the "L" position.

5) Notice the round bottle cap shaped metal piece on the underside of the Command Dial. If your Command Dial is already broken, you should be able to remove this cap by pulling on it. If not, lightly scrape away at the heads of the 2 plastic shear pins which hold it in place until the cap is free. Since the metal cap is not symmetric, make note of how it is oriented with the Command Dial. You will have to reattach it the same way later on.

6) Under the metal cap, you should now be able to see a small spring and ball bearing used for the click indexing system. If you wish to remove this click indexing system to decrease the chance of the dial failing again, remove the spring and bearing.

7) Take the detent cap to a hobby or jeweler's store and find small screws with diameters just large enough to pass through the 2 holes in the caps where the shear pins used to go (Sorry I cannot spec the screws since I did this modification 7 years ago and did not make note of it). Lengthwise, the screws should be roughly ~4 millimeters long and they should be flat-head screws since you want a low profile head to accommodate the limited space.

[Update: Glenn Riggio was nice enough to write in after performing the modification on his A2E. Based on his tests, he recommends using M1.4 x .3 x 3mm screws and a .043" drill to pilot the holes.]

8) Find drill bits slightly smaller in diameter than the screws. They should be small enough so that the holes they drill in the plastic end of the Command Dial will be a tight fit for the screws you bought in step 7.

9) Attach these drill bits to a finger drill or a small hand drill and drill out the plastic shear pins and into the command dial down deep enough to pilot the screws you bought. You may want to place the metal cap back on when drilling to use as a guide. Pull out and repeatedly check and measure to make sure you don't drill all the way through the Command Dial. Do not tap the hole, you want the fit with the screw to be as tight as possible.

10) Blow off any bits of plastic from the drilling and assemble the Command Dial onto the top cover again and screw down the metal cap to the underside of the dial using the small screws you bought. Make sure it is oriented with the dial the same way as you noted in step 5.

11) Reattach the metal locking mechanism from step 4.

12) Resolder the wire from step 2 to it's grounding point.

13) Reassemble.

Your Command Dial is now ruggedized and should not fail under normal use.


DISCLAIMER: The following information is for informational purposes only. No guarantee is made or liability assumed regarding the following information. Modifications you make to your camera are taken at your own risk. Because mistakes may result in permanent damage to your camera and any disassembly will void your warranty, it is strongly recommended that no attempts be made to modify cameras if you are not experienced in working with similar devices and unwilling to take the said risks.



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