Main Dial stopped working in Canon t4i/650D

[Josephkcs]

Hi,

The canon 4i/650D has been used very lightly. Last week, the main dial stopped working. I just swapped the lens and then i noticed that aperture setting is not changing when i move the wheel. I have called the customer support and he was not help ful. Please let me know if there are any suggestions. 

[amfoto1]

Some things you should check...

First, is your lens fully turned to lock in place? I've seen situations where that wasn't the case and it was impossible to adjust the aperture.

Next, you might want to try remove it and clean the gold contacts on the rear of the lens. Some will tell you to only use pure denatured alcohol or even a pencil eraser... I don't recommend the eraser because if there are problems with connectivity, it's often due to oils and pencil erasers are made from vegetable oil! I also think cheap and widely  isopropyl "rubbing" alcohol works just fine. 

Put a few drops fo the alcohol onto a clean, lint free cloth and gently wipe those electronic contacts.Just dampene the cloth and be careful not to touch the optics or get the alcohol onto other surfaces where it might remove paint or otherwise do damage. Also check the corresponding "pins" just inside the front of the camera. These are lightly spring loaded and should press down very easily with gentle pressure and then pop right back out. Look for any that are "stuck" pressed down into the hole, so that they won't make proper connection with the contact on the rear of the lens. Again, be careful to not touch the mirror or other things inside the front of the camera. And both the pins and the contacts are gold-plated to insure a good connection, so never use anything abrassive on them, that would possibly damage the plating.

I can't think of any settings that prevent the main dial from working... but I don't use a T4i/650D so cannot be completely certain. You might also do "factory default" resets of the menu and custom functions. This will undo any other settings you've made, though. So you'll have to redo those.

You also might update (if needed) or reload the camera's firmware. This is a little more complicated and needs to be done careful.... if you look up support for your particular camera on the Canon website you'll find the latest firmware version available for download, as well as instructions how to do it properly. This might "correct" come fault that's developed in a the current firmware. But, I gotta say, this a long-shot.

Finally, you might try a different lens on the camera. If you don't have a second lens yourself or can't easily borrow one, you might be able to use a demo lens in a store for a quick test. If the other lens works properly, there's a problem with your lens. If the other lens also doesn't work on your camera (or if your lens works properly on another camera), then the fault lies with your camera. In either of these cases, and if the things suggested above don't help, you'll probably need to contact Canon service dept. or another repair facility and have them look at the camera and/or lens.

Note: most modern electronically controlled lenses have a "flex cable" - a small bundle of wires - in the rear, leading from the external gold contacts to the various motors or other electromechanical devices in the lens, to conduct the controlling voltage. Those cables are flexxed every time the lens is zoomed and./or focused. Over time one or more of the conducting wires in the cable can snap or loosen, breaking the circuit that allows the camera and lens to communicate. This is the most likely fault. But there also can be failed components inside the camera. It might even be a failed main dial mechanism, though I really think that's pretty unlikely..

Hope this helps and it's something simple, easy and cheap to fix!

***********

Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2) some other cameras, various lenses & accessories
FLICKR & EXPOSUREMANAGER 

These are things you can do yourself easily and for free..

[Josephkcs]

Thanks for your response. I just checked the different lens (prime lens). Problem persists. I would try cleaning and the firmware update. I have the older version on mine so I would update and check it.

[ScottyP]

What mode are you in?  The main dial does different things depending on what mode you are in.  

In Av mode the main dial would move aperture.  In Tv (and as default in M) it would move the shutter speed.  Even in AV mode the main dial will also act on other variables (AF point selection, WB, Shutter Speed, EC, FEC, etc.....) if you have selected them in the menu or the  Q menu.

[Josephkcs]

Thank for your response. Yes, I was in the AV Mode when I noticed it. However, the touch screen is working and i was able to change the aperture.

[ScottyP]

Hopefully this is not a fatal issue.  Paying to repair an out of warranty older model of Rebel likely doesn't make sense.  At least this could be a good reason to upgrade to a T6i/T6s.

Those cameras were by far the biggest model-to-model upgrade the Rebel line ever made, and the rumor sites (and historical timing) say the T7i/T7s should be announced in about January, so you should see some discounts on the T6i/T6s.  

[RobertTheFat]

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@ScottyP wrote:

Hopefully this is not a fatal issue.  Paying to repair an out of warranty older model of Rebel likely doesn't make sense.  At least this could be a good reason to upgrade to a T6i/T6s.

Those cameras were by far the biggest model-to-model upgrade the Rebel line ever made, and the rumor sites (and historical timing) say the T7i/T7s should be announced in about January, so you should see some discounts on the T6i/T6s.

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Does the rumor mill think that Canon will go another round with three Rebels in production at the same time? Especially with the M series arguably starting to crowd the Rebels at the high end.

[ScottyP]

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@RobertTheFat wrote:

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@ScottyP wrote:

Hopefully this is not a fatal issue.  Paying to repair an out of warranty older model of Rebel likely doesn't make sense.  At least this could be a good reason to upgrade to a T6i/T6s.

Those cameras were by far the biggest model-to-model upgrade the Rebel line ever made, and the rumor sites (and historical timing) say the T7i/T7s should be announced in about January, so you should see some discounts on the T6i/T6s.

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Does the rumor mill think that Canon will go another round with three Rebels in production at the same time? Especially with the M series arguably starting to crowd the Rebels at the high end.

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Yes it does. We'll see. 

[Josephkcs]

I have upgraded the latest firmware and the issue still exists. I guess its the wheel itself that is damaged. I am really surprised. most of the time, i have used the camera in the auto or any other pre-programmed modes. I haven't turned the wheel so much and the camera was never dropped. Atleast, I can use the touch screen to make changes to the variables.