EOS 5D Mark III ISO Button Not Always Staying Down

[jamiemac]

Hi, I have a workhorse old 5D Mark III and have noticed recently that the ISO button is proving to be less and less reliable. After pressing it, rather than always staying down for a couple of seconds so that the ISO setting can be changed, sometimes it releases itself instantly meaning that I end up changing the shutter speed instead - or alternatively have to hold the ISO button down at the same time as turning the wheel (which is incredibly tricky when adapting to changing light - I'm a live music photographer).

Sometimes it does work fine, which is in its own way just as frustrating, as you never quite know what's going to happen.

Is there a simple fix for this?

[jrhoffman75]

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@jamiemac wrote:

Hi, I have a workhorse old 5D Mark III and have noticed recently that the ISO button is proving to be less and less reliable. After pressing it, rather than always staying down for a couple of seconds so that the ISO setting can be changed, sometimes it releases itself instantly meaning that I end up changing the shutter speed instead - or alternatively have to hold the ISO button down at the same time as turning the wheel (which is incredibly tricky when adapting to changing light - I'm a live music photographer).

Sometimes it does work fine, which is in its own way just as frustrating, as you never quite know what's going to happen.

Is there a simple fix for this?

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The button doesn't physically stay depressed. When you press the button you start a 6 second timer to give you time to adjust the setting. Perhaps the switch is wearing out and doesn't always make contact.

[jamiemac]

Ah that makes sense - sometimes it stays on until the moment I adjust the wheel so it figures that it could be switch related then?

[jrhoffman75]

That would be my guess. canon doesn't service the 5D III any more, so you would need to find an independent shop if you want to pursue investigation and repair.