5D Mark III help

Hi,

2 of our 5D Mark III's all of a sudden both started acting up. Changed the internal battery on both thinking that might fix them. When we turn them on the top screen will show everything is working but the main screen stays black and will not shoot. We change batteries and lens and will work for a bit but then go back to the same issue. Do it again, and nothing will work, then try again and goes back to the dark main screen with top screen working. Have never cleaned the connections ever between lens and body but thinking maybe. If so what would you use to clean and any thoughts on what we could do other then send them in for service.

Thanks for any help.

I’d be checking that main battery or perhaps the charger you use. Even though a battery shows a full charge it may be weak, and the first thing to go is one or both of the displays because they draw the most power. So check the battery status in the camera or get another battery (buy/borrow) that could be used for test purposes.

Thanks very much, really appreciate it. Will do.

The internal battery is not (AFAIK) connected in any way to the rear display. But it *is* related to retaining settings between (main) battery swaps. Are your camera settings retained between main battery swaps? For example, the current time, exposure settings, etc?

Also, you cited that the body was acting up before changing the internal battery. Did the "acting up" include things like forgetting settings? Or was the display part of what was acting up?

My first thought on any such description (about a body acting up) is electrical failure. That's a much less pleasant consideration, I know.

Hi, yes they were keeping the time and date correctly. I just never changed those after all this time and thought maybe when removing the main battery if those were weak, it could cause an issue of some kind so changed all of them.

The good news is that I used one of our best most recent batteries we bought in both camera's and surprise, they both worked. We have so many batteries and have had them for a long time so I guess the batteries I used in the camera's that did not work were just too old and just wearing down to where they just aren't as powerful after a charge. They did hold up a long time.

Thanks so much John for the help, It worked. And thanks Dasmith for also helping and suggestion. Appreciate it very much.