5D mk iii no focus preview

[hannahmia]

Hi

Today my 5D mk iii just stopped showing any of the focus previews in the viewfinder, there are no longer any red lights and the whole thing is significantly out of focus. The focus is actually still working, as the images seem to be in focus. I couldn't find any indication of settings being changed, but I reset the settings and the beep (which I usually have off) did work when focusing. I checked that I hadn't accidentally moved the diopter and that seemed to be in the right place too (as it gets even worse when I move it - and also wouldn't explain why the red lights have gone). Changing out batteries and lenses made no difference either.

Any ideas on this and how to fix it?

thanks! 🙂

[Waddizzle]

Using a fresh, new memory card is a cheap fix.  It never hurts to have an extra spare card on hand, anyway.  Be sure to format new cards in the camera.

As far as no focus preview, it is possible that your button has been reprogrammed and repurposed.  Resetting button programming is an entirely separate reset.  To fully reset a your camera to factory defaults, there are at least three places in the menus where you must do a reset.