Videomaker – Learn video production and editing, camera reviews › Forums › Cameras and Camcorders › DSLR’s › 5D III or D800? › Hi siemajasiuu – if you want
Hi siemajasiuu – if you want a low light full frame camera, you don't want either of these cameras. You can save yourself some money and get better low light performance with a $2498 Sony A7s.
Here is what this camera can do in low light:
Unlike the D800 and 5D Mark III, the Sony has a viewfinder that works while you're recording video. It also records at 1080/60p and 720/120p for in camera slow motion – something neither the Nikon or Canon can do.
The Sony is a much better choice for video.
Hope this is helpful!