Most of the time I'm shooting with a 5D III, but the 6D has the same size sensor with similar sensor performance (actually the 6D is just fractionally better) but at a lower price.
Incidentally, if you switch to any full-frame body (e.g. a 6D, 5D series, etc.) then you cannot use "EF-S" lenses -- those lenses are smaller, project a smaller image circle, and are designed to work with crop-frame bodies like your 1100D. Full frame sensor bodies require "EF" (without the "-S" suffix) lenses.
Incidentally, the reason Scotty is asking about your needs is because for somewhat similar prices there are camera bodies optimized for different uses. For example, the 7D II is an APS-C sensor body (the same as your 1100D) but is heavily optimized for action photography -- having an exceptionally good focusing system (63 point AF which is highly adaptable and tuneable to the situation) and has an extremely fast continuous burst speed. It's fantatic for fast-action rapid-shooting photography.
The 6D has a focus system similar to (but a little better) than your 1100D, but a better sensor, better at low light, but not optimized for fast-action photography. It's better for situations where fast-action isn't needed -- such as portrait, landscape, or most low-light situations.
BTW, there's nothing about "manual" mode that makes it better and sometimes it can be a detriment (if I'm shooting in a situation with rapidly changing lighting -- such as a concert situation -- and you wouldn't likely be able to keep up with the adjustments.
I'd encourage you to use all the "creative zone" modes -- Tv, Av, and M. I don't usually use Program mode but if I hand my camera to someone else I usually slip it into Program mode for them so they don't need to worry about exposure settings.
If you use Manual, but trust the light meter in the camera, then you set some aspect of exposure, meter, and set the other settings to bring the light meter indicator to the 0 mark -- indicating that the camera believes this would be a good exposure. But if you use Av mode or Tv mode, you're getting the identical shot in less time -- there is literally no advantage to using Manual -- not even a tiny advantage (even things like exposure compensation can be dialed in).
I do use manual in any situation where the light meter would not likely be effective. For example there's no point in using anything but manual mode for astrophotography since the camera can't effectively meter for the night sky objects (there's also no point in using auto-focus on the lens since it can't focus accurately on stars.)
If you're using any "manual" controlled flash (not a Canon E-TTL II flash) then the camera isn't going to know about these external flashes or how much light they'll provide -- that's another situation where the internal meter wont be effective and you should use manual mode.
But for most shooting situations, go ahead and use Av or Tv mode -- you'll likely find it's much faster and the camera is actually less likely to make a mistake setting exposure than you are.
Tim Campbell
5D III, 5D IV, 60Da
