^^ ^ Agreed. The panning control should only be active for mono tracks, say if someone were using this as a field mixer and recording an interview with a boom and a couple lavs all as iso tracks - I'm thinking of a mixer like the SD 302 which was probably designed for situations like this. Someone doing a recording like this would know to record iso mono tracks, and would not use the stereo mode. The 70D doesn't record a separate stereo downmix, unlike many pro recorders.
Selecting stereo mode should deactivate panning and lock the odd/even channels hard L/R respectively, since a proper stereo track would be hard-panned by definition. Anything less than a hard pan would create a recording closer to mono, since you'd be feeding some of the L channel to the R and vice versa.
I think I'll add this to the FAQ as a "known issue". I guess it's not really something that's broken in terms of functionality, but is something that could potentially mess up a stereo recording if you accidentally move it.
It would seem to me that Panning is concept that only applies to stereo...
When you record in mono - you get 2 files (or 4)...there's no where to pan to...
Long ago - I used a mixer for 4 channel recording - when running stage mics - sometimes I would set them very far apart - but pan them together slightly so they weren't so LEFT RIGHT-ish...
OK, I see how I'm making a false comparison here and somehow I got my thinking backwards. On something like the SD 302, the panning for the 3 mono tracks is useful because that unit is outputting a stereo mixdown of the 3 inputs. On the 70D though, there is no such mixdown. Because of that, all of the signal from one input is going fully to one recording channel no matter what the pan says, as opposed to a stereo mix which would either send the signal to L or R only (hard-panned), split equally (center pan) or somewhere in between.
Or to use an example I have more direct experience with: My FP24 has L/C/R switches for each of its two input channels. If the CH1 input is switched to "C", that input signal is routed equally to both output channels. I have to set the two channels to L and R in order to get a stereo recording.
I had to answer this for myself, and hooked up a pair of mics. I tried panning each mic to hard opposite to create mono-two-channel in stereo mode, but, stereo imaging remained.
OK, but doing that, I would expect that you'd still get stereo separation because you're still hard-panning; just backwards. I think the way to test this is to center-pan each mic channel while recording in stereo mode. That should result in a mono image because the CH1 mic signal would be split equally to both L and R tracks, and same thing would happen for the CH2 mic. (see above)