[Brightcolours]

I could not care less about shallow DOF (quite the contrary, to be honest - I hate this side of using large aperture lenses when actually shooting what I'm shooting - it's impossible to do any group portraits for example - but I appreciate getting a little bit more light). F/2.8 primes for my Canon make little sense to me because I have a 16-35/4 IS so when I'm not scrambling for more light, I'm just using this, whatever the circumstances. Why lug around a lens that gives you almost nothing worthwhile?

 

 

Yes, that was me. So I would be getting a bonus of a wider actual FOV. Again, something to think about.

You don't get more light on MFT at f1.4 than f2.8 on FF, though... And ISO can be set to whatever the situation asks for.

Trying to guess why MFT + this 12mm f1.4 lens appears so interesting to you, while you use a big DSLR with well spaced controls. Is it just the weight? It can't be the ergonomics.

Nor the size of the lens (as pointed out, it is not really small nor light).

 

Just as curiosity remark: Easy, cheap and light way to have 18mm on the 1D mk IV is to put a EF-S 10-18mm f4.5-5.6 IS STM on it.