Known to many of us - Carr Mill Dam, near St Helens, taken while playing with an ancient Helios 28mm f2.8 lens. Carr Mill1 by Mick Finney, on Flickr
Nice. Soft shades here. I'd have been tempted to miss your point entirely and boost the contrast some more. I was last there on Boxing Day: time flies.
Oy and Polly - original colour version here. I still prefer the mono. Carr Mill2 by Mick Finney, on Flickr
I prefer the colour in this instance. The old lens is still doing its job well. Which adapter are you using on the 5d Mk3? I've tried my old manual focus Canon 50mm f1.4 fd on my 5d mk2 and it doesn't work at all can not get it to focus on anything near or far, with the eos to fd adapter.
I'm afraid I prefer the colour version the mono does need more contrast or perhaps a little assault with the burn tool?