Hi guys, just to share my bw conversion workflow. I think its a rather quick and easy method that works pretty well. At least for me Basically it works the same way as the channel mixer method, just that you can see the changes directly as you move the sliders.
Original pic :
Step 1 :
Create a Hue/Saturation layer and set the saturation to -100
Duplicate the Hue/Saturation layer
Step 3 :
Set the 2nd layer to color mode