This is how I generally do a b/w conversion: duplicate layer~ then on your channels window click on the red channel and select all and copy~ then back in your layers window desaturate the top layer then create a new layer and paste the copied red channel~ then set the blending mode on that layer to soft light~ then flatten.

Photo Info:
lens: canon 50mm 1:1.8
f stop: 3.6
exposure: 1/250