Här kommer lite ytterligare tips som jag hittat!
B&W conversion has always been an interesting topic. As you can see from your examples, Greyscale and Desaturation methods don't always give the best results. The Channel Mixer can be used for many effects including B&W conversion, and lends itself to personal tweaks to give differing outputs.
The main rule to remember, if you want to retain normal luminance, is to ensure that, whatever settings you have on your CM sliders, they should add up to 100. This still allows a lot of scope for customising slider positions to give the best B&W conversion for any given image.
You can also replicate certain film types.
Here's a few examples...
Agfapan 25 : 25,39,36
Agfapan 100 : 21,40,39
Ilford FP4 : 28,41,31
Ilford HP5 : 23,37,40
Ilford Pan F : 33,36,31
Ilford SFX : 36,31,33
Kodak Tri-X : 25,35,40
You can also emulate B&W lens filters...
(the 100 rule doesn't apply here)
Red : 100, 15, 0 (constant -15)
Orange : 75, 20, 20 (-15)
Yellow : 60, 30, 10 (0)
Green : 35, 55, 20 (-10)
Blue : 15, 15, 80 (-10)
Infra Red : 120, 32, -64 (10)
