Converting to B/W in photoshop

[treeman]

Am I right in thinking that if I produce a B/W image from colour file, using photoshop by image - adjustments -Black and white, that the image should have no colour tones in it what so ever and any cast I see on my screen is down to the screen?

 

[Chappers]

The B&W image should be neutral. As you say all else being equal then any cast you get is probably down to the screen