Digital BW, The Print

I read several of the replies and they are all correct but I don't 
believe they addressed the exact intent of the question.

The replies all focused on using curves and channels to mimic the 
effects of putting different filters on the camera.

Unless I missed it, though, no one has addressed the issue that B&W 
film is not neutral in its response to the color spectrum.  Its 
pretty good compared with decades ago.  But my understanding is that 
it is still not truly panchromatic.

In other words the film responds slightly differently to red, green, 
blue wavelengths of light.  And each manufacturer creates films with 
slightly different response characteristics.  So desaturating in 
Photoshop yields an image which is different than what would be 
obtained by B&W film.  Using the channel mixer allows one to simulate 
the response of B&W film to different wavelengths of light.

Then there's the whole issue of film grain.  And even that has a 
Photoshop plug-in available.

Mike
--- In DigitalBlackandWhiteThePrint@y..., "millerhillsteve" 
<steverob@s...> wrote:
> I currently am using PS Elements as I can't afford Photoshop and 
frankly, my 
> prints are pretty damn good, but I've seen references to using the 
channel 
> mixer instead of simply switching the mode to greyscale. What are 
the 
> differences in desaturating an image when switching to greyscale?
> 
> Steve