I just wanted to start a thread on what methods people find best for
B&W conversions?

I would also be interested in what techniques you use to get a authentic
photograhic look (grain, tone ect.)

I often use the Channel mixer to convert to B&W then add some noise on a 50% gray soft light layer. After I apply noise I blur it a little.

Facinating question...

FYI: This thread is a comprehensive collection of BW info and techniques, but does not address "What's your favorite method?" nor grain:
http://www.retouchpro.com/forums/photo-art-101/4769-tutorial-05-converting-color-image-black-white-grayscale-bw.html

Early on I used channel mixer, but seldom do anymore now that I have CS3, which has a spectacular BW adjustment layer. That (now) is my first tool of choice because it's so dang easy and there is more control than using Channel Mixer.

More times than not, however, I use a combination of the color channels copied as separate layers and combined using layer masks and blend modes. This method affords maximum control over the outcome because of its flexibility. The L layer (from a Lab version of the image) is used as a background. On top of that are layers whose sources are the R, G, B channels.

There are MANY convert color to BW actions at www.AtnCentral.com (http://www.AtnCentral.com) that simplify the layer setup.

Grain-wise, when I use it, I use the same method as you (layer set to Overlay [rarely Hard or Soft Light], filled with 50% grey, add noise to taste, adjust layer opacity). From most viewing distances, I don't really see the point though. Most people these days have never seen a traditional BW print (from film and printed in a lab), so IMO there's little to gain by adding simulated grain for this audience. I might add a little grain to disguise shadow areas to which digital noise reduction was applied.

My preference is to use the conversion tool in Lightroom. It gives a little bit mor functionality than that in photoshop cs3 in that is has 8 color sliders instead of 6.
For grain I tend to just use add noise on a new layer.

Thanks for the Links Danny!

Thanks for the Links Danny!My pleasure! :)

Also: There are some good articles on BW in the May/June 2008 issue of Digital PhotoPro magazine.

We do this for some VERY high profile photographers. Who insist on it being perfect. Even down to the grain structure. We do a slight amount of work digitally.... Then off to the LVT and output onto the emulsion they require. We even have old film stocks! There you go. Perfect B&W on Perfect grain structure of their choice. About 20 mins work charge em £500. They are happy... we are happy