Digital BW, The Print

Jules wrote:
>  There is no advantage to scanning a b&w neg in RGB as the three
> channels (and hence the three times larger file) will be identical.
>   
No actually, they won't be identical. Even B&W negatives have some level 
of color, usually depending on developer. HC-110 leaves Tri-X somewhat 
purple, while XTOL leaves Tri-X somewhat brown, for example.

The question is, is capturing this slight color cast worth anything? I 
personally don't think so, but clearly this going to vary depending on 
what the individual wants.

Now if you are working with one of the staining developers like 
Procat-HD, the stain contains image data and you should really think 
about scanning in RGB to capture this data. But I'm assuming a "normal" 
developer here.
> However, my printer tells me that i should supply him with RGB files
> of my b&w work as they contain more information. I have never quite
> understood this but I do it.
Theoretically this is true. A single scanner channel has less dynamic 
range than the three channels taken together. There is a similar effect 
with thermal noise in that more channels helps dampen scanner induced 
noise. But from a practical standpoint, especially with B&W negatives, I 
doubt the need for this. IOW, I believe that the three channels together 
contain more data, but not necessarily more information which is a 
different concept.
--
Bruce Watson