Scanned B&W Negs Not B&W in PSCS3

[pflower]

I have been scanning 6x6 B&W negs on a polaroid sprintscan 120 with some success.  My normal practice is to scan in RGB colour 16 bit and then edit in Photoshop. Obviously the negs have a colour cast out of the scanner but I have found that scanning in 16 bit colour mode gives better results than scanning in 16 bit greyscale.  Once in Photoshop I desaturate the image.  However some negs I notice that even when all colour information is discarded there is still a blueish-mauve cast in the 3/4 tones which is visible on my monitor.  This persists even if I change the file to greyscale or use the B&W adjustment layer.  This makes no difference to the quality of the prints - usually I print on an Epson 3800 in ABW mode.

This makes no sense to me.  How come I can see a colour cast in a greyscale or desaturated file?  the monitor is profiled and is fine (Apple Cinema 20inch) and shows other greyscale images, gradients etc. as perfectly neutral.

Just a curiosity - any ideas anyone?

[Jonathan Wienke]

If you convert the image to grayscale and are still seeing a color cast, your monitor profile is bad. Or else your color settings are screwed up so Photoshop isn't using it.

[pflower]

Well I have profiled my monitor with a Spyder and Optical. I can convert any digital file from my D2x into B&W and it appears completely neutral on the screen.  But with these negs  I can see the colours whether I use the profile created or one of the "canned" monitor profiles.  Also I can see the same colours in teh same areas on another computer/monitor - this shouldn't be happening and is beginning to intrigue/bug me.

  What do you mean by "my color settings are screwed up so Photoshop isn't using it"?

Thanks

[Jonathan Wienke]

Well I have profiled my monitor with a Spyder and Optical. I can convert any digital file from my D2x into B&W and it appears completely neutral on the screen.  But with these negs  I can see the colours whether I use the profile created or one of the "canned" monitor profiles.

Then you aren't converting the files to grayscale. If you leave the files in RGB then yes there is the possibility that there will still be colors, depending on the method you use to "desaturate" your image. There is no reason at all to keep a B&W image in a color format unless you want to use some kind of toning. If it's straight B&W, convert to Gray Gamma 2.2 or Gray Gamma 1.8.