Blue, red, green or yellow densitometer channel?

[shannaford]

Hi all - trying to use an old densitometer to read my delta 100 negs, and not sure which colour to use. It has a dial on the front with four colours, red, blue, green and yellow, but no 'visual' cahnnel. I'm guessing yellow might be the visual channel, but only guessing. Any thoughts? (it's an old orange unit, Rollie 401T, or Rollmat or something like that).
Thanks

[Bjorn Nilsson]

Most of the darkroom materials, i.e. paper etc. are sensitive to blue, so use the blue channel.

//Björn

[ic-racer]

If I had that unit I would just take the filter out of the yellow channel (save it) and use that channel as the white channel.

Not sure about your machine, but on mine, the only difference between the color channels is the presence of a filter between the sensor and the film. In "white" mode the filters are removed.

[Mark Woods]

I believe Kodak recommends using the Blue sensor. It's what I use.

MW