Beseler Dichro 23dga B&W contrast settings

[iamthejeff]

Hello

I have a Beseler 23C II fitted with a Dichro 23dga head. I want to make B&W prints and I don't have ilford contrast filters so I was going to use the color head to control contrast.

This Ilford page has comparable color head values for Beseler heads (2nd last page), but it has two separate tables for single color filter settings and dual color filter settings. Does it make a significant difference which I use with my enlarger?

Thank you!

 

[MattKing]

The dual colour settings are designed to provide some speed matching.
This means that as long as you are keying your observations to tones in the mid-tone to highlight range, using the dual colour settings will allow you to obtain similar results at similar exposure times when you change contrast.
The system isn't perfect, and tends to require additional exposure at the high contrast extremes, but it does give a good starting point for a new set of test strips.

 

[pentaxuser]

As Matt says, the dual filtration values work pretty accurately in the range of grade 2-3 and still not bad at 3.5 grade so for most negatives this is good enough unless you want to produce "fine art" prints. At least when I measured my exposure using a probe on the same spot on the negative projection this is what I found. However beyond those grades the differences become clear - even to people like me whose taste is all in the mouth as they say

Depending on what paper you use, Ralph Lambrecht has a sheet that gives the compensations necessary in 1/12ths stops and a stop table that converts the 1/12ths into figures using the base exposure you have decided is correct from the initial test strip.

pentaxuser