Zonemaster calibration with Ilford Multigrade 500 head

Have just bought a new Zonemaster ll and begun making the test strips for calibrating which has gone well up until now.

Calibration manual states: "If you are using a colour or variable contrast enlarger you will usually need to correct the exposure at grades 4 and 5 because standard above lens and below lens filters require an exposure increase at these grades. This increase is built in to the meter's basic calibration. Before you make the grade 4 and 5 test strips reduce the exposure setting by one full stop."

Neither of my enlargers (Durst Laboritor with Multigrade 500 head and Intrepid LED enlarger) need the user to program in additional exposure time for grades 4 and 5 and I am unsure about the meaning of the above paragraph.

I have asked the suppliers of the Zonemaster who thought I should try reducing the exposure but didn't really know.

Should I reduce exposure by one stop?

Yes, you should.

You can see so for yourself. While making test strips, if you bump the grade from 3 to 4 you see that the time on the ZMII nearly doubles and you are supposed to correct for that by reducing the exposure by 1 full stop. Or, in ZMII parlance, by decreasing it with 12 steps. Depending on your chosen step size you should press the downward exposure arrow 3, 4, 6 or 12 times. When calibrating, grade 4 and 5 need a -12 exposure adjustment.

If you have any further question, do not hesitate to make some noise ..

Good luck!

Thank you MrclSchprs, I can now proceed with confidence!