That makes perfect sense. Thankyou. I now understand what Bill was trying to tell me. And by metering different parts of the test neg, I can get an idea of the ranges in play too, which should teach me more about judging the densities of any given neg - which I am still having trouble with. I will give it a try. And I guess I need to do it again with different papers and film stock combinations.
Mystery solved. Thanks to all.
Pretty simple, really.
First make sure the unit works...
Check the sensitivity control:
- Place the probe under the enlarger with no negative;
- Set the 5-10-20 switch to 5;
- Turn the sensitivity knob to the max;
- Adjust the aperture and head height so the needle indicates the minimum time on the scale;
- Turn the sensitivity down and see the needle swings freely;
- Repeat for the 10 and 20 switch settings, the sensitivity control will need to be lowered with each change of the switch;
- When switching ranges the needle should indicate the same time on both scales.
To check the the range switch:
- Set the switch to 5, adjust the aperture and sensitivity control so the needle is centered on the '5' scale, raise or lower the enlarger head if needed;
- Close the aperture one stop, the needle should indicate 10 on the '5' scale;
- Turn the switch to 10, make sure the needle points to 10 on the '10' scale;
- Close the aperture 1 stop, make sure the needle indicates 20 on the '10' scale;
- Set the switch to 20, the needle should indicate 20 on the '20 'scale.
To calibrate for a specific paper:
- Make a just-not-white print with no negative - stop the lens down as the time should be around 7 - 15 seconds;
- Place the probe under the enlarger - all safelights need to be off;
- Set the range switch on 10, twiddle the sensitivity knob until the needle points to the time you used to make the print;
- Note the sensitivity knob setting - this is the speed/sensitivity to create a just-not-white tone on that paper;
- If you are out of range then use the 5 or 20 switch/scale;
- If you use VC filters then you should meter with no filter but make the print with a filter.
- You can repeat for any tone you wish. A paper will have a sensitivity setting for every tone it can produce.
- A step tablet can let you find the sensitivity settings for a wide variety of tones with just one print.
- Place the probe where you want your white point to be - or any other tone for which you know the sensitivity setting;
- Set the sensitivity knob appropriately;
- Read the time from the meter, adjusting the 5/10/20 knob to let you use the most readable scale - ie, the needle towards the middle of the range;
- Adjust the aperture up or down if you want more or less printing time.
...and then stumble into bed exhausted without having made one print! Trust me, trying to master this will do nothing for your printing in the long run. The seduction of a "miracle meter" is enticing but ultimately futile. Keep it as a museum piece in a glass cabinet and let your eyes and your test prints be the judge...;)
Thanks for the exhaustive advice Nicholas - but how do you know when you have made a good just not-white-print? Is there an accepted definition? I'll give it a try.
Tony - I may never use it for much, but it's just one of those mysteries I had to solve. LRT. The tapestry that is rich.
Thanks to all for the help.
Not a print, a test strip/test patch/whatever. A just-not-white tone, the first one that is different from the white of the paper. Make the test strip at 10% intervals or so.
Originally Posted by Paul Byrnes
Nicholas, thanks for the clarification. Much obliged. I get it now.