The dual grid, Variable Contrast Cold Light head (VCCL), is a great device for your enlarger if you print on black & white VC papers. These heads allow you to dial in any contrast grade your VC paper is capable of producing. You have continuously variable contrast at your fingertips. And, yes they do work. The trouble is, every paper is different. Setting the dial on the head to any random equal setting may or may not produce a grade #2 contrast. Worse yet, what two settings should you choose?
When you start using a new VCCL head you are now faced with a quandary. How do you calibrate this thing so you have some idea what paper grade you are actually getting? Did you know you can calibrate a VCCL head to a known standard? You can know what settings of the blue and green grid will give you an equivalent grade #2, or #3, or anything within the range of the paper!
Yes you can calibrate a VCCL head, and here is how it can be done. Look at the article “USING BTZS TO CALIBRATE YOUR VARIABLE CONTRAST COLD LIGHT HEAD” originally published in the Sep/Oct 2007 issue of View Camera Magazine in the ARTICLES area of our web site.