Firstly, thanks to Mick Fagan and others who have been helpful answering my questions on working with the Colorstar type machines. After a four hour attempt to calibrate my Colorstar 3000 analyser, Im rather unsure as to how helpful the unit really is; after all, in four hours I could have made a good number of prints from my visually defined filter pack. Through the process of making 6 test strips on Kodak Supra Endura to test for a neutral grey from a grey (Expodisc*) 35mm Kodak Portra 400VC-2 negative. The 3rd strip seemed to give the most accurate result, the enlarger filter pack came to M:102, Y:114 - Meopta Magnifax 4a colour, (although the density was off by perhaps a 1/2 stop); only two units off on the magenta from the 104 magenta / 114 yellow pack I defined without the analysis function. Aside from the issues related to the 400VC negative reference negative; another issue that comes to mind relates to how the light is metered. My Colorstar only came with the diffuser attachment for the light probe, so I used the probe without the attachment for nulling the Colorstar LEDs; this method gave a exposure time of approx. 18 seconds @ f/8 which is correct for my process. However, when a pictorial negative is loaded in the enlarger, using the diffused attachment the density reading goes off, and the filtration pack seems rather arbitrary. The Frances Schultz articles seem to indicate using multiple probe attachments: http://www.xs4all.nl/~colors/info/articles.html If printing without the analysis function is assumed; work prints can made from standard filtration and fine control over colour balance and density can be made after viewing the work prints, which may be more nuanced than using the Colorstar anyway. In conclusion, I may well make another attempt to work to calibrate the Colorstar with newly exposed reference negatives, but Im not sure how helpful the process will be... *The color visible through the viewfinder with the Expodisc 52mm attached changes depending on the lens subject; previously Mick Fagan has suggested an Expodisc reference grey negative is best made near to midday with a clear blue sky.