On 2010 Jan 4, at 2:53 AM, Graeme Gill wrote: > Every instrument needs regular factory calibration if it is to retain > its traceability to official standards (assuming it has any to begin > with - many cheap instruments don't). It really depends on how important > this aspect is to you though. For photography, how often would you personally have an i1 Pro calibrated? I called Greytag Macbeth when mine was officially a few months past its due date, and the guy who answered the phone told me that, unless I was experiencing problems, I might as well save my money. That was some time ago, but I'm still not having any problems with it that *I* can spot.... b&