Most photographers who are also printers (either desktop or chemical) know the importance of judging prints under conditions with standardized colour temperature and light levels. For many judging a colour print means holding it under a quartz halogen lamp or possibly also walking over to a window to see how it looks in daylight.

During late 2000 and early 2001 I found myself doing a great deal of portfolio-sale printing using theEpson 2000P, an archival printer which uses pigment-based inks. While these prints are rated to have a 200 year life before noticeable fading, making them the longest lived colour print process available, they occasionally suffer from a problem calledmetamerism. This causes some images, on some papers to display with different colour characteristics under incandescent bulbs and under daylight.

My work-room has large windows, and walking back and forth between my desk, with its quartz-halogen illumination, and the window is no hardship. But when wor...