Part 3: How Should I View My Photographs
When we are judging how well our printed photographs match the monitor under what light do we view the photographs? It would be no good viewing them under a red light for example as we would only see the red in the photo and all the other colours would look a bit strange. Even viewing them under a cheap fluorescent tube may give an incorrect idea of what the colours are. There are international standards covering the light that should be used for the accurate viewing of photographs and other art works, for example ISO 3664:2009. This standard mandates the use of a precisely defined spectrum of illumination, the standard CIE illuminant D50. D50 illumination has a colour temperature of about 5000 degrees kelvin although this is not the most important factor. D50 illumination must have a light spectrum that closely matches natural sunlight and the degree to which a light source matches the D50 standard (natural sunlight) is given by the Colour Rendering Index or CRI. To indicate how well a light source matches natural sunlight the source is given a CRI score between one and one hundred. If a light source has a CRI score above 95 then it is a good match to natural sunlight and so meets the D50 criteria.
So if you are comparing a print to your monitor you should view the print under lighting that closely matches the D50 standard. There are a number of bulbs/fluorescent tubes that meet this standard , including Solux halogen bulbs and fluorescent tubes by Vita-Lite. The best Solux bulbs for daylight viewing of photographs is the SoLux BB18003, 4700k, 36 degree, 12v halogen bulbs. These have a colour rendering index (CRI) of at least 99 out of 100. These have a limited lighting angle ie 36 degrees and so a number are required if you want even lighting throughout a larger room. The Vita-Lite fluorescent tubes are also very good and are available in a series of sizes.
John Doody Photography Training