Thanks for your fast response and your explanation.
I understand that you suggest keeping things simple and calibrating my monitor to 6500K. I also understand what you said about the flexibility of human eyes.
Nevertheless, my ultimate aim is to produce quality prints - though I am a simple amateur without any ‘threat’ of having my pictures published in a nice book … Anyway, I would like to compare my prints to my on-screen photos, so I intend to keep the rules of using a 5000K monitor in a “real darkroom” and a Color Master 1 from Just-Normlicht to check and compare my prints.
Regardless of whether calibrating my monitor to 5000K or 6500K, my original question remained unanswered … For me at this moment the real question is not which particular colour temperature (5000K, 6500K, or any other colour temperature) is worth using for processing a photo. The real question is whether there is any software in the market, which is capable of generating such new versions of TIFF and/or JPEG files the colours of which are automatically modified as if the images had been processed on a monitor with a different colour temperature. In other words, if I process a photo on a monitor calibrated to 5000K and save the resulting TIFF or JPEG file, it would be great to have an application that is able to convert this image into another file, opening of which on a 6500K monitor would show the same colours as my monitor (calibrated to 5000K).
I understand that the perception of colours highly depends on the ambient lighting conditions. In an ideal world we would know exactly under which conditions our photos will be looked at by other, and our image processing monitor would be calibrated accordingly.
I also understand that the actual colour temperature of my monitor does not have a direct impact on the printer. However, there is an obvious and crucial indirect impact: I make modifications of the image on the basis of what I can see on the monitor … And my percention of colours changes with changing the colour temperature of my monitor.