Danish architect Sophus Frandsen created the Fibonacci light, his timeless classic for Fog & Mørup, in the early 1960s. Despite being one of the company’s most expensive lights – the various versions costing from 10 pounds six shillings to 17 pounds seven shillings in the UK in 1963, when the average weekly wage was 20 pounds 16 shillings – it remained in production until F&M’s demise in the early 1980s. The light was awarded the gold medal at the Leipzig Messe in 1967 and was selected for inclusion in the show Die gute Industriform at the 1968 Hannover Messe.

Danish lighting designer Henrik Clausen presents a fascinating video profile of Sophus Frandsen at the Fagerhult Lighting Academy, which we have transcribed here:

"'I hope that I am not going to tell you anything here today that you don’t already know!' The person who said these words expected a lot from his audience. But at the same time he stepped down from the pedestal just by saying these words. For of course we all knew that we were listening to a real master in understanding light, lighting and lighting design. [Shows picture of Frandsen.] Here you see the person who made a big difference in my life. The picture is taken at Sophus Frandsen’s 80th birthday. He has become a living legend in the Danish lighting community. He had a lifelong position teaching light, lighting and lighting design at the Royal Danish Academy of Fine Arts in Copenhagen. I attended his lectures 25 years ago. He taught us about perspectives, and illustrated them with ancient Chinese arts. He showed that we feel less distance between mountains when the artist puts down cloud and mist. The clouds give a soft and diffuse light, and the artist often uses a cool and blueish light to create the feeling of distance. Nature clearly teaches us the same thing. The further away an object is, the more soft and blueish the light gets, and the mist or the low-hanging clouds diffuse and taint the light. It creates depth and perspective.
"Sophus often brought this old 6×6 light projector along. The light source is of course incandescent. Sophus would never use anything other than that, because he insisted on perfect colour rendering. Before he projected anything he made us watch the empty screen only showing a huge white square. Then he got out his slides. But his frames didn’t hold any beautiful pictures. They held all sorts of samples of clear glass used for window glazing – samples from all over the world made in different countries from different moulds. Glass is not just glass. Even clear glass changes the colour of the light. We looked at all kinds of different samples, sitting there watching the big square on the screen turn from white to soft blueish to green, and then you suddenly understood that light had to be treated with respect. And that’s exactly what Sophus did.
"When Sophus worked, there were no such things as lighting designers. Lighting was an integral part of architecture. Nevertheless, Sophus was a true lighting designer – but most of all, he taught us all how to see. And for that I am forever grateful."

Clausen’s presentation provides an interesting context for the instruction in a late 1970s Fog & Mørup catalogue to fit clear (rather than opalescent) bulbs in Frandsen’s Fibonacci. The catalogue says: 

"The Fibonacci is a lamp where the designer has done much work around the screening of the bulb, and the result is almost complete anti-dazzling in all directions. Fibonacci can therefore be suspended high or low as one prefers without dazzling, at the same time giving an even, diffuse illumination of the room. The light, airy design makes it suitable in almost any interior and for any style. For the Fibonacci lamp only clear bulbs should be used, as anti-dazzling and the right distribution of light can only be obtained with the correct bulb. The lampholder is adjustable to the various bulb sizes, so that the distance to the shades can always be correct."