Fernand Khnopff had a keen interest in photography. Although he claimed to know nothing of the technique, it was discovered after his death that he was in possession of sophisticated equipment and technical manuals. Some 40 photo prints were also found in his archive, most of which were used for his own work. These photographs served as preliminary studies and as a stock of memory images.
Khnopff based his pastel drawing (Secret) on a highly staged photograph of his sister, Marguerite, whom he had pose in heavy robes against a background of drapes with peacock feather motifs. What is remarkable about this photograph is that it is technically perfectly executed: the shot is razor sharp and well lit; definitely not the work of an amateur. Did Khnopff take this photo himself, or was he only responsible for directing the picture leaving its technical execution to a professional photographer? In any case, Khnopff has accurately recreated the photograph, albeit now blurrier and mistier. He has turned it into an idealized, symbolist dreamscape.
For the Bruges cityscape, Khnopff probably used photographs by the Antwerp photographer Gustave Hermans. However, by framing them differently, he gave them a mysterious, almost mystical character.