Since the early days of photography artists were intrigued by this novelty. Many painters used photographs as sources, but for a long while photography was seen as inferior to painting in terms of depiction of real life. There were things that photographs could not do, such as capturing colours or motion. With time, photography came to be considered as an art form in its own right, and it often followed closely new developments in modern art. The exhibition at Tate Modern explores the relationship between photography and abstract art over the last hundred years.
The American photographer, Aaron Siskind commented that painting could be immediately abstract, unlike photography, which had its starting point in the real world and real objects. It was therefore easier for painters to create abstract art. 
It soon became apparent that photography was in fact well-suited to abstraction. Throughout the exhibition photographs are juxtaposed with paintings and sculptures, illustrating how fine arts responded to photography, and how the advances in photography techniques brought new forms of expression.
Shape of light begins with early responses to abstract painting, such as Marta Hoepffner’s photograms which closely resemble some of Kandinsky’s compositions. At a time when abstract art was seen as radical, photography played an important part in the discussion of the status of art. The American photographer Alfred Stieglitz, a life-long promoter of photography as fine art, in 1903 started a journal Camera Work which was devoted to modern art and photography. 
Meanwhile, not everyone agreed on what should and what should not qualify as art, which is nicely illustrated by the story behind one of Brâncuşi’s works (see below). On display is Brâncuşi’s Maiastra (1911), bird-like bronze sculpture set on a limestone base. Maiastra dominates the space with its shiny presence, it looks as it could have been a sculpture of a deity in an ancient temple. Looking at it today we would have no problem identifying it as a piece of art. Right next to it is a photograph taken by Edward Steichen of Brâncuşi’s other work Bird in Space (1926) in a setting which also brings to mind an imaginary ancient temple.
The sculpture on Steichen’s photograph was the subject of a court case in 1927, which questioned its status as art. Steichen bought Bird in Space in 1927 and shipped it to USA. Artworks were exempt from tax in the USA at the time, however the Bird could not qualify as art according to the officials, as it did not imitate a real object, and was therefore classed under the category ‘Kitchen Utensils and Hospital Supplies’. Brâncuşi challenged this decision and won in court, in a way securing the official stamp of approval for abstract art. 
Bauhaus school of art opened in 1919 in Weimar, Germany. It was a pioneering establishment which emphasised the equal status of all arts, such as architecture or photography. One of the influential teachers at the Bauhaus was the Hungarian-born László Moholy-Nagy, who together with his wife Lucia Moholy experimented with photographic techniques, inspiring generations of photographers and artists. In Russia one of key promoters of art photography was Aleksandr Rodchenko. New developments in photography also facilitated experimentation in terms of subjects. Going beyond naturalistic representations, and departing further from the real-life objects, photographers freely explored extreme angles, ‘bird’s eye’ or ‘worm’s eye view’.
Some of the objects in those pictures are still identifiable, others are skilfully transformed beyond recognition into abstract art. Works by Bill Brandt cleverly manipulate human bodies into abstract landscapes.
Many works on display correspond with art movements of the twentieth century such as Surrealism, Action Painting and Op Art (Optical Art). The invention of colour photography and digital photography opened up a whole range of possibilities. Contemporary artists featured in the exhibition continue the legacy of their predecessors, but they also search for new ways of expression merging different media in their artistic practice. The work by Maya Rochat A Rock is A River (2018) seems uninhibited by the exhibition space. Rochat’s installation is an explosion of colour and light bouncing off the walls and doors, and even ‘spilling’ on the floor.
The story of painting with light continues, as the visitors take photographs of the photographs on display. Seeing works that were cutting-edge decades ago can be very humbling in the age of almost unlimited access to cameras. Shape of light offers an opportunity to reflect a little on how we use photography in our daily lives.
 –  Gallery labels, Shape of light exhibition.
More about the exhibition on Tate’s website: https://www.tate.org.uk/whats-on/tate-modern/exhibition/shape-light
Shape of light runs at Tate Modern 2 May – 14 October 2018