ambience is even more critical. This is because rays of sun entering from the east, west and south change shape and direction during the day. A complex scene would be very difficult to paint while the shadows and reflections move. Furthermore, accurately depicting harsh light requires a large dynamic range (difference in darkness between blacks and whites) which most traditional paints can not reproduce. Italian Renaissance painter Leon Battista Alberti alluded to this lack of dynamic range in 1435, writing that “no surface should be made so white that you cannot make it [...] whiter still”. However, it was Leonardo da Vinci who first wrote about studio lighting in detail. By 1492 he had discovered the adaptation of the human pupil to darkness, noting that “the eye perceives and recognises the objects with greater intensity [when] the pupil is more widely dilated”. Following this, he painted in a dimly lit studio and avoided harsh southern light. The effects of this soft, dim lighting can be seen in later works such as the Mona Lisa. The use of specifically northern, rather than merely dim light became more common during the Dutch Golden Age with painters such as Rembrandt and Johannes Vermeer. This can be seen in works such as Vermeer's The Milkmaid. Artists without access to north facing windows have developed alternative solutions to replicate some of the desirable properties of north light for painting. These include: Diffusing direct sunlight (usually from the south) by adding opaque covers to windows. These covers can be sheets, blinds or even tracing or baking paper, however, they have the potential to affect the light's colour if they are tinted off-white. This may or may not be a desirable effect depending on the artist. Painting early or late in the day. While this may add warmth if done close to sunrise or sunset, it allows for diffuse and dim light to be obtained from a south facing window. Using artificial lighting such as a daylight lamp or continuous, daylight-balanced studio light. Softboxes can be added to improve diffusion. Artificial lights can be expensive, but allow for greater versatility, as several of them can be arranged to fill in certain shadows and create more customised lighting. This is important when trying to recreate Rembrandt lighting or in fine art reproduction. However, due to the inverse square law, light falling on an object close to its source