A response to an essay by Gregor Weber on 'Vermeer's pictorial world'

In the catalogue of the 2023 exhibition of the paintings of Johannes Vermeer in Amsterdam, Gregor Weber writes about ‘Vermeer’s pictorial world’ and the question of what tools the artist might have used to obtain his miraculous perspectives.[1] However, there are some basic misconceptions about perspective and optics in Weber’s article that should not go uncorrected, lest they pass into the accepted Vermeer wisdom.​​​​​​

Weber describes three possible tools: mathematical perspective construction; a sighting grid (Alberti’s ‘veil’); and the camera obscura. He needs to decide which is more likely. Vermeer would surely not have used all three. The grid of wires or strings would have been feasible in itself for making drawings. The consequence of its use would be that Vermeer would have had to draw corresponding grids on his canvases. However, very little under drawing of any kind has been detected beneath Vermeer’s paint layers, and certainly no grids.

As for perspective construction, Weber repeats the idea put forward by Jorgen Wadum that Vermeer had a simple method that involved inserting a pin in the canvas at the picture’s central vanishing point, and using a chalked string attached to the pin to mark the images of receding perspective lines.[2] Wadum’s sole evidence for this conjecture is the presence of small holes at these points in a number of pictures - which must indeed indicate that Vermeer put in pins. However, there is no other mention of any such ‘pin and string’ technique in the entire literature of perspective methods, so far as I am aware (and I have read much of it). Wadum was perhaps thinking of the use of chalked strings to mark lines on walls for frescoes, or for constructing theatre sets in perspective. But in those cases, the pins and strings are being used to transfer perspective layouts that have already been set up on paper.

The reason that there is no mention in the literature, is that pins and strings just cannot do the work. They would only allow Vermeer to draw the lines leading to the vanishing point. The central issue in perspective is how to determine the positions of other lines in depth, and how to work out the foreshortening of objects. This is the key problem with which all authentic methods have been concerned since Alberti. A ‘pin and string method’ is the invention of Wadum.

Weber reproduces an illustration from a perspective treatise of Abraham Bosse of 1648 (see the top of this article). Here there are wandering curly lines looking like the loose ends of stretched strings. But Weber has misinterpreted these. Bosse is illustrating the very influential method of geometrical construction introduced by Girard Desargues (made with a ruler and measuring scale), whose distinguishing feature was precisely that it did not start with vanishing points. The positions of these points in a picture were the results of the method. Placing them was not its first step. The curly lines in Bosse’s diagram must be a fanciful and misleading invention of the draughtsman.

Weber has a diagram of the basic perspective structure of ‘Officer and Laughing Girl’ with its central vanishing point and horizon line. He marks the positions of two supposed ‘distance’ points’ on the horizon. In general, this would be done by following the diagonals of the floor tiles, which is impossible in this case because no part of the floor is visible. Instead, Weber has used the lines of the chair on which the soldier sits. These do not however lead to the true distance point at the left. The chair has a vanishing point of its own. This is on the horizon, but in a different place from the distance point.[3]

The officer sits in a type of chair with brass lions’ heads on the back that is seen in several paintings, as for instance ‘The Glass of Wine’. There are real chairs of this type in the collections of the Rijksmuseum and the Prinsenhof in Delft. The figure above sets Vermeer’s version against a photograph of a chair in the Prinsenhof. This is a spectacularly accurate perspective rendering, true to all the shapes and dimensions of the original. How could this image be constructed with a pin and string? How could one even find its two vanishing points since it is set obliquely? One could not begin.

There is the further point that, as with the sighting grid, any real workable perspective method would involve drawing many lines on the canvas, both construction lines and the outlines of objects - and there are almost none to be found.[4]

What is more, neither perspective construction, nor the use of a grid of wires would explain all the evidence of the reproduction by Vermeer of artefacts of lenses that critics and historians have pointed to over the last hundred years.

Weber illustrates a design of small box camera obscura from Johann Zahn’s Oculus Artificialis, first published in 1685. This is well after Vermeer’s death, but there is indeed evidence of box cameras being known in Holland during his lifetime. Weber perhaps imagines Vermeer looking at images of scenes in a camera of this type to study effects of light and shade, and seeing some of the optical effects that he seems to copy in paint. But Weber cannot have tried this for himself.

The image produced by such a box camera, with a lens of say 4 or 5 centimetres in diameter, used indoors, is very faint. (Out of doors it would be brighter and clearer.) There are three reasons. Since the lens is small, not much light is admitted. (Booth or room camera can have much bigger lenses.) Light is lost as it passes through the ground glass screen, and the image is softened. The image is observed under ambient light and seems subjectively much dimmer than the image in a room or booth camera in which the artist is completely enclosed, and his eyes can acclimatise. For clear usable detailed images of his interiors, Vermeer would have had to use a booth camera.

Weber says, correctly, that “not a single camera obscura from Vermeer’s time still exists.” If one did remain, “it would enable us to judge the quality of the projections.” But seventeenth-century lenses of very high quality survive, some made in Delft.[5] There is the evidence of those who saw camera images at that time including Constantijn Huygens, who famously said that “It is impossible to describe for you the beauty of it in words: all painting is dead in comparison, for here is life itself.”[6] I have built booth cameras myself using lenses no better than their seventeenth century counterparts, in which it has been possible to see the “special characteristics of Vermeer’s art that might indicate that he used the instrument.” Weber is very incurious about the evidence available on these questions, and all the experiments and critical analyses relating to Vermeer and the camera made by many art historians and optical specialists.

What would explain Wadum’s pinholes, if a camera was used? Once the main parts of an image are traced, the position of the central vanishing point can be found. The artist wants to get the lines leading to this point exactly straight and uses a ruler. The ruler is rested against the pin.

A cubicle type of camera obscura then is the only practicable type with which Vermeer could have drawn and painted interiors. Weber believes that “Steadman is surely going too far with his thesis [in my book *Vermeer’s Camera *[7] that Vermeer painted with the help of a camera obscura.” Had Weber been willing to entertain this idea however - something that many readers of my book with knowledge of perspective and optics would allow that I have proved definitively - then he would find that this mode of working throws light on many of the questions of method and style discussed throughout the catalogue.

Weber has recently published a book on Johannes Vermeer: Faith, Light and Reflection, revealing for the first time that the camera obscura was a recurring metaphor in the Catholic devotional literature of the period.[8] (And showing by the way how widespread knowledge of the instrument must have been.) Reading my book, Weber would have learned that Vermeer’s booth camera is reflected at the very centre of the image of the mirrored ball in ‘Allegory of the Faith’. It is a pity that he was not able to bring his and my findings together.