Published on 1 January, 2003

The painter David Hockney has garnered quite a bit of attention lately by saying that renowned artists from the past often used optical aids to help make their art. Camera obscura, camera lucida and convex mirrors were all employed, says Hockney to enhance the beauty and verisimilitude of many old master pictures. Hockney has written a big, lavishly illustrated book, Secret Knowledge, aimed at proving his case and I have now read this book as well as another book with a similar point of view called, Vermeer's Camera. I have diligently examined the graphs, weighed the arguments, studied the pictures, and after due consideration I now feel absolutely confident in saying that this whole point of view from its initial conception to its elaborate proofs is, in a word, kooky. And by that I don't mean just slightly kooky. I mean seriously Bigfoot fanatic, U.F.O. convention, world class kooky. Hockney's argument breaks down into seven major points:

1. The line in a Warhol drawing resembles a line in an Ingres drawing. Warhol projected his images onto the paper, Ingres must have too.
2. The detail work in Ingres paintings is so complicated and so elaborate that it could only be produced by projecting and tracing.
3. Art got dramatically more lifelike during the same era that lenses started to develop.
4. The perspective in certain paintings is too difficult for someone to do freehand.
5. Paintings of people drinking with their left hand show that a camera obscura (which reverses images) was used.
6. The dramatic light and shadow of chiarascuro paintings resembles sunlight more than studio light and sunlight is what's needed to get a clear image when using a camera obscura.
7. Certain distortions in some paintings look like the kind of distortions that would be caused by optics.

That's it. Those are the arguments. To my mind what's not there is more striking than what is. I feel its significant that what we don't find on this list is; "This great artist was often (or even once) seen using a special lens" or "This great artist was known to own a camera obscura," or "when I posed for this artist he was often looking through a prism device." Hockney says that over this whole span of art history the reason we don't have any independent verification of such use is that optical aids were a closely guarded secret. I'll say. Four hundred years of world famous artists peering through things, climbing into dark boxes, and tracing images upside down and nobody mentions it? No model, no client, no apprentice utters a word? Clearly we are in grassy knoll territory. Let's go through the list:

Number one.

Warhol's line looks like Ingres' line, therefore... This is an easy one. Warhol's line does not look like Ingres line. Warhol's line is stark and unvarying, Ingres' line is subtle, changing, shifting from sharp to soft, defined to vague and back again. Unlike Warhol's, Ingres line is expressive of the substance that is being depicted; skin, cloth, bone, etc. Its the kind of line used by an empathetic draughtsman (as opposed to an outline tracer) who is looking sensitively at his subject.

Number two.

The detail work in Ingres patterned cloth is so complicated and so accurate that it could only be done with mechanical assistance, specifically, a camera obscura, Hockney says. To prove his point, Hockney compares Ingres cloth with some patterned cloth painted by Cézanne.The Cézanne cloth was "most certainly eyeballed," says Hockney, and, "consequently," it looks strikingly less convincing than the Ingres.This is one of those missing parts arguments; detailed accuracy can only be achieved with a camera obscura. Ingres painted with detailed accuracy, therefore he used a camera obscura. Hockney has skipped the part where he proves that detailed accuracy can only be done with a camera obscura.In fact, if you need to paint a lot of detail a camera obscura is the last thing you'd want to use. Here's why.

The camera obscura requires complete darkness. The viewer needs to be inside a very dark space and its into this space that light from a pinhole projects itself. Ingres, therefore, would have to be working in more or less a pitch black chamber. He wouldn't be able to paint in there. He couldn't see. All he could do, and Hockney agrees with this, is draw the outline of the projected image onto a canvas, an outline that he would presumably fill in with paint after he'd gotten out. Its a lot of trouble just to get an outline, but even if we grant that Ingres might be willing to go through all of this, there's still a big problem. Namely, the camera obscura reverses the image and flips it upside down. The upside down part is not a problem as Ingres could trace the outline onto his canvas and then turn the canvas right side up afterwards. But the reversal, as far as I can see, puts the kabosh on the whole project. How can it be helpful to have your subject outlined on your canvas in mirror image? Once the outline is in place, then you would have to paint in the colors from life, looking directly at your subject, but everything on your canvas would be backwards. Hockney never really spells out this difficulty, but it seems to me to be an insurmountable one. Who would want to try and paint on a drawing that's the reverse of what they're looking at? Complicated detail is hard enough, but backward complicated detail?

Rather than let this reversal phenomenon undermine his thesis, however, Hockney, in proof number six uses it as evidence that artists worked with the camera obscura (a proof I'll get to later). The reversal is a difficulty though, and Hockney tries to counter it by demonstrating that a certain kind of convex mirror set up could re-project the image in a non-reversed way. But this solution is also problematic because the image you get is at most only twelve inches square. Here, a less dedicated theorist might conclude that this device would only be relevant for tiny paintings. The indefatigable Hockney, however, proposes that those using the convex mirror rig could piece large paintings together out of truncated little snippets. The artist, inside his dark box would, says Hockney, copy the projected image of a part of the subject onto the canvas, move the viewing opening to a new position, copy some more, move the opening, etc., until the whole image was hobbled together like a collage. Does Hockney seriously think that going to all this trouble would be faster or easier (or more accurate) than painting directly from life?

Getting back to the Cézanne comparison, I think the fact that Cézanne's cloth doesn't look as convincing as Ingres' has everything to do with Cézanne's painting skills and nothing to do with mechanical assistance. Beautiful fine work has been done from life for centuries without any assistance whatever, but perhaps anticipating this line of reasoning, Hockney moves on to his next point.

Number three.

Art got dramatically more lifelike at the same time that lenses were developed. Because Ingres is not the only painter who did fine detail, art history is filled with such skillful people, Hockney now must drag herds of previously innocent old masters into his mechanical aid plot. He points out that as the renaissance flowers and painting geniuses start to emerge, lens technology is also developing. This is congruency being confused with causality. It is similar to saying, there was a full moon when I got the flu, therefore, the flu is caused by a full moon. Its simply bad logic. Lenses were indeed being investigated during and after the renaissance, just as many other discoveries were being made. That is what the renaissance was all about. Still, Hockney has no evidence that artists used these lenses. He shows us pictures from before the renaissance that look flat, and then pictures from after the renaissance which have depth. This demonstrates that lenses were used, says Hockney. More accurately, this demonstrates that there was a renaissance. This is what happened during the renaissance as artists made discoveries about visual observation and paint and beauty. Artists figured out how to get the convincing illusion of depth onto their canvasses and, as a matter of fact, depth is exactly what you don't get working from project images. The pre-renaissance artists' work looks flat because they are copying surface effects. The great artists who follow are thinking more like sculptors, building visual depth onto their canvasses. Using lenses to copy would undermine that sensibility. Tracing outlines, which is what lens use is all about, leads directly back to pre-renaissance flatness.

Number four.

The complex foreshortening of certain subjects is too difficult for perspective alone. The artists must have used lenses. As an example, Hockney shows us a lute painted by Caravaggio and skeptically asks, "Could Caravaggio really have used Dürer's method (perspective analysis) to paint that incredibly foreshortened lute?" The answer is yes. The more complicated the view of the subject, the more you need to utilize perspective. That's why the discovery of the laws of perspective was so significant. These laws allowed the artist to analyze complex objects from complex viewpoints, and render them completely accurately. Hockney shows us various objects seen at difficult angles and says they would be too hard to depict with just perspective, but foreshortened and receding forms are exactly the kind of things that "just perspective" would solve. Trying to get them to look right by tracing them, which is what Hockney's lens method would accomplish, would make the depiction less convincing because it wouldn't be derived from understanding.

Number five.

Paintings with left-handed drinkers in them illustrate the use of camera obscura because people don't typically drink from their left hand. As I said earlier, the reversal effect of camera obscura should, realistically, rule it out as a painting aid, but here Hockney attempts to turn lemon into lemonade. He uses the reversal to buttress his case. He shows us a painting by Carravagio wherein a youth is holding a glass in his left hand. Hockney flips the image to show us that it looks more natural in the right. Putting aside the slander factor against those who are left handed, the picture as Carravagio painted it, requires that the glass remain just where it is. As great painters were once aware, paintings read from left to right. The eye moves across the painting in a rightward motion and it is essential to keep the strongest visual elements on the right side of the image. The glass functions as a coda for the painting, a kind of climax, and if reversed the picture, in a sense, is over before it has begun.

Number six.

The dramatic light and shadow of chiarascuro paintings resembles more than studio light and sunlight is what is needed to a clear image when using lens devices and mirrors. Hockney states, "With the exception of direct sunlight, you don't get such a strong light naturally, certainly not in scenes that are inside apparently darkened rooms like these; but you need such strong lights to use optics." This is another lemon to lemonade situation. Hockney should be throwing in the towel at this point having confessed that sunlight is necessary for the equipment to work, but he surges forward undaunted saying that this explains why we have so many high contrast pictures. In fact, the fact that optics need strong sunlight proves that optics weren't used by the old masters and it does so for the following reasons:

1. The depicted light in paintings by Carravagio, Ingres, Vermeer , etc. is indisputably cool light (as from north facing windows or skylights) not sunlight.
2. Painters avoid indoor direct sunlight because it is too transitory. When it comes in a window, it is constantly moving across the room as the earth rotates, and is illuminating from the same direction for a few moments at the most.
3. Artists for centuries have prized north light studios specifically because they do not receive direct sunlight, and
4. If artists from northern Europe depended on sunlight to paint their paintings, then museums would be empty.

Number seven.

Certain paintings' distortions and drawing errors are the kind of that would occur with lens use. Hockney here is disregarding that earlier business about how the only explanation for the lack of error and distortion in so many early paintings is the use of lenses. Now, all that is put aside so he can say that error and distortion are caused by lenses? I really don't think he can have it both ways. Either lenses help or they don't. And as if this contradictory argument weren't misleading enough, Hockney also, I'm sorry to say, cheats on the accompanying illustration. After a careful study of one of the book's pictures, I discovered a clear case of evidence fudging. To illustrate an example of lens caused distortion, Hockney offers a picture which he claims has two vanishing points where there should be just one. He says that the artist "probably painted the front first, and then, because of depth of field problems refocused his lens before painting the back, hence a second vanishing point." Aside from the fact that again this whole line of argument contradicts his earlier position, what he says is in the painting actually isn't. I took my straight edge and double checked the receding patterns of the rug, and there is only one vanishing point. Hockney's overlaid lines distort the actual lines of the rug's pattern. This is a distortion that is in the service of a completely contradictory and meaningless line of argument.

This isn't the only instance of a picture not representing what Hockney claims it does. On pages 81 and 82 there is a two page spread of a carefully painted chandelier from Van Eyck's Arnolfini Wedding that Hockney cites as evidence of the use of optics. He says, "Notice how the chandelier is seen from head on, not from below as one would expect. This is the effect that you would expect with a mirror lens, which must be level with the objects you would want to draw or paint." What? Now aside from all the other complications associated with drawing with lenses, the objects have to be at eye level for the lenses to work? Hockney keeps sneaking in restrictive information about these visual aids that make them seem less and less useful. But that is not the biggest issue related to this illustration. There is another problem here which suggests that Hockney is assuming that no one would ever actually look at the evidence he's presenting, namely, the chandelier is not at eye level. He presents the chandelier as evidence that a mirror lens was used because it is "seen head on (not from below as you would expect)." But it is not. The upward curve of the center piece and the higher level of the near candles show us that this chandelier is most definitely seen from below. This means, according to Hockney, it could not have been painted using a lens.

I think that when a theory can be completely discredited solely on the basis of its own evidence, we can safely say the theory is very flawed — no good. Hockney's big idea, that the old masters used optics to help them out, is propped up with fuzzy thinking, skewed logic, faulty premises, unwarranted conclusions, and as we've seen, downright dishonesty. If it had been put together by a scientist rather than an artist, we'd have a scandal on our hands. But Hockney is being given a free pass, and his whole cockamamie notion is being swallowed whole by artists and art historians alike. Why? Why are so many people willing to assume that the great artists of the past copied their pictures from projections? Some may feel that Hockney, being a lauded artist himself, know of what he speaks. Others may feel that even if he's wrong about occasional details, there must be something to it all or there wouldn't be all this fuss. But my suspicion is that it meets a need. The giants of art history painted pictures that raised the bar of what is possible and on some level maybe that poses a threat. Great art is inspiring but it can also be diminishing. Hockney's theory pulls everyone down to the same comfortable level.

As for the Vermeer book, which also attempts to prove the use of optic assistance, it is no less cockamamie than Hockney's but the nuttiness is buried under an awe inspiring amount of scholarly commotion. I don't think I've ever seen a book about art filled with so many graphs and models and grids. The author even assembles miniature three dimensional reconstructions of Vermeer's paintings which he then reproduces and draws perspective lines all over to show us that ... well I couldn't tell exactly what it showed us except that the author is not afraid of hard work. Ultimately though, despite it all, I could find no convincing evidence anywhere in this book that Vermeer ever used the camera obscura. In fact, like Hockney, we are helpfully provided with strong evidence that he did not. We are told, for example, that in X-rays of these paintings there are no indications that Vermeer made preliminary outlines. As stated earlier, outlines are all you can do when you're using a camera obscura because its too dark to paint. Thanks to this X-ray information, therefore, we now have a good indicator that Vermeer did not use the camera obscura. The author also generously points out another flaw in his theory. He tells us that conservators have discovered that six Vermeer paintings each have tiny little puncture marks on their vanishing points. This indicates, we are told, that Vermeer used some kind of pin to mark the spot where the paintings' perspective lines converge. Why did Vermeer need to mark his vanishing points? If the author's theory is true that Vermeer used the camera obscura to outline all the subject matter, why would he then need a perspective aid like a marked vanishing point? The author speculates that Vermeer, after he had emerged from his camera obscura, might need to supplement some of his outlines with lines based on a vanishing point. The only reason for a vanishing point is to make sure that all the receding forms in the picture are on the correct diagonals. Does it really make sense for someone to go through all the trouble of working with the camera obscura (no light, reversal effect, etc.) if the diagonals later have to be adjusted? Is this really a process any sensible artist would ever want to go through? Doesn't it seem much more reasonable that Vermeer painted the way Vermeer depicts an artist painting? In his picture, The Allegory of Art, we see an artist in his studio. This painter is not looking through lenses, or crouching in a dark box. He's simply painting from the model, not using any outlines, but painting directly on his canvas. Can we not assume this is how Vermeer painted? Here, within this picture, we are fortunate to have a great artist showing us, in effect, how he worked. Why doubt or complicate it? Why assume Vermeer was being deceitful? Or to put it another way, why be kooky?

Acknowledgements

Gregg Kreutz is an artist and teacher. He teaches oil painting and drawing at the Art Students League of New York in Manhattan and at workshops throughout the United States and France. He is represented by galleries in New York City, Madison, Wisconsin, Chicago, and Austin, Texas. Kreutz is the subject of two instructional videos produced by Signilar Art Videos. For more information, write: Gregg Kreutz, Dept. AA, 41 Union Square, Room 1109, New York, NY 10003.