The other day I mentioned accuracy in drawing and how important this technical ability is for creating convincing pictures. Often guidebooks mention that the secret to art is being able to see things as they are, in an almost child-like manner, instead of how you believe them to be. However I'm starting to convince myself that this isn't the limiting factor - instead it's whether or not you can make your hand accurately describe the shapes and contours which you're seeing.
For example this is my attempt to draw a relatively straightforward arrangement of cans. All that's needed here are some straight lines and a few ellipses; nothing fancy. And yet, in practice, my shapes appear weirdly wrong and unreal. Partly this is because I've fallen back into the habit of twisting end surfaces to make them flatter for the viewer but even without this the ends of the cans aren't convincingly attached to the body:
This is very obvious when a photo of the arrangement is turned into a line drawing and the contours stand out. Here there's distortion from the top of the central can being closer and the left-hand can top is a suitably flattened ellipse in shape. So working harder on my ellipses is a key task if I'm to achieve a drawing like this:
