OK a bit off topic this one, but could not figure which forum to post in, my 11 yeard old is into conventional art and I was thinking of buying him a camera lucida as a drawing aid, has anyone used one of these as I do not want to waste £50 if they are not very good.

My friend’s daughter was tryingto use something that looked very similar to that.

The problem was the subject had to have VERY bright lighting, and her drawing pad had to be in very dim light to see anything.
She borrowed a couple of photofloods and stands from me, but the projected image was still very dim.
Along with the lighting requirements, she also found not being able to move her pad around freely as she draws, very confining and gave up using the device out of frustration.

That was about five years ago, so maybe the one you are looking at is better designed (brighter mirror, etc.).

Ask in the 2D forum, as they are very knowledgeable when it comes to traditional art and could give you better advice.
 

 From wikipedia as i was intrigued about what one was which might help (taking on board SWAMP's experiences of the scene not being light enough):

"If white paper is used with the camera lucida, the superimposition of the paper with the scene tends to wash out the scene, making it difficult to view. When working with a camera lucida it is often beneficial to use black paper and to draw with a white pencil."