Good analogy. One things I've come to believe over time as well is that it isn't only incorrectly poor results that can come from one of those pieces being off. For instance, it is fairly clear that a subject who is moving isn't going to be as easy to photograph even if the camera and the photographer are good or that a poor photographer might lead to a poor photograph.
However, and others may disagree with me here, I lean toward believing that a photo can be artifically good to a certain extent as well -- photoshopping to use your analogy. A photographer can also create some degree of misrepresentation in his pictures through misuse, accident, an optical illusion, unusual lighting, etc.
I say this not b/c I think that any of us has wrongly ided kids but b/c I've seen a lot more fluctuation on IQ and other ability scores than I had been prone to believe would exist in the past and I've seen kids tested by people who were determined to find giftedness somewhere who found something other testers did not (and I'm a skeptic in some of these situations).
