Читать книгу Bird Senses - Graham R. Martin - Страница 43

These functional components of an eye can be matched to the two main functional parts found in all human-made imaging systems. From large astronomical telescopes to the small cameras built into mobile phones, these systems all have one part that produces the image and another that analyses it, and it is clear that the properties of these two components differ greatly.

Even within the cameras of mobile phones properties can be varied to give images that differ markedly in the information they provide. These differences in information capacities result primarily from three fundamental attributes: the degree of detail that can be detected, the extent of the world that is available for analysis, and the range of light levels over which the camera will operate. These will be familiar and important to keen photographers, but even manufacturers of mobile phones draw attention to these features in their marketing materials.

Comparing a mobile phone camera with an astronomical telescope is straightforward. Both are doing essentially the same thing in the same way, but the levels of information they provide are phenomenally different. However, neither one can do the other’s job. The essential point is that the same consideration applies to eyes. They have evolved in different species to provide information for the conduct of different tasks and in different environments. Differences in their eyes are the result of relatively fine-tuning of both image production and image analysis, similar to the fine-tuning of components that underlies differences in phone cameras.

That people are willing to invest time and money in choosing between phone cameras indicates how differences in the information extracted by cameras are functionally significant. That eyes can differ markedly in all of these attributes suggests that if we were able to choose between different types of eyes, rather than having those we are born with, we might spend a lot of time in coming to a decision.