Please Note: I intend to keep things as simple as possible here. If there are enough requests to go into more detail about some of the items in the article below that are in Bold Type then another blog may follow this one. (WWW below means What Went Wrong!)
When we look at a photograph that is a bit “blurred” the usual response is to say, ‘Oh, it’s out of focus.’ Then we put it down to experience and probably decide not to get too close to the subject next time. After all modern cameras, digital or camera-phones etc, are so full of automatic features that we expect the pictures we take to be sharp and correctly exposed for most lighting conditions. Subjects much further away than about one metre are usually in focus. In most situations the camera can cope because the focal length of the lens fitted is quite short, say around 8mm to 25mm, and the depth of field in this case will be very wide. Depth of field is the distance between the nearest and farthest camera subjects which can be brought into acceptable focus in the camera, i.e. where there once would have been a film, called the film plane. However, depth of field does not depend only on the focal length of the lens, but also upon the aperture and the distance of the subject. (It also depends upon something called the circle of confusion but I don’t intend discussing that here!).
The aperture of the camera is a little bit like the pupil of your eye, the black hole in the centre of your iris. It opens up and closes down according to whether the light is bright or dim. Automatic cameras can detect the brightness, like your eyes, and adjust the aperture size. A bigger depth of field occurs when the camera aperture is very small and when the subject is at a distance from the camera. So we can more or less guarantee a “nice sharp photo” when the light is bright (camera selects a small aperture) and the subject is say over two metres away - Right? Well, No – not always, because there’s one more thing that produces blurred pictures and it has nothing to do with focussing the lens! It’s the shutter speed.
What Went Wrong ie WWW is followed by a brief explanation in the picture captions. So WWR will be What Went Right!
I know it's better that the animals are not kept in cages, but where there is a breeding programme to assist the re-introduction of endangered species, perhaps we can allow it? It can be educational for children as well of course.