The Design of the Visual Field
It was seen in Chapter IV that usually the eye task, that is to say the object we observe carefully during our work and which we want to see in detail, occupies only a small part of our visual field. The details we see sharply are still smaller, they may be one or two words on a printed page looked at from a normal reading distance (40 cm); or that part of a piece of knitting in which we want to count stitches; or the upper part of the body of a violonist standing at a distance of 20 metres on a platform; or that part of the road on which we see a car approaching at 300 metres distance. This part of the eye task is not wider than a solid angle of ± 2°. If, as stated in Chapter IV, the whole eye task which we can see with fixed head and moving eyes is included in a cone of 8° upwards and downwards and 10° to right and left, the part we can see with the greatest precision is only 1/500 to 1/1000th of it. Now it is obvious that since the whole visual field contributes to the total impression we obtain when looking at our work, the whole composition of that visual field has an influence on the way we see things.
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