Why can a camera only focus on one distance at a time, and what occurs inside to change that focal distance? Does the same principle apply to our eyes?
In: Physics
A typical camera lens is hard and inflexible. So there is only one distance at which it can focus light. Your eye has a crystalline lens that is soft and jelly-like. There are cables attached to that lens, which when they loosen, allow the lens to achieve a more spherical shape which allows it to change focus from distance to near. The lens becomes harder over time, so the loosening of the cables have less of an effect. The lens is not as easily able to attain this spherical shape anymore – this occurs gradually and typically people notice the effect around the age of 40. Usually around this time (or 45 or 50), people need to start wearing reading glasses to help change the focus up close.
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