we have high definition for only about the width of your thumb at arms length, so we have to shift our eyes around a lot to get the whole picture.
average refocus 3 times a second.
Physiological nystagmus: the eye tremors when fixated,1 degree, probably to get the image on fresh cones, probably only visible in tight close ups, basically dirty curves keeping the eye alive.
During fixation there is sometimes a slow drifting that's auto corrected by microsaccades
It takes about 100-300 milliseconds (ms) to initiate a saccade. That is, from the time a stimulus is presented until the eye starts moving takes 0.1 to 0.3 seconds, or between 2 to 7 frames (a common mistake is to have the animated character react immediately — on the same frame — to a visual input).
A saccade takes another 30-120 ms to complete, depending on, among other things, the visual angle traversed. That means the typical saccade takes from 1 to 3 frames.
Basically, you can reserve 1-frame saccades for very small movements, 2-3 frame saccades the rest of the time, and very rarely use a 4-frame saccade for a large, deliberate eye movement.
Saccades are a jump with the mind blanking out between, so there is often a quick readjustment after the jump because the target was missed slightly.
Eye input is turned off during a jump, and also about 1 frame before the jump.
So processing of the retinal image takes place mainly between the saccades, during the fixations. These fixations last for about 200-600 ms (5-15 frames), with 300 ms (7-8 frames) being average, during scanning behavior
one of Kevin's tricks to avoid too much eye movement is to hit the jump, and then put a tiny drift continuing it (settleing basically) which will not be seen if the head is moving but will keep the eyes from feeling dead, and from feeling to flighty.
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