I think this is related to pupil size. The reason vision is blurry when looking through a lens that doesn’t have the correct refractive power is because the circle of least confusion isn’t positioned on the retina. However, when we look out into a bright sunny day, the pupils constrict and the cone of confusion steepens. This means that there is less divergence the further away you move from the centre of sharp focus. Effectively, the depth of acceptable focus has increased. Here’s an example… When I wear my varifocals indoors, the floor is blurry when viewed through the reading zone, because the focal length is optimised for 30-40cm. However, outside on a bright sunny day, the ground appears much less out of focus through this zone, because my pupils are much smaller and the depth of focus has increased.
I think this is related to pupil size. The reason vision is blurry when looking through a lens that doesn’t have the correct refractive power is because the circle of least confusion isn’t positioned on the retina. However, when we look out into a bright sunny day, the pupils constrict and the cone of confusion steepens. This means that there is less divergence the further away you move from the centre of sharp focus. Effectively, the depth of acceptable focus has increased. Here’s an example… When I wear my varifocals indoors, the floor is blurry when viewed through the reading zone, because the focal length is optimised for 30-40cm. However, outside on a bright sunny day, the ground appears much less out of focus through this zone, because my pupils are much smaller and the depth of focus has increased.