I have a bedside digital clock radio, the numbers are red and glow in the dark, I find that if I am lying in bed on my right hand side and looking at the clock and if I then roll in bed so that the view of the glowing digits from my left eye is progressively reduced by my nose, then the focus of the glowing digits becomes much sharper, and is sharpest just before the view of the numbers is cut off by my nose, so, “Why is it so?”

Guess: reduced aperture gives greater depth of field, hence sharper focus.

Michael V said:

Guess: reduced aperture gives greater depth of field, hence sharper focus.

Michael V, thanks but how is the aperture reduced?

bob(from black rock) said:

Michael V said:

Guess: reduced aperture gives greater depth of field, hence sharper focus.

Michael V, thanks but how is the aperture reduced?

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By shading part of your pupil with your nose.

Michael V said:

bob(from black rock) said:

Michael V said:

Guess: reduced aperture gives greater depth of field, hence sharper focus.

Michael V, thanks but how is the aperture reduced?

.

By shading part of your pupil with your nose.

Yeah, thanks, that’s a pissabolity

the eyes have it

shakes fist at flickr

Michael V said:

Guess: reduced aperture gives greater depth of field, hence sharper focus.

Not sure whether this is the same or similar, but if you have an irregular-shaped cornea/astigmatism, the reduction in pupil size will also reduce visual distortion.

It’s the pinhole effect, if you want to look it up. Remember the pinhole camera? You are reducing the aberrant peripheral rays and retaining the well focussed central rays. You get a sharper but much duller image.

buffy said:

It’s the pinhole effect, if you want to look it up. Remember the pinhole camera? You are reducing the aberrant peripheral rays and retaining the well focussed central rays. You get a sharper but much duller image.

Of course, and I made a pinhole camera out of a chocolate box myself as a kid back in 1955 it worked but not very well, thanks buffy.