When not wearing my glasses, why is nothing distant in a photo blurry, but distant things in a mirror are blurry?
In: Physics
Light from the photo is all close and at the same distance from your eye. Light in the mirror is reflected from different distances from your eye
A photo is a 2dimensional thing. Those things are fixed in focus because that’s what the camera recorded. Has nothing to do with your eyesight. You just have to focus on the image. The image is already in focus for you.
The mirror is a more complex physics question I don’t totally understand. To do with reletive distance and light.
Ultimately I think it’s because it is a reflection of what you would normally see so if you would normally need glasses to see it, you’ll still need them because reletive to you, the light travels the same distance to reach your eye. But I can’t say for sure
Hen looking at a photograph, the light merely travels from the paper to your eyes. In an optical sense, image is at the paper.
In a mirror, the light must travel from the original object to your eye. Certainly, it changes direction at the mirror, but that is not its source.
when looking at a photograph, light has to travel from the photograph to your eye, and that’s it.
when looking at a distant object in a mirror, even if the mirror is very close to you, light has to travel from the object to the mirror, and then from the mirror to your eye.
So say you have a mirror 30cm from your face, and you’re looking at something that’s 1m behind the mirror, the light will have to travel 130cm total.
(OBJECT) ———70cm——— (YOU) –30cm– (MIRROR)
Whereas, if you snapped a picture of the mirror in the same setting, and hung it on the mirror, all the light would have to do is to travel from the picture to your eye (30cm)
(YOU) –30cm– (PICTURE)
Let’s say you’re looking at a distance object that’s in focus through your phone’s camera but looking directly at the object you see it blurry.
You can think of the phone camera as doing some of the work that your glasses would have because the light only travels from the screen to you but looking directly the light has to travel all the way from the object to you.
Something about mirrors, even if you are close to a mirror the light still has to travel a long distance (from the object to the mirror then to you). This isn’t the case with a camera because a camera has a bunch of lenses inside it that bend the light like your glasses.
What’s important for your vision isn’t the distance but the angle of the light rays to each other (going past eli5) but the angle is directly related to the distance unless it passes through something which bends the light such as a lense in which case there’s no meaningfull relationship until you account for the lense.
I’m guessing you suffer from short sightedness, where your eyes can’t focus to infinity.
A photograph is a two dimensional recording of light intensity made out of silver crystals or pixels taken through it’s own lens set to the correct focus, so your eyes are focusing on a piece of paper or glass, it simply travels directly into your eye.
Mirrors reflect light back, exactly the same as what went into it, so if a mirror was reflecting a scene of a distant landscape, focusing onto that scene with short sightedness will be an attempt to focus your eyes to infinity, which as you may know its not possible with that condition.
With a mirror your looking at real light, whereas a photograph is just a state of light in time stored on a flat surface.
You can try this with a camera, focusing on the mirror will get the surface of the mirror, any longer and it will be what the mirror is reflecting
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