# Questions about mirrors **URL:** \ **Category:** Factual Questions\ **Created:** [October 4, 2005, 10:10pm UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795 "2005-10-04T22:10:56Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [October 6, 2005, 1:22am UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/21 "2005-10-06T01:22:56Z")
> [@Mangetout](#): > > But the fact remains that the light reaching your eyes, enabling you to see yourself in a mirror is traversing a total path of 10 metres in doing so. And the whole 10 meters is contained within the 5 meter envelope over which your eyes are assumed to be receptive to photons. ---
**Author:** ![snailboy](https://avatars.discourse-cdn.com/v4/letter/s/97f17d/32.png) [@snailboy](https://boards.straightdope.com/u/snailboy)\ **Post date:** [October 6, 2005, 1:38am UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/22 "2005-10-06T01:38:34Z")
Let’s make a more precise condition. If you were near-sighted so that objects over 5 meters were suddenly blurred (I don’t think near-sightedness kicks in so suddenly, but play along here) and you stood 5 meters from a mirror, your image would appear blurry. You could clearly make out any spots on the mirror and the edge of the mirror itself, but the reflection of yourself will be 10 meters away as far as your eyes can tell. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 6, 2005, 1:39am UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/23 "2005-10-06T01:39:27Z")
> [@David Simmons](#): > > And the whole 10 meters is contained within the 5 meter envelope over which your eyes are assumed to be receptive to photons. Oh, I see; you’ve read the question as implying that there is a 5 metre sphere centred on the viewer, in which photons are able to exist. I understand now. Silly to argue about it any further, as the premise itself is so nonsensical. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [October 6, 2005, 1:51am UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/24 "2005-10-06T01:51:27Z")
> [@Mangetout](#): > > Oh, I see; you’ve read the question as implying that there is a 5 metre sphere centred on the viewer, in which photons are able to exist. I understand now. Silly to argue about it any further, as the premise itself is so nonsensical. I somehow knew we were talking about different things (I will **not** repeat **not** say “apples” and “oranges.”) The OP admitted that the premise was unreal but asked, like the maker of a movie or play, that we suspend judgement for just a little while. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 6, 2005, 1:55am UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/25 "2005-10-06T01:55:00Z")
Even so, I’m still not sure that the OP would see the image (in his imaginary scenario; since he’s specifically saying that his vision cuts out images that are more than 5 metres away; the image in the mirror is ten metres away, even though the mirror itself isn’t. Most of this confusion arises from a poorly-defined scenario. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [October 6, 2005, 3:42am UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/26 "2005-10-06T03:42:44Z")
> [@Mangetout](#): > > Even so, I’m still not sure that the OP would see the image (in his imaginary scenario; since he’s specifically saying that his vision cuts out images that are more than 5 metres away; the image in the mirror is ten metres away, even though the mirror itself isn’t. Most of this confusion arises from a poorly-defined scenario. Since we can’t perform the experiment I guess we’ll never know. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [October 6, 2005, 5:15am UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/27 "2005-10-06T05:15:22Z")
> [@Chronos](#): > > If you’re standing 5 meters away from a mirror, **incidentally** , your image … I was reflecting on this statement, but then, rather than focusing on it further, I realized your ideas about the topic mirrored mine rather well and that any disagreement between us was more virtual than real, and likely resulted from trivial differences having been magnified. ---
**Author:** ![smamurai](https://avatars.discourse-cdn.com/v4/letter/s/bbce88/32.png) [@smamurai](https://boards.straightdope.com/u/smamurai)\ **Post date:** [October 6, 2005, 1:29pm UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/28 "2005-10-06T13:29:29Z")
> [@snailboy](#): > > Let’s make a more precise condition. If you were near-sighted so that objects over 5 meters were suddenly blurred (I don’t think near-sightedness kicks in so suddenly, but play along here) and you stood 5 meters from a mirror, your image would appear blurry. You could clearly make out any spots on the mirror and the edge of the mirror itself, but the reflection of yourself will be 10 meters away as far as your eyes can tell. That sums it up. I was originally going to say that my vision blurred past 5 metres but then technically, I would still be able to _see_ the image although not focussed so I decided to make it that my sight cut out completely. > [@](#): > > What if I was looking at an image 5 metres away through a periscope where the angled mirrors were a metre apart, would I see it? In this scenario would I see an image 6 metres away or would the 1st mirror double the image to make 10 then pick up another metre (or perhaps 2?) on the way to the 2nd angled mirror where maybe the 2nd angle would double up again giving me 22 metres? Does the distance in the enclosed tube even register? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 6, 2005, 2:00pm UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/29 "2005-10-06T14:00:07Z")
The distance of an image you see in the mirror, or an array of mirrors - such as a periscope - is the sum of the distances that the light travels on its way to you via the mirrors; the way your eyes perceive and focus this image is no different than if you were just looking at the object at the same distance in a straight line; mirrors just fold the path of the rays, but they still work as if they were not folded, in every way. The path of light between the object and the observer in [these three examples](http://www.gurman.co.uk/Stuff/mirror.pmg) is the same; the object will appear to be the same distance in all three examples, it will require your eye to focus in the same way in all three examples. It really isn’t complicated. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 6, 2005, 2:01pm UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/30 "2005-10-06T14:01:09Z")
[fixed link](http://www.gurman.co.uk/Stuff/mirror.png) ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 6, 2005, 5:08pm UTC](https://boards.straightdope.com/t/questions-about-mirrors/324795/31 "2005-10-06T17:08:05Z")
Damned right the distance inside the closed tube registers. The kinds of “periscopes” you people are discussing are the kind that people use for looking over others’ heads at parades, and in children’s toys. They’re just combinations of mirrors in a box or tube. If there was nothing else, then for a long piece of tube you’d see a teent dot of light at the end, and that’s it – the same as if you look through a long piece of pipe. The kinds of periscopes used in submarines and the like (And in museums, and outside the Edmund Scientific building) actually are more complex. They not only bend the light around the corners with mirrors, they also keep re-imaging the view through a series of imaging and field lenses, so that it seems as if your eye is right up there at the top of the tube. The barrel of a periscope tube isn’t wempty – it’s packed with optical components. [Previous page](https://boards.straightdope.com/t/questions-about-mirrors/324795.md?page=1)