# fuzzy objects in mirror **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [April 21, 2007, 8:49pm UTC](https://boards.straightdope.com/t/fuzzy-objects-in-mirror/401105 "2007-04-21T20:49:24Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Brendan\_Mullany](https://avatars.discourse-cdn.com/v4/letter/b/8edcca/32.png) [@Brendan\_Mullany](https://boards.straightdope.com/u/Brendan_Mullany)\ **Post date:** [April 21, 2007, 8:49pm UTC](https://boards.straightdope.com/t/fuzzy-objects-in-mirror/401105/1 "2007-04-21T20:49:24Z")
while I was learning photography in High School, I noticed that if you look through a manual focus camera into a mirror, the focal distance is TWICE the actual distance to the subject. In other words, hold the camera 6" away and the focus on the camera itself. Then, read the distance scale on the lens. It reads 1 foot at 12". I have no idea why this is ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [April 21, 2007, 9:47pm UTC](https://boards.straightdope.com/t/fuzzy-objects-in-mirror/401105/2 "2007-04-21T21:47:19Z")
[QUOTE=Brendan Mullany] while I was learning photography in High School, I noticed that if you look through a manual focus camera into a mirror, the focal distance is TWICE the actual distance to the subject. In other words, hold the camera 6" away and the focus on the camera itself. Then, read the distance scale on the lens. It reads 1 foot at 12". I have no idea why this is [/QUOTE] I assume one of the mods will be by presently to put your posting in the proper place (General Questions, I assume). In the meantime, WHY are you surprised that you are focusing at 12"? The total length the light is travelling is 12". The fact that the mirror changes the light’s direction is irrelevant. ---
**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\ **Post date:** [April 21, 2007, 10:05pm UTC](https://boards.straightdope.com/t/fuzzy-objects-in-mirror/401105/3 "2007-04-21T22:05:26Z")
Welcome to the SDMB, Brendan. I presume this is in response to Cecil’s column [Why does a mirror image look fuzzy to a nearsighted person, even if the mirror is close?](http://www.straightdope.com/classics/a3_349b.html) For future reference, please note that a link to the column you’re commenting on is appreciated. ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [April 21, 2007, 11:43pm UTC](https://boards.straightdope.com/t/fuzzy-objects-in-mirror/401105/4 "2007-04-21T23:43:14Z")
[QUOTE=bibliophage] Welcome to the SDMB, Brendan. I presume this is in response to Cecil’s column [Why does a mirror image look fuzzy to a nearsighted person, even if the mirror is close?](http://www.straightdope.com/classics/a3_349b.html) For future reference, please note that a link to the column you’re commenting on is appreciated. [/QUOTE] Oops! Didn’t realize that this did relate to a Cecil’s column (so I guess it is in the right place). Sorry 'bout that. My comments stand though - it’s the total distance the light travels that matters. ---
**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:** [April 23, 2007, 2:56pm UTC](https://boards.straightdope.com/t/fuzzy-objects-in-mirror/401105/5 "2007-04-23T14:56:16Z")
Not the question asked, but it came to mind when I read this – Polaroid used to make cameras that focused using a sort of sonar sensor. Of course, if you were banking your shot off a mirror the focus would be off, because the sensor would gauge the distance to the mirror, not to the object being photographed. The samr thing happened if you were looking through a window. Of course, you’d end up with really in-focus shots of the mirror or window.