Mirror Mirror On the Wall

February 11, 2005 8:13 AM

My bathroom has mirrored walls instead of tiles. When I look at myself in one wall/mirror, I seem slightly shorter and wider than I seem in the other mirror, creating the illusion of a 5 lb difference in my appearance. Is there a way to figure out which mirror (if either) is accurate?
posted by xo to home & garden (9 comments total)

Sure. Take a piece of cardboard ohhh, a foot on each side with a hole cut in the center. Take a photograph of the cardboard in each of the mirrors through the hole, as dead-on straight as you can manage. Load the photos in your favorite image editor and measure the cardboard to see which mirror is closest to being right.
posted by kindall at 8:20 AM on February 11, 2005

Possibly you should start by getting a spirit level and seeing whether each wall is flat and at right angles to the floor, an angled mirror could have an effect.

Naturally you should already be convinced that tall and thin are accurate and paper over the other mirror immediately.
posted by biffa at 8:21 AM on February 11, 2005

A bowed (warped) mirror would have exactly that effect. Think funhouse mirrors. Probably, one of the walls had a bow before the mirror was applied to it. Either one wall is bowed up and down, or the other is bowed sideways. Perhaps even both.

Use a straightedge.
posted by mischief at 8:25 AM on February 11, 2005

Have someone else join you in the bathroom.
posted by MrMoonPie at 8:36 AM on February 11, 2005

Answer or Hijack, I'm not sure which...Is it possible that the place you stand when you look at yourself in these mirrors is closer to one mirror than the other? (I'm not suggesting that it's a perspective issue, but the mirror somehow reflects slightly differently at different distances.)

I suggest this because while trying on clothes on day in a large chain store that will go un*cough*Jacob*cough*named, I noticed that I looked great in the mirror hanging on the door of my fitting room, but quite a big larger in the mirror on the wall at the end of the row of fitting rooms. However, as I walked over to the farther mirror I found that the closer I got to the mirror the skinnier I looked. This was noticeable not just to me, but to the person I was shopping with.

I suspect that they might have some those-pants-make-you-look-great mirrors in the fitting rooms, and that these mirrors don't work quite as well at a distance. I don't even know if such a thing is possible, though (this is the hijack part: is that possible?).
posted by duck at 8:44 AM on February 11, 2005

At least one of the two mirrors is curved in one dimension; just take a good straightedge to them and find out which. (It's unlikely that either mirror is curved in more than one dimension, so you probably don't look shorter and wider, just shorter for your width or wider for your height.)
posted by nicwolff at 10:22 AM on February 11, 2005

This is a thread that really needs that Orthagonality fella.

I don't think the photographs-of-cardboard method would work, unless you are using a distortion-free lens. (Odds are you don't have one.)

You may be able to see the distortion by looking at a straightedge reflected in the mirror.
posted by Kirth Gerson at 6:37 PM on February 11, 2005

The photo is likely to have some lens distortions, yeah, but one picture will be out of square, which would be really, really weird for a lens to do.
posted by kindall at 9:18 PM on February 11, 2005

Follow-up: I used a spirit level and the 'wider' mirror was, in fact, outwardly bowed! The 'narrow' mirror was too, but only slightly. A straightedge put up against the mirror did show that it was off in some way, but it was hard to determine how off until I tried the level. Thanks, all. (I will try the camera trick out of curiosity someday when I have time.)
posted by xo at 9:59 PM on February 14, 2005