POTD: Reflecting on Self

Reflecting on Self
Bozeman, Montana

On occasion I will take some time and photograph the crows and ravens that come to feed on bread chunks etc. placed out for them in this hanging feeder on our balcony. For various reasons (e.g. convenience, laziness, desire for warmth) I will set up my camera inside the house and photograph through the double pane window. This is not an ideal situation for clarity and other reasons, one of which I found out when I just happened to photograph when the lighting, both inside and outside the house, was just right (or wrong).

It took me a bit to figure out how, given the configuration I set up, I managed to get an overlapping partial double image of this crow.  The key of course is that this was a double pane window. Looking through a single pane of glass, you can often see your own reflection on the surface of the glass itself, again if the light is coming from the right (or wrong) angle–another reason why you shouldn’t photograph through a closed window in the first place if you’re looking for the best results. In this case the double pane window just compounded the simple reflection issue. I believe the light coming off the crow came in through the outer glass pane and mostly through the inner pane, entering the camera lens as expected. But it was also partially reflected back from the outside facing surface of the inside glass pane, never getting through to the camera; instead bouncing back towards the crow itself.

When that light reflected back towards the crow hit the inside facing surface of the outside glass pane, some of that light passed through the glass out towards the crow, but some also reflected back through the inside glass pane into the camera lens. (Are you confused yet?) If there had only been one pane of glass, the light from the crow would have still reflected off the outside surface of the glass, but not been further reflected back through the window into the camera. (For you sticklers for detail out there, I have to point that there there would actually be an ignorable amount of light that would have been reflected back off the crow itself). Also, the reason you don’t see a total reflected image of the the crow, instead just the part that overlapped the crow itself, is because the background around the crow was too light for the reflection to show up even though it is actually there. And finally I believe that this whole issue was compounded to a degree because the window was comprised of low-e glass, which is designed to reflect light of certain frequencies, mostly in the UV range, but inadvertently affecting the visible spectrum to a degree as well I imagine.

If the physics of this image was obvious to you without all the commentary, my apologies for the long explanation. The same applies if your reaction to all this is “who cares.” But, personally, besides providing me with an entertaining light and optics puzzle, it did result in a kind of interesting image as well I think. I probably should have named it “Double Take” because that’s what I did when I first saw it and it is of course a double taken image.


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