Shooting Challenge: Spherical Refraction

Illustration for article titled Shooting Challenge: Spherical Refraction

We've all seen reflection used in photography—like when a lake doubles as a mirror to the sky. For this week's Shooting Challenge, we're going a step more complicated and using the principles of refraction.

The Challenge

Photograph anything you'd like that includes some sort of spherical object, like a water drop or ball of glass, that's noticeably refracting a source.


The Method

So wtf is refraction, you ask? It's actually what allows a camera's lens to work.

At its most simple, refraction is the turning or bending of a wave (in this case, a wave of light) as it passes through a medium. In terms of this challenge, that medium will be a sphere of glass or water (or something I haven't thought of to list here).

To actually photograph refraction, you need a sphere (that will most likely be in focus) capturing a world or subject (that will most likely be out of focus). See examples in this excellent flickr collection, but don't let them limit how you push the bounds of the challenge yourself.


Spherical refraction flips an image upside-down (because of the sphere's nature of a biconcave lens, I believe), which is plain neat, but on top of that, getting into the actual physics of what's occurring might lend a hand to creative ideas. UPDATE: From the comments:

The image flips because the sphere, which is acing as a lens, has a negative magnification (m). Optically speaking, the distance between the object and the sphere is considered negative (object distance = z, z0). The equation for the magnification is then m=z/z' (in air) so m < 0. With m < 0 the image is flipped upside down. This of course changes when you add a relay lens to erect the image to rightside up... so two properly spaced lens can produce an erect or right side up image.


The Rules - READ THESE

1. Submissions need to be your own.
2. Photos need to be taken the week of the contest. (No portfolio linking or it spoils the "challenge" part.)
3. Explain, briefly, the equipment, settings, technique and story behind shot.
4. Email submissions to, not me.
5. Include 800px wide image (200KB or less) AND a 2560x1600 sized in email. (The 800px image is the one judged, so feel free to crop/alter the larger image for wallpaper-sized dimensions.)
6. One submission per person.
7. Use the proper SUBJECT line in your email (more info on that below)


Send your best photo by Sunday, July 25th at 11PM Eastern to with "Refraction" in the subject line. Save your files as JPGs, and use a FirstnameLastnameRefraction.jpg (800px wide) and FirstnameLastnameRefractionWallpaper.jpg (2560px wide) naming conventions. Include your shooting summary (camera, lens, ISO, etc) in the body of the email along with a story of the shot in a few sentences. And don't skip this story part because it's often the most enjoyable part for us all beyond the shot itself!

[Lead Image by Shooting Challenge alum Chris Andrews]


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