A cosmic marble
A few days ago I went for a stroll to the flea market in Barrio Lastarria, one of my favourite neighbourhoods in Santiago. I stumbled upon this one stand selling all sorts of used artifacts, among which there were a bunch of crystal balls, and I couldn’t help buying one. For just a few bucks, this may very well have become my new favourite “lens”!
A few days later I went up to Paranal Observatory for an observing shift, and I decided to test the crystal ball as an astrophotography lens. I placed it on the handrails of one of the entrance corridors to the Paranal residencia, and put my tripod and camera below it, at an angle such that the Milky Way was visible through the ball.
Then I chose which lens to attach to the camera. The focal length doesn’t change what you see within the ball, but it does affect the background behind it. So I picked a 24 mm lens to get a large enough view of the Milky Way as a backdrop.
Once I nailed the focus on the stars within the ball, I had to decide which aperture to use, and after a few attempts I chose f/4. Smaller f-numbers yielded a too shallow depth of field: the edge of the ball was too blurry, and the bokeh of the background stars was too large, making it hard to discern the Milky Way. Larger f-numbers allowed very little light through, and also made the bokeh in the background smaller than I wanted.
I hope you like the final image! If you have the chance to buy one of these cheap crystal balls, I totally recommend it. They’re really fun to use, and they can add a very original spin to your photography. I already have a few crazy ideas in mind for future images. Stay tuned!
Canon 6D + Rokinon 24mm f/4, 30 sec, ISO6400