What lens to use to photograph a full double rainbow

Just before sunset today, a gorgeous double rainbow appeared over the San Francisco bay. I happened to have a fisheye lens attached to my camera, so I ran outside and snapped this shot. The rainbow stuck around for a few minutes, so I had time to shoot using a few different setups.

There are many articles out there with tips about how to photograph rainbows; there’s nothing I can write about technique that hasn’t been covered, but I wanted to show what you can expect to get using a few different wide lenses. What was surprising is that a 16mm lens on a full-frame camera (10mm on APS-C; 8mm on Micro Four Thirds) is not wide enough to capture a full double rainbow. I didn’t have time to try a 12mm or 14mm lens, but I did shoot using a 16mm full-frame fisheye lens on the full-frame Sony a7R II, and a Rokinon 8mm II fisheye lens on a Sony a6500. You’ll notice that an iPhone (or other current smartphone) has no chance of capturing a full rainbow in a single shot, although sweeping a pano works well.