Several times per year the moon is bright enough and at the right angle to create a night rainbow, a "moonbow", in the mist created by Lower Yosemite Falls. Many people think that this phenomenon can only be seen and photographed from the bridge below the falls. While that is the most common place for people to gather and photograph the moonbows, you can see moonbows in waterfall mist whenever the angles are right, so it can pay off to explore other shooting positions. Even with Lower Yosemite Falls I often find moonbows in the waterfall's mist as I hike in towards the bridge. Give it a try once or twice as you hike in and and as you hike out.
As a starting point for predicting the best times to catch a moonbow in Yosemite, Don Olson of Texas State University has calculated the best times to look for a moonbow from the bridge below Lower Yosemite Falls:
http://uweb.txstate.edu/~do01/
http://uweb.txstate.edu/~do01/
If you go to the bridge to photograph the moonbows, please don't use headlamps, as they throw light uncontrollably all over the other photographers' shots. And red lights are the worst, the most inconsiderate for you to use... very difficult to edit out of shots later. This isn't astronomy, you're not in a darkroom. Please have the simple courtesy to leave the red lights at home. For seeing your camera controls without destroying your night vision, hold your (dimmed) phone display on top of your camera, facing back at yourself. Any light of any kind that you sine back at the front of your camera, to see if there is water on the filter for example, will probably appear in the shot of the people next to you.
You can also catch the North Star directly at the top of Yosemite Falls, with the Big Dipper above. It you have enough patience you can shoot a star trails sequence here, but you'll probably also catch a lot of flashlights and headlamps as people hike in and out. Note that moonbows are most typically seen under a nearly-full moon, so if you simply give your eyes a few minutes to adjust, you probably don't need a headlamp or flashlight to walk in and out on this paved path. You'll probably see much more with night-adjusted vision and no light than you would with poorly adjusted vision and a tiny spot of light. That can even be true under the light of the stars only if you're in an open enough area for the starlight to shine on the ground around you.
I also found a moonbow in Lower Yosemite Falls (click to enlarge) from the Illouette Falls viewpoint and Four Mile Trail trail head a couple of days earlier at midnight. No crowds and foreground-destroying red lights here! There's virtually no limit to where you can shoot Yosemite moonbows from, if you do a little searching.
There were also many reflection opportunities in vernal pools in Cook's Meadow. This pool does not exist or it is too low after winters with too little snow, such as 2014.
I hope that I've provided some useful information on Yosemite's moonbows so you can pursue some interesting and unique shots.
If you'd like to join me in Yosemite sometime, you can find my Yosemite photography workshop schedule on a dedicated page accessible from the top page of this blog (I'm currently working out the dates for 2014, so you might have to check back or get on my mailing list to hear when they're released):
http://www.jeffsullivanphotography.com/blog/yosemite-national-park-photography-workshops/
If you'd like to join me in Yosemite sometime, you can find my Yosemite photography workshop schedule on a dedicated page accessible from the top page of this blog (I'm currently working out the dates for 2014, so you might have to check back or get on my mailing list to hear when they're released):
http://www.jeffsullivanphotography.com/blog/yosemite-national-park-photography-workshops/
