Photo Tips for Yosemite Moonbows: A Photographic How-To Guide

One of the things I love most about photography is that it entices me to venture out into the world and see wonders I would never otherwise experience.  For example…have you every heard of a ‘moonbow’?  Well, I hadn’t either until a few weeks ago.   I was doing some research for a trip to Yosemite when I saw a mention about moonbows and it caught my attention.  It turns out that a moonbow (also known as a lunar rainbow,  white rainbow or space rainbow) is a rainbow created by full moon at night (instead of direct sunlight during the day).  Although recorded by observers from Aristotle to Benjamin Franklin, they are still not well known due to their rarity.   Not every waterfall can host a moonbow, in fact, the list of well-known locations is pretty small: Yosemite, Victoria Falls in Africa, Hawaii’s Waimea  Falls and Cumberland Falls in Kentucky.   The five required conditions are:

1. Correct “rainbow geometry” when the moon lines up correctly with a waterfall’s mist
2. A clear sky (few, if any clouds),
3. Abundant mist at the base of the fall,
4. An absence of artificial light,
5. Bright, direct moonlight (full or nearly full moon)

So how do you know if there is “correct rainbow geometry?” Well, that was a problem for years.  Although back in the 1870s, famed naturalist John Muir was singing the wonders of Yosemite’s “elusive, ethereal moonbow”, no one could predict when you would be able to see one.  It wasn’t until 2007 that astrometers in Texas figured it out and published a schedule of future moonbow dates.  So there is no guessing anymore, a quick click onto the Texas State University website and you are good to go. Note:  don’t confuse the Texas State University with the University of Texas (which is a mistake I made when I first wrote this blog)…my thanks to William Cardwell for pointing out my error…Go Bobcats!)

Well, by the time I finished reading all this, I was very interested.  When I checked the Texas website and saw that one of the predicted moonbows would occur while I was at Yosemite, I was EXCITED!  All I needed now was a bit more luck… a clear night.  Did my luck hold?   Check out the shot below:

Looks just like a regular rainbow…right?  Whoops, not quite…check out those stars!   To be honest, it doesn’t quite look like this to the naked eye (this is a 30 second exposure).  In person, a moonbow has very subdued colors .   It really depends on the cone color receptors in your eyes, if yours are sensitive, you will see colors, if not, you will see more of a greyish-white ‘bow.’  Either way, it was everything John Muir promised.  In fact, even though it was wet and freezing, each time the moon hit the mist just right, the moonbow would shiver into sight and you could hear the assembled photographers gasp and call out to one another in amazement.  And that’s saying a lot, because my experience is that landscape photographers have a tendency to be quiet and reserved…but you would have never known it that night.

Personally, I was so enthralled that I stayed at the falls for nearly three hours the first night, and nearly as long the next.  I’ll tell you, it is really nice to be able to feel that same sense of wonder that you experienced as a child.  Perhaps it doesn’t happen as often, but I think the emotion is deeper felt than when I was younger.

Tips for my fellow Photographers:

1. Where to Photograph From

   • There are usually at least two locations that the moonbow is visible from:
     1. Lower Yosemite Falls:  The bridge and terrace at the base of the falls (see map below)
        • There is parking available on Northside Drive, just east of Yosemite Falls Lodge.
        • Plan on a short 10-15 minute stroll on the paved trail.  Just follow the signs to ‘Lower Yosemite Falls.’  When you come to a 50 foot bridge at the base of the fall, you have found the spot.
        • The concrete terrace just to the west of the footbridge is the favorite location of most photographers because the bridge can shake a bit when folks walk on it and the terrace tends to get hit with less mist
        • At the terrace, move as close to the north end as you can (closest to the falls).  There is a large fallen log that borders the edge of the terrace, if you can get right up to it, I think you will have the best seat in the house. This location is ‘up close and personal.’  The view, sound and mist are incredible.
     2. Upper Yosemite Falls
        • You can see a different perspective of the moonbow from the parking lot at Sentinel Bridge or just south from Cook’s Meadow
        • It won’t be as crowded but frankly, this view just doesn’t excite me nearly as much as the terrace at the lower falls.

2. When to Go

   • Check the Texas Website and see when moonbows are predicted.
   • The water flow is usually best in the spring which should generate more mist, which should result in a better moonbow.  That isn’t a sure thing, but if you had a choice of when to go, choose the predicted dates earliest in the year.
   • The best tripod locations fill up early, so I’d get there about an hour before the start of the predicted moonbow
   • When the moonbow first appears, it will be high on the falls.  As the night progresses, the bow will move lower and lower toward the base of the falls.  Many viewers think earlier views are the best

3. What to Wear

   • You will likely get wet photographing from the terrace/bridge at the Lower Falls.  Bring good Gore-Tex raingear (preferably something with a hood)
     • If your camera isn’t weather sealed, you will want to have something to cover it with.  You can find everything from cheap plastic covers to high-end Think Tank Hydrophobias easily on Amazon.
     • If you get wet, you will likely get cold unless you have a good jacket under your raingear.  I was dry but freezing my first night because I had thought a forecast of 60 degrees Fahrenheit didn’t require anything warm under my raingear….I was wrong.
     • Thin fleece gloves will make the experience more comfortable as well

4. Bring a Headlamp

   • A headlamp will keep light on your subject while keeping your hands free
   • If your headlamp has a ‘red light’ feature, it will help preserve your night vision
   • Please be careful not to shine your light into the eyes and cameras of your fellow photographers.

5. Tripod/Remote Shutter Release/Extra Batteries

   • You will be taking long exposures and will need a tripod.  And, if you have a tripod with an extending center column, then bring it.  I had my full sized tripod with me and by raising the center column to its full height, I was able to photograph OVER the heads of photographers who had got there before me and staked out the best locations.
   • A remote shutter release will ensure that no vibration will ruin your shot.
   • You will be taking a lot of shots over a couple hours and if it is cold, your batteries will drain quicker than normal.

6. Lens suggestions

   • Bring the widest, fastest lens you have.
   • On a full frame camera  you will need about 28mm to get the entire falls in the frame (about 42mm on a cropped APS-C sensor camera).
   • A 2.8f or faster lens is ideal but you can still get good shots with slower lenses…you will just need longer exposures.

     

7. Lens Cleaning/Drying Cloths

   • Bring LOTS of these.  I found that I had to dry my lens after EVERY shot.

8. Focus on Infinity

   • Getting good focus at night can be a challenge.  Autofocus will not be your friend, so use Manual Focus.
   • If your camera has a Live-View feature, use it
   • Check your LCD after every shot to make sure you have the focus tack-sharp
   • Be careful that you don’t mess up your focus when you are cleaning the lens.  I made this mistake a couple times before I could figure out why my focus kept changing!

9. ISO/Shutter Speed

   • There is a trade-off decision you will have to make between these two settings.
   • If your shutter speed is over 30 seconds, the stars will no longer show as pinpoints…they will start to streak
   • Higher ISO settings will let you use shorter shutter speeds, but will result in higher noise levels
   • With a Nikon 800E and a f/2.8 lens, I was able to shoot at ISOs between 140-200 at 30 seconds with fine results.  Experiment with your camera/lens combination and see what works.  Fortunately, the moonbows often last for a couple hours, so you have time for some trial and error.
   • Use your histogram to confirm that you got a good exposure.
   • Even with a histogram, I’d suggest that you bracket your shots to ensure that you do get shots with perfect exposure.

10. Okay, I’m all set…but where is that darned Moonbow?

    • Remember, the skies need to be pretty clear for a good moonbow, even if you are there on the right night.  If it is a bit cloudy, stick it out and with a bit of luck, the moon will peek thru the clouds before your ‘window’ is over,
    • After you spot the moonbow once, you will know what to look for.  Remember, the colors won’t be vivid to your eye, but the ‘rainbow’ shape will still be there…look for it.
    • See if you can find your head’s shadow and then draw a line between it and the base of the falls…the moonbow should form a 42 degree arc above that line.
    • Even if you still can’t see it, I’ll bet that when the moonbow appears, the folks around you will start pointing at it…that should help!

So, there you have it.  A new potential adventure for you to try and certainly one that will be long remembered.  In fact, often my ‘non-photographic’ friends only pay ‘polite’ attention to me when I drone on about my photo shoots, but when I started talking about moonbows, I think they were truly interested;)

Remember, photography is about a lot more than just pretty pictures!
Jeff

 Photo Tips for Yosemite Moonbows:  A Photographic How-To Guide

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