Some Historical Background
Fern Ledge is no doubt one of the most famous of the not-famous spots in Yosemite. That is to say, it is rarely if ever visited by casual tourists and even visitors who know the park well only go occasionally, yet aficionados of Ansel Adams' photography have likely seen pictures taken from there and readers of John Muir have no doubt read stories of his exploits there. Back before the Yosemite Falls Trail was built, the quickest way out of the north side of the Valley was up Indian Creek (that's the major canyon right of Yosemite Falls as you look towards the rim) and the best way to see the falls themselves was to hoof it up to Fern Ledge. Since 2007, when a University of Texas team began publishing a calendar of best times to see them, there has been a growing interest in the Yosemite Falls moonbows, or lunar spraybows that one sees at the full moon. For John Muir, however, "The best point from which to observe them is on Fern Ledge" (The Wild Muir: Twenty-Two of John Muir's Greatest Adventures, p. 50). He goes on to say:
A wild scene, but not a safe one, is made by the moon as it appears through the edge of Yosemite Fall when one is behind it. Once, after enjoying the night-song of the waters and watching the formation of the colored bow as the moon came round the domes and sent her beams into the wild uproar, I ventured out on the narrow bench that extends back of the fall from Fern Ledge and began to admire the dim-veiled grandeur of the view. […] and wishing to look at the moon through the meshes of the denser portions of the fall, I ventured to creep farther behind it while it was gently wind-swayed, without taking sufficient thought about the consequences of its swaying back to its natural position after the wind-pressure should be removed. The effect was enchanting. […] I was in fairyland between the dark wall and the wild throng of illumined waters, but suffered sudden disenchantment […]. Down came a dash of spent comets, thin and harmless looking in the distance, but they felt desperately solid and stony when they struck my shoulders, like a mixture of choking spray and big hailstones. […] The heavier masses seemed to strike like cobblestones, and there was a confused noise of many waters about my ears — hissing and gurgling, clashing sounds that were not heard as music. […] Somewhat nerve-shaken, drenched and benumbed, I made out to build a fire, warmed myself, ran home, reached my cabin before daylight, got an hour or two of sleep, and awoke sound and comfortable, better, not worse, for my hard midnight bath (The Wild Muir: Twenty-Two of John Muir's Greatest Adventures, p. 51-52).
Not content with almost dying that once on Fern Ledge, Muir later staged his investigations of the Yosemite Fall ice cone from there. The ice cone builds all winter from the freezing spray and the falling ice, reaching a height of a few hundred feet. Once during a windstorm, Muir ran up to Fern Ledge, not having learned his lesson the first time. On his first attempt to look into the cone, he was "almost suffocated by the drenching, gusty spray," but ever the adventurer, he waited for the wind to blow the fall to the west and than ran out on Fern Ledge for a look.
Since Muir's day, with the creation of the Yosemite Falls Trail, Fern Ledge has become a relatively less-visited place (though in absolute terms it perhaps sees more visitors than ever). The most famous post-Muir visitor is certainly Ansel Adams who captured images looking up Yosemite Falls from Fern Ledge on at least a few occasions, in both color and black and white (you can see his image, not to mention buy the 8x10 print for a mere $235, at the Ansel Adams Gallery). I'll give you an 8x10 print of one of my images for a lot less. Ansel Adams' picture is almost like seeing the waterfall for yourself. My picture is almost like seeing Ansel Adams picture for yourself. The low-res version I have on the web, is almost like seeing my picture for yourself. All in all, you're better off just to go there.
Getting started can be a bit difficult (we lost faith and cut up too early). Basically, you want to get to the Park Service stables (Lower Yosemite Fall, NOT the concessionaire stables by Curry Village). If you don't know where they are, the easiest way to explain it is to say that you take the Lower Falls loop, starting on the village side (rather than the Lodge side), though it doesn't make that much difference. You'll be passing the park service housing on your right, at the end of which the trail turns to the right. Stay on that trail until you pass the first and the second turnoff for the stables and keep going until you're at the bottom of the big open talus field, with a very distinctive square boulder in it.
Head up the talus field staying to the left (west) until it enters the forest. Eventually a creek bed, usually dry, breaks off from the main talus field. You'll want to find the trail on the right side (east) and follow it until you get to the base of the lower cliff band. From there, you start climbing and make a tight step around a corner, cross the creek bed that you were in earlier and begin the long, gently-rising traverse across Sunnyside Bench. There is a packed out trail, and please stick to it. Veering from the trail is both potentially dangerous and will cause extra impact on these excellent meadows of flowers. The soil is loose, dry and easily disturbed and a few footprints can cause serious damage. If you see a great flower and want to get closer, keep walking — these are not rare species and eventually you'll see the same ones within inches of the trail. Furthermore, some of these dirt slopes are virtually at the angle of repose and the trail tends to cut up away from the edge a bit (it takes a middle line between the edge of the cliffs and the difficult terrain on your uphill side).
The meadows along here have some of the better flower displays in Yosemite Valley, with Live Forevers, Larkspur, Paintbrushes, Harvest Brodieia and many more. Like I say, be nice to them and stay on the trail.
Walk pretty much to the end of Sunnyside Bench. There is a way to get up to the next level by just walking up a series of ramps, but the easiest way to find is one that is about 100 feet from the end of Sunnyside Bench that makes a short scramble (about 30-40 feet) up through some oak trees. You can tell you're on the right track because you will see branches that have been cleanly cut with a saw and, eventually will see cairns.
Wind your way up the slopes and slabs above, heading generally toward the left (west) side of Lost Arrow spire. The trail here is the same one that climbers use to approach Lost Arrow Chimney, Freestone and Yosemite Point Buttress (though many climbers will choose a more direct start and will veer off to their climbs before the end). This section of the trail can have amazing displays of Giant Red Paintbrushes and bright red Live Forevers growing in some of the most improbable places.
When you get within a quarter mile or so of Fern Ledge proper, you should have a pretty good general idea of where you want to go. Follow your eyes and your ears until you emerge at Fern Ledge to the thunderous applause of Yosemite Falls heralding your success. Basically, you want to get slightly above Fern Ledge and then angle down and out to get to it. How far out you can safely go depends on the season, but don't forget Muir's account. Before reading Muir, I had already started called the rushes of water that break from the main fall "comets". I was delighted to find that he saw the same thing in those fiery balls of water. I haven't been as close as Muir, but I can honestly say that it isn't really better farther out the ledge. It's cool to get out far enough to replicate Ansel Adams' picture, but the real pleasure of Fern Ledge is to lie on your back for hours chatting with a friend, mesmerized by the falling comets of water. It's hard to describe, but it is enchanting, meditative, mesmerizing and if not for the sun beating on you telling you to go find some shade, you could lose yourself there for hours.