This waterfall can be seen (well, almost) from a turnout on Little River Road between Cades Cove and Sugarlands Visitor Center. The view is partially obstructed by trees in the summertime; otherwise the view is good from the creekside.
I consider this to be an average waterfall and the ratings show it.
The good part of this waterfall is that a hike is not required. However, if you want a close-up view you will have to wade across the Little River.
Traveling westward from Sugarlands, Mannis Branch Falls is about a mile past the turn for Elkmont. Located on Little River Road, the turnout will be on your left. It isn't much, just some dirt parking mainly for fishermen. The right location could be tricky to spot. It would be best to have a GPSr and program in the location.
No hike. My pictures were all taken from the edge of the creek as I wasn't prepared for wading. The location was maybe 100 feet from the parking area.
Lighting conditions were good when I was there with a slight overcast. You can see that I messed up and had a high ISO setting on my Canon. Fortunately the consequences weren't that severe since the waterfall isn't that spectacular and I'm not going to have large prints made.
Obviously you will need a good tripod to get an exposure of any significant length.
Focal length - I would recommend both a wide angle and telephoto lens. You will want the wide angle to get the whole waterfall and creek area, such as the panorama shot at the bottom of the page, but you will need a 200-300 mm lens to isolate the main waterfall in the distance.
I would also recommend the use of a polarizer to cut down on reflections. You will need to correct the color cast of the polarizer either with a warming filter or with post processing with a program like Photoshop.
I didn't play with composition much other than to stitch some photos together for the pano shot below. The creek area and tree coverage limit your options.
Here you go.
Waterfall-Picture-Guide › Tennessee Waterfalls › Mannis Branch Falls