Get Olympus 7-14mm f/2.8 PRO at B&H Photo.
As compared to a 35mm DSLR, the Olympus 7-14mm f/2.8 PRO is equivalent to a 14-28mm lens in its field of view and f/5.6 in terms of its depth of field.
See also summary overview of the Olympus 7-14mm f/2.8 PRO and the Dana Lake, Dana Glacier, Dana Peak 7mm series.
Aperture Series @ 10mm: Vernal Creek in Dana Meadow (EM5 II, HiRes Mode)
These pages should be mandatory reading for anyone considering this lens.
Shot with the Olympus E-M5 Mark II utilizing high-res sensor shift mode, specifically the about $1199 Olympus OM-D E-M5 Mark II Limited Edition Titanium.
Such vernal streams abound in Yosemite through July or so but usually dry up by August.
Vernal Creek in Dana Meadow
f6.3 @ 1/25 sec, ISO 200; 2015-07-25 19:20:05[low-res image for bot]
E-M5MarkII + OLYMPUS M.7-14mm F2.8 @ 20.8mm equiv (10mm)