worldcycle Loc: Stateline, Nevada

I live at Tahoe, go to Yosemite often. Wide as possible my recommendation. Take a tele of some sort because you will see bears both places.

amfoto1 Loc: San Jose, Calif. USA

I believe you use a Canon 80D, which is an APS-C crop sensor camera (many of the responses pertain to full frame).

For Yosemite with a crop sensor DSLR I'd recommend an EF-S 10-22mm f/3.5-4.5 USM or similar.... great for scenic shots. The Canon EF-S 10-18mm IS STM is a smaller, lighter less expensive alternative... more plasticky, but quite capable. There are also some similar 3rd party lenses, but most fall a bit short of the potential for these two Canon EF-S ultrawides.

Personally I would also take my EF 100-400mm II telephoto, even though it's about 3.5 lb... great for wildlife. There's not much likelihood of seeing larger wildlife in Yosemite unless you trek into some of the more remote areas. But in the busier areas there are likely small wildlife, birds, etc. that are relatively accustomed to people. I use an EF 1.4X II on this lens occasionally, too.

As an alternative, one of the EF 70-300mm can serve well in place of the 100-400mm. The 70-300mm is considerably smaller and lighter, but cannot be used with a 1.4X teleconverter.

I also like to carry a macro lens, just in case. My favorite is the Canon EF 100mm, but when I want to travel light I've been carrying a Tamron 60mm f/2 that's very good, quite compact, and doubles nicely for the occasional candid portrait shot. A "crop only" lens (like the ultrawides mentioned above) this lens' f/2 aperture is a stop more than most macro lenses offer, isn't typically needed for macro (usually stopping down in search of a little more depth of field), but is what makes a true dual purpose lens.