I realized after reading your reply that I should have specified "wide angle scenic lens". I have been in situations out in the Rockies/Wyoming, etc. where, my 500 F4 was my scenic lens of choice, reaching out to isolate some distant scene.
However I am looking for recommendations for a wide angle scenic lens. I attended a Presentation quite a while ago by a regionally well known, well published scenic photographer, and I believe he said that, overall he tended to shoot most of his scenics between 18 and 22 mm (of course that was in the Northeast U.S. with generally shorter line of sight). Given that, and the 1.3X crop that I have on the Mark IV, I would think that going with something like a 24mm would not be wide enough. Obviously I can do a Search and find a listing of wider lenses, but I was hoping for some feedback from people who have used specific lenses and are happy with them.
Thanks very much for your input, it's greatly appreciated.