The real voyage of discovery is not seeking new landscapes, but having new eyes. (Proust)
Nikon 24mm f3.5 ED PC-E. Whenever the high tech, always ON world of cell phones, tweets, Facebook, and digital photography magic begin to wear on me, I fantasize about digging out the 4x5 large format camera and retreating to a simpler time. In a view camera there is no autofocus. Instead, there is a careful, iterative process of adjusting the lens until you have achieved perfect clarity. (This for an image that is upside-down.) Only then would the film carrier slide into the camera, the cover be pulled back, and the shutter release cable be triggered. It is photography at its most deliberate and zen.
The 24mm PC-E lens is as close to this as you can get in a digital world. (Unless you mortgage the farm and get a digital back for the view camera...) It has the capacity to move in two planes--vertical and horizontal--and assure that not only you avoid those converging lines in architectural photography, but that everything is in sharp focus in a landscape. This bit of magic is connived by moving the lens so that the plane of exposure (film) and light reaching the sensor (digital) is parallel to the focal plane of the scene you are photographing. You don't hurry with this lens. It is not for photojournalism or sports photographers. PC-E, btw, stands for Perspective Control - Extra-low dispersion. The lens has low dispersion glass, three aspherical elements, and a rounded, nine-blade diaphragm that will actually produce reasonable bokeh, just in case you want to do the opposite of everything-in-focus. It is a lens with superb sharpness edge to edge, and great color rendition.
It's tempting to think of it as special, to leave it at home and venture out with what seems a more utilitarian zoom--the 24-70 (no-where near as sharp at 24mm.) or the 14-24. (Heavy, and with a bulbous, unprotected front element, vulnerable--and also not quite as sharp at 24mm) Besides, the 24 PC-E is fussy. Maybe even delicate. It is a totally manual lens. Manual focus. Manual adjustments. And woe be the consequence of it being adjusted wrong, or slipping from its setting when you shoot. Stuffing it into a pack that will be jounced around for days seems the wrong thing to do.
But the lense is well-built, and far sturdier than first impressions might suggest. The rewards of taking it for long hikes are great. For landscapes, especially geological images where you want to have those forground rocks as well as the background mountain sharp, the 24 PC-E is unrivaled. Send it packing!