Photography - Nikon AF-S 300mm f4
The Nikon 70-300mmVR is a great hiking lens, but does have it's limitations (namely, speed and sharpness at 300mm). There aren't many affordable options in the 300mm+ range, and the affordable zooms all have compromises. The 300mm f4 is well regarded by other Nikon owners, and now I know why!
The 300mm f4 is super sharp, and there's virtually no difference, regardless of aperture. I basically keep the aperture at f/4, unless I need the extra depth of field, without worry. When the TC17EII is attached, there is a noticeable hit to sharpness, but results are quite acceptable and can still be cropped with success (see the goldfinch image below).
Focusing is super fast. Accuracy with static subjects is perfect. Birds in flight are some of the toughest, and the focusing 300mm f4 makes for a substantially higher keeper rate, compared to the 70-300VR. Accuracy, with a fast moving target, is good under the circumstances. When the TC17EII is attached, there is a noticeable hit in auto focus performance. @500mm, the lens needs good light, and fast moving birds in flight are difficult, at best. Also of note, this lens focuses remarkably close - making it almost macro-like - and is great for close ups.
Compared to my other lenses, the 300mm f4 is a big, heavy beast. Compared to other options (like the 300mm f/2.8), the lens is a dream to carry around. There are reports that the footing isn't great, but I think that would only be an issue with really slow shutter speeds - I've yet to have a problem, though I mostly handhold the lens. I do find it can be a little much to walk around with, hanging from your neck; I also worry the weight may be to much for the mount to bear, so I do not let the camera hang around my neck with this lens attached.
Here are a few samples I have taken with this lens: