Nikon Reflex-Nikkor 500mm f8 hand grip The Kenko 20mm extension tube

The Kenko 20mm extension tube provides substantial macro function with almost any lens (although it's best with lenses 50mm and up)

Interior dimensions are approximately 10x14x14cm

and very slight moisture damage on the rear cover

some very light barrel speckles which appear to be a pretty tenacious paint

we can't vouch for the durability of the finish

Nikon Reflex-Nikkor 500mm f8 hand grip The Kenko 20mm extension tubeNikon Reflex Nikkor 500mm f8 is a reflex telephoto lens for Nikon F mount. Right off the top, mirror lenses have a few "downsides": they don't have an adjustable aperture, and out of focus highlights can take on a donut like appearance. This lens includes a pair of rear mounted ND filters to help moderate exposures, so that's at least some help for the first issue; as for the donuts, well, you may just have to learn to like the donuts. The upside is