This is a like-new Vivitar Series 1 7mm F/3.5 fisheye lens for Nikon DX (APS-C) DSLR cameras. Made by Samyang; if you're familiar with them, they make these fisheye crop-sensor lenses under several badges, including Rokinon, Vivitar, Bower, Opteka, etc.
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Manual focus. There's so much depth-of-field, however, that it's almost impossible to take an out-of-focus picture with it. The "rangefinder" focus indicators in your viewfinder will also tell you when the subject is in focus. It is a crop-sensor (DX) lens, so if you mount it on a full-frame camera, you'll see some vignetting.
UPDATE: This lens WILL work on a full-frame (FX) camera, if used with a teleconverter. Just for S&G, I tried it with a Tamron 1.4x, on a full-frame D750. It worked GREAT, no vignetting. With a 1.4x, it's effectively a 10mm F/5.0 lens, which is a VERY wide angle lens for a full-frame camera. I shot the Milky Way photo this way; it's nearly horizon-to-horizon.
This lens is like new and complete in its original box, including both caps, the owner's manual, and a little drawstring pouch. I've taken very few pictures with it; no more than 50, I estimate.
We can meet at a coffee shop other public hangout downtown, or near-east, or I can travel if it's not too far.