I bought the 42mm screw-mount version, because I can adapt it to several cameras, including digital. It's reasonably fast at f/2.5.
This is a two-part lens: the lens and the macro adapter that allows for 1:1 capture. Without the macro adapter, it focuses to 1:2. The macro adapter is more than an extension tube and uses three elements in two groups. Vivitar called it a "null" lens."
The adapter has its own tripod mount, and a knob on the side allows you to rotate your camera up to 90 degrees.
You often find the lens sold without the adapter. It also came with a case, which I didn't receive. Additionally, I've bought a lens hood, because a lens hood is always a good idea.
This is a substantial lens in terms of weight. The lens weighs 1.5 pounds, while the adapter weighs 1/2 pound, bringing the total to 2 pounds.
Here are some photos of the lens next to a ruler and also mounted to a Sony A7 II.
As a portrait lens, it should be fine with smooth out-of-focus areas gradually falling off. I've used the Vivitar Series 1 28mm, and shots wide open can be quite harsh. I'll post some sample photos from that lens some time.
I still think macro lenses work best when the camera is mounted on a tripod, because as you know, macro shooting magnifies camera shake. Just a couple of sample shots. When I zoomed in on these, I was impressed with the resolving power of the lens.
These were all shot without the macro adapter. I'll need the tripod for that test. On most of these, I stopped down to f/5.6 or f/8 to get some additional depth of field. These were shot at either ISO 400 or 800.
