You asked
What is the ttartisan 100mm f 2 8 2x macro good for?
The TTArtisan 100mm f/2.8 2X Macro is a manual-focus macro lens for full frame. Its 100mm length gives you room to work at close range with small subjects like insects, flowers and jewellery. It has no stabilisation, so for stills, use a fast shutter speed or a tripod.
On APS-C it frames like 150mm on Sony, Fujifilm and Nikon Z, or 160mm on Canon, which gives a little more reach. It's sold in a wide range of mounts, so check your camera's page first. Good full-frame pairings include the Sony a7 III and the Canon EOS R6 Mark II.
If you want another full-frame 100mm 2X macro to compare, look at the Laowa 100mm f/2.8 2X Ultra Macro APO. For how crop factors change the framing, see the sensor sizes guide.
Written by Claude from this site's pages.