Lenses
Previously available to Olympus and other Micro Four Thirds cameras from Panasonic and Blackmagic, the Laowa 12mm Fisheye f/2.8 is now available from Venus Optics for APS-C models in the Sony E-mount, Fuji X-Mount and Canon EOS-M lines of mirrorless cameras.
At only $199, the Laowa 4mm f/2.8 Fisheye has a very unique angle-of-view.

With 210 degrees of coverage and 12mm equivalence in full-frame, the circular point-of-view is a different perspective than most have seen. That can add visual dynamics to otherwise dull backgrounds and provide extra supplementals for photography and video.

The focal length has proven a useful choice for b-cameras during weddings, events, sports, nature work, drone photography and competitions as it can catch an entire panoramic scene while also emphasizing and exaggerating foreground subjects such as people and animals.
Venus Optics has provided lens corrections to most image editing software services so that standard rectilinear views can be pulled from the fisheye capture, too.

Photo © Matt Evans
They say that the Laowa 4mm Fisheye is a popular model with drones at a weight of only 0.3 pounds and a lens depth at 1.77 inches.
The lens is also a good choice for VR, virtual video tours and immersive video because only two will provide more than 360 degrees of coverage. Many other video arrays will require four to six cameras and lenses.

It has a fast f/2.8 aperture for shallow depth of field and low-light photography. Remarkably for a fisheye, it can also focus as close as 3.14 inches from the camera sensor.

Related:
Great Lenses for Mirrorless Cameras
Get a Load of the New Glass That’s Coming for Sony Cameras