Anamorphic lens is an adapter that attaches to the taking lens (your lens). It is a real anamorphic adapter compressing the image.
Anamorphic adapter attach in front of the taking lens. Focusing is done the taking lens, the adapter has a through single focus.
The adapter is able to focus on lenses from 20 mm to 85 mm and has a mount 67 mm in diameter.  Attachment of the adapter is carried out directly to the taking lens or through a special clamping device (clamp) to align the adapter horizontally. The clamp is sold separately, made in a simple ring design with external and internal thread and the ability to fix in the desired position with adjustable or hidden bolts.
Anamorphic adapter can be installed on any lens with different diameters using adapter rings to 67 mm (mount of anamorphic adapter). It is desirable that the diameter of the front lens of the taking lens was less than 60mm. If it is more, may experience vignetting and spherical aberration.
Lenses with the best sharpness are 37mm 2.8, 40mm 2.8, 45mm 2.8, 50mm f2, 55mm f2. 58mm f2.8.
Anamorphic adapter works with zoom lenses. Values may vary for zoom lenses, vignetting may occur at a slightly longer focal length. If the front filter of your lens rotate - then the installation of the anamorphic adapter will have to be undertaken on the rig (cage) next to the lens. The anamorphic adapter must not rotate during shooting, otherwise the horizontal compression ratio will change.
Budget versions of anamorphic adapters are more suitable for art shooting. They are less versatile because they are slightly longer. They have a little more distortion.
For camera crop factor of MFT (crop 2, micro 4/3) is better suited Compact anamorphic adapter. For Full frame cameras is better suited the Bigmetal adapters. Format APS-C (crop 1,5) is universal for anamorphic shooting.
 
Compact 1.33x rev.2 is ideal suited for widescreen video shooting on cameras installed on stedikam, multicopter. As well as on other systems that require the size and weight of the installed equipment.
Adapter is enclosed in a metal case with combined optics – glass and polymer. Compression ratio is about 1.33x. The lenses have a multi-lightening, anti-reflective or other coating.
The center of gravity is conveniently offset to the mounting edge of the adapter (to camera case), which is very well suited for various stabilizers, copters and stedicams. 
The diameter of the anamorphic adapter is 74 mm. The diameter of the front lens is 70 mm. There is also 72 or 77 mm thread for filter (macro filters may be used to shoot very close objects).
The adapter can work with full-frame cameras, but spherical aberrations increase in this case. Spherical aberrations is looking as blurring on the edge of the frame. In fact, they are the focus shift closer to the camera. They create a beautiful effect of a dedicated center and a beautiful bokeh.
It is better to use the adapter for APS-C and MFT crop cameras. The adapter is suitable for the Canon 35mm, Canon 50mm 1.8, 40mm 2.8, MIR-1B 37mm and similar lens on APS-C format. There is no vignetting in the full frame with a focal length of 50 mm and on the crop sensor 1.6 and 1.5 with a focal length of 35 mm. On the crop sensor 2 (micro 4/3, 16 mm sensor) there is no vignetting at a focal length of 25 mm.
Given values are for fixed focal length lenses. Values may vary for zoom lenses. It is desirable that the diameter of the taking lens front element is less than 60 mm. It is also necessary to use very clear and sharp lenses as the anamorphic adapter greatly reduces the depth of field (it is harder to focus), slightly blurs the image around the edges.
The best performance adapter shows on lenses with a focal length of 25mm to 65mm on cameras with a crop factor of 1.5 or 2 (APS-C or MFT).
Spherical aberration is more pronounced on a full frame. Blurring at the edges is well suited for close-up portrait photography with a CloseUp filter. It looks like a beautiful wrapping of the picture on the edges of the frame, there is an allocation of the object in the center.
The maximum sharpness of shooting is achieved at a distance of 10 – 20 meters, when the focus is 20 mm to 80 mm. At a distance closer than 3m, it is necessary to use diopters +0.3/+0.5. If necessary, close-range shooting, if there are no diopters – you can clamp the diaphragm of the taking lens. The sharpness at infinity is in acceptable quality.
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There are examples of videos on YouTube and Vimeo.

Length - 65 mm, diameter - 74 mm, mounting - 67 mm. Weight ~ 170 grams.

The adapter does not have a clamping device included.