About Peleng 8mm f/3.5 Fisheye

There are two possible kinds of fisheye lenses, you can see them further. Peleng fisheye represents the second kind. Soviet photographers used the film in another way that's why the circle of picture cannot be placed inside the 35 mm entirely even in cameras with regular film. Digital cameras still have the lens limitation of 180 degrees which can be noticed in the corners and their advanced photo system sensors can capture even less images.
1. Full frame fisheyes take half-spherical picture bias the 35mm film. 14-16 mm focal length is peculiar to them.
2. Lenses with 6-8 mm focal length capture spherical images, seizing full 180 degrees. The whole picture is placed inside the narrow film stripe.
Here are Sumire and Rui who were caught by my Peleng 8mm f/3.5 Fisheye.

If you are a Peleng 8mm owner you might have already bought an adapter because without it lens cant be mounted. It is quite common that this lens is furnished with M42 adapter, mine was also furnished with a special Nikon adapter. As you know, M42 lenses demand an adapter from M42 to K bayonet if the matter concerns digital cameras. I supposed that I may want to try it on Pentax Takumars so I chose a separated variant instead of more expensive purchase of it in kit with the lens. [NOTE: At this time BelOmo make Peleng with Canon, Nikon and Olympus mount. And you can use Peleng without any adapters]
There is a felt line on the internal edge of the lens which has to provide the stability of the front cap. By the way, this material is pretty thin so the cap is rather useless and doesn't make sure that the cap is where it should be. For this purpose I use a rubber edge. Not perfect but it works.
On the lens picture you may see something very special. I mean, it has the ring which opens and closes the aperture to the real value of it. In other words, there is a ring which locks and unlocks the diaphragm.
Peleng 8mm Lens is designed for manual setting I heard that some photographers have damaged camera mirrors because soviet lenses have too big lug on their back. However, I know the one who was happy user of it with Pentax camera. Of course, I doubted if I could mount lens without any harm to the mirror of my camera so I had measured it. The biggest lug is 10 mm behind the bayonet edge. When I focused on the infinity, I measured 8,5 mm. That's why you do not have to be afraid: there is a sufficient space.

The M42 adapter, furnished with the lens and the adapter from M42 to K bayonet made by another producer
With the help of the screw mount there will be no problems in turning, placing and removing the lens. You can see a little spring on the adapter which helps you do all these operations. When the lens is mounted, this spring catches it so there won't be any rotations if the lens is not screwed. Outside the spring it has a little tool needed to remove an adapter. So you will have to insert this tool in a special place to detach the spring. I have to mention that if you try to rotate the adapter to the right the tool will prevent removing of it by engaging the edge of the bayonet.
Summarising said before, here is what is necessary to do all this: detach the adapter from the lens, use the special removal tool in two holes on the adapter, turn it to the right until it stops, raise the tool while it can be rotated but until it sets the stop, detach the M42 adapter.
Certainly, you need some skills to do it so you'd rather experience it in a clear dry room before trying it outside where is dusty and wet. I have even bought the Pentax lens which can be easily screwed because outside it was too difficult to mount the lens to the adapter. But of course, it is much more simpler just to get rid of this spring.
Samples

Tracks of this crane are very curved
Photographer feet were out of the captured image which measures 180 degrees
If you rotate your camera with the Peleng lens mounted on it you will be able to observe everything sideward

Characteristics

Lens construction: 11 elements in 7 groups
Angle of view: 180° diagonally on film camera
Number of diaphragm blades: 9
Minimum aperture: f/16
Minimum focusing distance: 0.22m
Filter size: 26.5mm rear mount (three filters included)
Maximum magnification: 0.13X
Dimensions (diameter x length): 73mm x 65.5mm
Weight: 370g
Enjoy your fisheye lens!