Since this is a classic M39 thread, it's much easier and cheaper to use with modern mirrorless cameras than the Contax mount. You no longer need a complicated adapter with its own helicoid. 

 A ​​standard adapter ring with standard markings will work: 

M39 - NEX / E-mount (for Sony) 

M39 - FX (for Fujifilm) 

M39 - M4/3 (for Olympus/Panasonic)

 M39 - NZ (for Nikon Z)

 M39 - EOS R (for Canon)

Title: Vintage Soviet Lens Jupiter-8 50mm f/2 (M39 / LTM mount) – Red "P" – KMZ 1957

Description:Up for sale is a rare, early production Soviet rangefinder lens Jupiter-8 50mm f/2 in a classic silver aluminum body. Made in 1957 at the famous KMZ factory (Krasnogorsk), USSR.This is the legendary copy of the German Carl Zeiss Sonnar 50mm f/2. It features the famous Red "P" (П) marking, which stands for special anti-reflective chemical coating, providing beautiful vintage contrast and character.

Specifications:

Focal length: 50mm

Max Aperture: f/2.0Mount: M39 / LTM (Leica Thread Mount). 

Standard 28.8mm registration distance for Zorki, FED, Leica RF cameras. Can be easily adapted to any modern mirrorless system (Sony E, Fujifilm X, Micro 4/3, Canon RF, Nikon Z) via cheap adapters.

Serial Number: 5701827 (Built in 1957)Focusing: 

Features an early-type focusing lever ("tab") on the barrel.

Condition:

Cosmetics: Good vintage condition with some minor signs of age and use on the silver aluminum body (please see photos).

Optics: Glass is clear for its age. No visible fungus.

Aperture & Focus: Aperture ring rotates smoothly. The multi-blade iris creates a perfectly circular aperture for beautiful round bokeh. Focus ring moves well.Package Includes:Jupiter-8 50mm f/2 lensFront lens cap

Worldwide shipping with tracking number. If you have any questions, feel free to ask!