Jupiter-21A has Sonnar optical design (4 lenses and 3 groups). All Jupiters have this design. The elements have a single coating and is one of the best Soviet telephoto lenses.
In 1973, the manufacturer changed to Optical Vologda and Mechanical Plant (VOMZ) and it was changed to Jupiter-21M. It was designed for the M42 system, added automatic preset opening, was modified to a thicker barrel and the lens became heavier 240 grams more, and the number of opening blades was reduced to 8. All this made the Jupiter- 21M shows worse optical performance over all in sharpness and contrast.
|Angle of coverage||12º Full-frame|
|Image Format||Full-frame / 35mm|