The openness of following case has been allowed by our clients with exception of key parameters, which is only 90% of complete design process. I. Application 50 mm standard lens with whole picture, bayonet 39 mm, flange distance 28.8 mm II. Rquirements Applicable wavelength: visible light EFL: 50 mm Lens quantity: no more than 6 pieces Lens maximum diameter: less than 25 mm Lens facial type: all spherical Lens material: optical glass Lens gross weight: less than 80 g Viewing angle: 46 degrees Maximum aperture: 2 Rear intercept: more than 27.8 mm Total length (first len to image surface) : less than 65 mm Maximum distortion: less than 2% Resolution: more than 50 lp/mm@0.3 F / 2 relative illumination of side FOV : more than 65% Focusing mode:  Variable aperture available III. Features The application of standard double gaussian lens and rear intercept required is for shutter and mirror device installation of carmera. This lens system has vignetting,  relative illumination of FOV with 23 degress is 71%, while F4 has no vignetting. IV. Result