Description: High Definition 800mm preset telephoto lens is and incorporates not only computer optical design, but also the latest optical multi-coating techniques. The process of multi-coating assuresvirtually flare free photographs even under adverse lighting conditions resulting in crisp, high contrast pictures. Features: 420-800mm f/8.3-16 Manual Telephoto Zoom Lens. Manual Focus Telephoto Zoom Lens to use with DSLR SLR Cameras. Multi Coated low-dispersion glass, anti-reflection coating. Create Sharp High Quality Images. Comes with Lens Pouch and Protective Caps. Specifications: Lens Construction: 4 Elements in 2 Groups Aperture Range: 8.3-16 Focal length: 420-800mm Minimum Focusing Distance: 1.5m / 4.92ft Filter diamater: 67mm Package size: 27 * 9 * 9cm / 10.6 * 3.5 * 3.5in Package weight: 860g / 1.9LB Note: the 420-800mm zoom lens is fully manual operation, no electronic contactors, that's why camera will not recognize the lens, it requires full manual settings on camera & lens body. Here are some tips to use, 1) Set your camera to M mode with "shutter release: no lens" on(if any); 2) Adjust the lens to your desired aperature/focal length; 3) Fine tune the front focusing ring to make subject in-focus and take a sample picture. If the picture turns out dark, set the following steps, a. Lower the shutter speed, from 1/500s down to 1/100s or slower 1/50 etc; b. Raise the ISO Number, from ISO 100 to ISO 200/400/800 etc. c. Use a remote shutter release and tripod to increase image stability; d. Switch position to allow more environmental light coming through the lens into the camera imaging sensor; It might take time to get the perfect shot you want, just keep practicing and exploring the fun of manual telephoto lens. Package Content: 1 * 420-800mm Lens & 1* T Ring