Full Manual Telephoto Lens: 420-800mm telephoto lens, no adapter ring required, 2 seconds fast lens mounting. After installing the lens, you need to perform a full manual focus operation on a digital SLR camera: 1. Adjust to M mode for use. 2. Twist the lens focus ring to focus, and adjust the ISO and shutter speed. (Lens aperture is not adjustable, it changes with the focal length). Using a manual lens gives you complete creative control over your images and provides unrivaled creative expression and versatility; | EF Lens for Canon: EF telephoto lens is perfect for photographing elusive wildlife, birds, the moon and other distant landscapes and small objects, bringing you closer to your subject to unprecedented distances. EF lens for Canon EOS Rebel T8i T7 T7i T6 T6s T6i T5 T5i T4i T3i T3 T2i T1i SL3 SL2 XSi; EOS 10D 20D 30D 40D 50D 60D 70D 80D 90D 100D 200D 250D 300D 350D 400D 450D 500D 550D 600D 650D 700D 750D 800D 850D 1000D 1100D 1200D 1300D 1500D 2000D 3000D 4000D 9000D/77D 760D/8000D 1D X Mark III/II/1DX, 5D Mark IV/III/5DS/5DS R, 6D Mark II/6D, 7D Mark II and other ef camera; | Attention to Image Stabilization: The telephoto lens has no auto focus and image stabilization, slight camera shake will greatly affect the image quality, it is recommended to use time-lapse shooting, tripod or shutter release cable to stabilize the image and take beautiful pictures. Manual focus telephoto zoom lens is recommended for professional photographers, suitable for digital SLR cameras, not for mirrorless cameras; | Resolving Overbright/dark Tips: You can start by focusing and metering at a position determined as the exposure reference using a long focal length, then locking the exposure and then changing the focal length to take the picture. If the photo is too dark, you can remedy the situation by the following methods:1) Reducing the shutter speed from 1/500 sec. to 1/100 sec, or slower, such as 1/50 sec, 2) Increasing the ISO value from ISO 100 to ISO 200/400/800, etc, 3) Switching the position so that more ambient light enters the camera's imaging sensor through the lens; | Warm Tips: 1) Lens Not support for Canon EOS R, Ra, RP, R3, R5, R5 C, R6, R6 Mark II, R7, R8, R10, R50, R100 | EOS M, M3, M5, M6, M6 mark II, M10, M50, M100, M200. 2) Not suitable for sports photography. 3) Avoid as much as possible prolonged exposure of the lens to windy sand and the presence of large amounts of dust in the environment.Prolonged contact with humid air can cause mold to form on the lenses, which may affect their use. If the ambient humidity is high, the use of a drying box is recommended.