The compact mirror lens classic An 800 mm lens is normally almost 80 cm long. This model uses two precisely ground ring mirrors to fold the beam path and thus enable a compact design of only 131 mm in length. The close focus distance is only 3.5 metres compared to at least 10 metres for conventional lens objectives. Manual focussing for precise settings The lens has a manual focussing system that enables precise image control. Depending on the camera, it can be used with aperture priority or manual exposure, which allows flexible adaptation to different situations. Efficient light reduction without iris diaphragm A conventional iris diaphragm cannot be integrated into this mirror lens. Instead, the light is reduced using screw-on 2x or 4x grey filters. These are mounted in front of the rear lens, for which an M30x05 thread is provided. This allows the exposure to be optimally adjusted. Oscillating focus adjustment for precise focussing This lens does not have a fixed infinity stop. The focus is set by oscillating - the focal point is adjusted from out of focus to in focus and back to out of focus - precise focussing at any distance. Robust T2 connection with adjustment option The T2 adapter is securely screwed onto the lens and the lens is locked in place. Side screws allow the index to be adjusted upwards. Once tightened, the lens remains stable and reliably connected to the camera. Advantages of a full-frame lens on an APS-C camera As an APS-C sensor only utilises the central image area, edge blurring, distortion or vignetting are avoided. This maximises image quality and eliminates the need for additional post-processing to correct these lens errors.