Normally, a long focal length of 800 mm also has an overall length of nearly 80 cm to the sensor plane. To achieve a handy, versatile, and compact solution, this lens employs a clever trick. The light path is simply "folded" using two high-precision polished mirrors. This results in a compact design of only 131 mm in length compared to the mentioned nearly 80 cm. The minimum focusing distance is also reduced to 3.5 meters instead of at least 10 m with a lens-based system.

Focusing is done manually. The lens can be used (depending on the camera) with automatic exposure or manual exposure settings. In the folded light path, it is technically impossible to incorporate an iris diaphragm. If light reduction is necessary, this is simply achieved using 2x or 4x neutral density filters, which are screwed onto the rear lens. There is a thread M30x0.5 available for this purpose.

Practical: The lens does not have a fixed defined infinity stop. Focusing is done "pendulum-style," allowing the sharp point to be confidently found from out of focus to sharp and back to out of focus at any distance.

T2 connection, operating tip: The T2 adapter is screwed onto the optics, and then the lens is locked in place. The side screws on the T2 adapter allow for the lens to be "uprighted" after loosening, aligning the index upwards. Retightening the screws securely fastens the optics and adapter.

Advantages of a full-frame lens on a camera with an APS-C sensor: Save time in post-processing. Many lens errors such as distortion, edge softness, or vignetting occur in the outer areas of the image. When using a lens designed for full-frame on a camera with an APS-C sensor, these areas are not utilized. Thus, you achieve maximum quality.