The ultra-compact, handy travel telephoto lens with a focal length of 300 mm becomes an indispensable companion. Both distant and detailed shots are easily achievable, thanks to the practical close focusing distance of 0.90 m. This is made possible by its design as a mirror lens. The lens not only has a higher light intensity (1:6.3) than comparable lens systems, but it is also very portable: with a length of approximately 74 mm and a weight of 318 g, it means you can always have it with you. This is achieved through an optical trick: the light path, which is typically 300 mm long, is simply "folded" using two precision-ground mirror rings. If light reduction is necessary, it can be done using a gray filter M 25.5 (not included), which screws onto the rear lens. Due to its design, it also offers excellent color reproduction: there are only very few lens elements that cause chromatic aberrations. Lenses designed for cameras with APS-C sensors can partially (mainly using an adapter) be used on full-frame cameras. However, due to the significantly smaller image circle of APS-C lenses, the edges will appear black. Therefore, the usable area of the image taken with a full-frame camera corresponds to that of a camera with an APS-C sensor. The images will need to be cropped in post-processing. While it is possible to use APS-C lenses on full-frame cameras, it is not recommended.