Walimex 500/6.3 DSLR mirror Pentax K

Normally, a long focal length of 500mm is accommodated in a mount of 500mm length. To achieve a handy, universally applicable, and compact solution, a trick was used for this lens. The beam path is simply "folded" using two high-precision ground ring mirrors. This results in a compact design and an aperture that is more than 50% higher than that of a lens with the same focal length, along with a very short closest focusing distance of only 2 meters. The focusing is manual. The lens can be used with aperture priority or manual exposure, depending on the camera. It is technically not possible to insert an iris diaphragm into the folded beam path. If light reduction is necessary, this can be achieved using gray filters, which are screwed in front of the rear lens. There is an M34x0.5 thread for this purpose.

The lens has no fixed infinity stop. Focusing is performed "oscillating" by safely finding the focus point from unsharp to sharp to unsharp. The T2 adapter is screwed onto the optics, then the lens is locked. After loosening the side screws on the T2 adapter, the lens can be "straightened" so the index can be aligned to the top. Tightening the screws again reliably secures the lens and adapter.

Advantages of a full-frame lens on a camera with an APS-C sensor include saving time in post-processing. Many lens aberrations like distortion, edge blur, or vignetting occur at the outer areas of the image. Using a lens designed for full format on a camera with an APS-C sensor means these areas are not utilized, thus obtaining maximum quality. Additional post-processing time to correct lens errors is therefore not necessary.