Usually a long focal length of 800mm also has a total length of almost 80cm to the sensor level.

In order to obtain a handy, universally applicable and compact solution, a trick was used with this lens. The beam path is simply “folded” by means of two high-precision ground ring mirrors. This results in this compact design of only 131mm in length – compared to the almost 80cm mentioned. The closest focusing distance is also reduced to 3.5 meters instead of at least 10 m with a lens.

The focus is done manually. The lens can (depending on the camera) be used with aperture priority or manual exposure setting.

It is technically not possible to use an iris diaphragm in the folded beam path. If light reduction is necessary, this is made possible simply by using a gray filter 2x or 4x. These are screwed in front of the rear lens. There is a M30.5×0.5 thread for this purpose.

Practical: the lens does not have a fixed, defined infinity stop. Focussing is carried out “pendularly” in that the focus point is reliably found from unsharp through sharp to unsharp at any distance.

T2 connection, operating tip: The T2 adapter is screwed onto the optics, then the lens is bolted on. The screws on the side of the T2 adapter allow the lens to “straighten up” after loosening it – aligning the index upwards. Tightening the screws again reliably secures the optics and adapter.

Advantages of a full frame lens on a camera with an APS-C sensor
Save time in post-processing. A large number of lens defects such as distortion, edge blurring or vignetting occur on the outer areas of the image. If you use a lens calculated for full format on a camera with APS-C sensor, these areas are not used. So you get the maximum quality. Additional post-processing time for correcting lens errors is therefore no longer necessary.

General Information

Technical specifications

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