Meniscus lens of a Maksutov-Cassegrain (MAK)

Here you can see the meniscus lens of a Maksutov-Cassegrain (MAK). This corrects spherical aberration and thus produces sharper images than a comparable Schmidt-Cassegrain (SC). The image is thus virtually free of "chromatic aberration" and tends to be sharp and high-contrast, provided the lenses have been precisely aligned.

Due to the thickness of the lens, the cooling time is quite long. They are very stable in alignment and, thanks to their short design, can be used well even on smaller mounts. They are also suitable for air travel and can be carried in a backpack. Only relatively small fields of view can be achieved, and the obstruction by the secondary mirror is relatively large. A very good planetary telescope. Less suitable for deep sky observation, as the focal length is relatively long at f/10 to f/15.

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