2 added Newtonian vs. Cassegrain comparison
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As explained in another answer, some of thoseSome telescopes are refractors (lensconvex lens at upper end), and some are reflectors (mirrorconcave mirror at lower end). This Sky & Telescope article discusses the pros and cons of these and other optical designs. Briefly, refractors are low-maintenance but require a multi-element lens to minimize chromatic aberration; reflectors can provide larger aperture at lower cost but may need a little work to maintain the alignment of the mirrors.

The essential feature of a Newtonian reflector is a flat diagonal secondary mirror near the upper end. It folds the light path at a right angle, relocating the prime focus from the upper end of the main tube to a smaller tube on the side. Besides the classical Newtonian design using a parabolic primary mirror, there are Maksutov-Newtonian and Schmidt-Newtonian designs using a spherical primary mirror and adding a refractive element at the upper end to correct spherical aberration.

Cassegrain reflectors instead use a convex secondary mirror at the upper end to put the focus behind a hole in the primary mirror. As with the Newtonian family, there are Schmidt-Cassegrain, Maksutov-Cassegrain, and classical Cassegrain designs. Other reflector designs, e.g. Gregorian, exist but are less common.

There is an important difference between the two Newtonian reflectors in question. The 114mm is a classical Newtonian with a parabolic primary mirror, whose focal length is the same as its tube length, is of the classical design Newton originated in 1668. The 127mm, with a tube only half as long as its focal length, is probably a Jones-Bird variant with a spherical primary mirror and a small corrective lens near the secondary mirror. Aperture wins in theory, but in practice some users of the latter type have been unhappy with it.

In this lineup, the 80mm refractor and the 114mm reflector may be better choices. In addition to the 20mm and 4mm eyepieces that come with them, you might want an 8-10mm eyepiece for medium magnification.

As explained in another answer, some of those are refractors (lens at upper end) and some are reflectors (mirror at lower end). This Sky & Telescope article discusses the pros and cons of these and other optical designs.

There is an important difference between the two reflectors. The 114mm is a classical Newtonian with a parabolic primary mirror whose focal length is the same as its tube length. The 127mm, with a tube only half as long as its focal length, is probably a Jones-Bird variant with a spherical primary mirror and a small corrective lens near the secondary mirror. Aperture wins in theory, but in practice some users of the latter type have been unhappy with it.

In this lineup, the 80mm refractor and the 114mm reflector may be better choices. In addition to the 20mm and 4mm eyepieces that come with them, you might want an 8-10mm eyepiece for medium magnification.

Some telescopes are refractors (convex lens at upper end), and some are reflectors (concave mirror at lower end). This Sky & Telescope article discusses the pros and cons of these and other optical designs. Briefly, refractors are low-maintenance but require a multi-element lens to minimize chromatic aberration; reflectors can provide larger aperture at lower cost but may need a little work to maintain the alignment of the mirrors.

The essential feature of a Newtonian reflector is a flat diagonal secondary mirror near the upper end. It folds the light path at a right angle, relocating the prime focus from the upper end of the main tube to a smaller tube on the side. Besides the classical Newtonian design using a parabolic primary mirror, there are Maksutov-Newtonian and Schmidt-Newtonian designs using a spherical primary mirror and adding a refractive element at the upper end to correct spherical aberration.

Cassegrain reflectors instead use a convex secondary mirror at the upper end to put the focus behind a hole in the primary mirror. As with the Newtonian family, there are Schmidt-Cassegrain, Maksutov-Cassegrain, and classical Cassegrain designs. Other reflector designs, e.g. Gregorian, exist but are less common.

There is an important difference between the two Newtonian reflectors in question. The 114mm, whose focal length is the same as its tube length, is of the classical design Newton originated in 1668. The 127mm, with a tube only half as long as its focal length, is probably a Jones-Bird variant with a spherical primary mirror and a small corrective lens near the secondary mirror. Aperture wins in theory, but in practice some users of the latter type have been unhappy with it.

In this lineup, the 80mm refractor and the 114mm reflector may be better choices. In addition to the 20mm and 4mm eyepieces that come with them, you might want an 8-10mm eyepiece for medium magnification.

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source | link

As explained in another answer, some of those are refractors (lens at upper end) and some are reflectors (mirror at lower end). This Sky & Telescope article discusses the pros and cons of these and other optical designs.

There is an important difference between the two reflectors. The 114mm is a classical Newtonian with a parabolic primary mirror whose focal length is the same as its tube length. The 127mm, with a tube only half as long as its focal length, is probably a Jones-Bird variant with a spherical primary mirror and a small corrective lens near the secondary mirror. Aperture wins in theory, but in practice some users of the latter type have been unhappy with it.

In this lineup, the 80mm refractor and the 114mm reflector may be better choices. In addition to the 20mm and 4mm eyepieces that come with them, you might want an 8-10mm eyepiece for medium magnification.