Περιγραφή
Skywatcher offers a wide range of Newtonian telescopes under the Explorer label. The telescopes are available individually or in combination with a variety of mounts.
BD as in “black diamond”: the Explorer BD series of telescopes are very popular with amateur astronomers because they offer high-quality parabolic optics at a very reasonable price. Many amateur astronomers started with an Explorer BD, and many have remained true to their Newtonian to this day.
The Explorer PDS offer the same mirror optics, but are optimised for astrophotography: a more favourable focal position, thinner secondary mirror support and a focuser with gear reduction for focus adjustment.
MN 190/1000 telescope:
This telescope offers a high light gathering power and extremely high performance for astrophotography and for visual observing. The front Maksutov lens from Schott ensures that the telescope provides a very good image. With a 190mm aperture, the telescope collects about 740X more light than the naked eye alone (for a 7mm fully dilated pupil). The telescope is excellent for very high-contrast Lunar and planetary observing, but also offers great performance for DSO observing. The Maksutov-Newtonian design is a modification of the Newtonian design in that it has a spherical primary mirror with a front-mounted, coated meniscus lens. Although at first sight it is externally similar to a Newtonian telescope, it offers completely different imaging properties.
This telescope has been specifically optimized for astrophotography and offers excellent correction over the entire field of view. Astrophotographers can obtain coma-free, flat-field astrophotos with a CCD camera or a DSLR (e.g. the Canon EOS) – very important for the aesthetics of the image. Even close to the edge of the field of view, stars are imaged as points and not as ‘comets’. The image produced is quite similar to that of an apochromat. The advantage is obvious, because a Mak-Newtonian is many several times cheaper to buy than an apochomat. Also, this type of system does not generate any irritating colour fringes as is common with achromatic objectives. This type of telescope is a so-called ‘closed system’, i.e. once the OTA has cooled down there are no air turbulence to interfere with astrophotography.
The use of diffraction generating secondary mirror spider vanes can also be avoided due to the meniscus lens. The 58mm wide secondary mirror allows a very good field illumination. The F5.3 focal ratio of the telescope is photographically ‘fast’, permitting relatively short exposure times. The 1000mm focal length means most objects can be imaged adequately. The half format chip, as is common in Canon EOS cameras, gives an image field of 1.4° x 1°. A 2 inch ball bearing Crayford focuser, with 1.25 reduction ratio, allows accurate focusing. Heavy cameras can also be safely attached. At only 10kg in weight, the OTA can be used on a large range of mounts. The selection of mount depends on how the OTA is to be used. The Skywatcher EQ-6 Pro mount is highly recommended for astrophotography. The OTA is also visually a real gem, featuring an elegant design for the both OTA and finder scope in an aesthetically pleasing shimmering black.
The advantages in a nutshell:
- closed OTA with multi-coated meniscus lens
- optimally suitable for astrophotography
- Schott glass used
- adjustable secondary mirror
- large, flat field of view
- ‘fast’ focal ratio
Included in delivery:
- 8×50 finder scope, 90° angled for upright image
- mounting shoe
- 2 inch Crayford focuser and 1.25 inch compression ring reduction adapter
- Tube ring clamps
- T-2 adapter
