GSO Dobson 8 203/1200 CRF Dobsonians opinie

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The GSO Dobson 8" 203/1200 CRF telescope is the first serious competitor to the popular "Synta 8" in years. Equipped with a high-quality main mirror in the shape of a rotating paraboloid, with a diameter of 203 mm and a focal length of 1200 mm (light f/6). The Taiwanese GSO factory is a recognized supplier of high-class optics, with diffraction-limited quality (i.e. the quality of images is limited only by the nature of light). The telescope allows you to obtain excellent images of both solar system objects and star clusters, nebulas and galaxies.

The typical, simple concept of Dobsonian telescopes has been optimized in the GSO series telescopes by using several useful design improvements not available in competing models.

Observation possibilities

The GSO Dobson 8" 203/1200 CRF telescope is a universal tool for conducting advanced visual observations of all types of astronomical objects. It will work well in all observation conditions, but - like any astronomical telescope - it loves dark, rural skies and will show the most under such a sky. .

During observations, we can count, among others: for very successful observations of the following objects:

• craters on the Moon - countless formations, excellent plasticity around the terminator
• phases of Mercury and Venus - in the case of the latter, you can try to observe delicate formations of its atmosphere
• ice caps on Mars are very visible (it is worth buying red, orange and yellow filters)
• belts in Jupiter's atmosphere with their structure, both "tropical" and circumpolar, the Great Red Spot, four Jupiter moons
• Saturn's ring with the Cassini gap and Encke gap, belts
• shields of Uranus and Neptune
• many asteroids, including the brightest Ceres and Vesta
• comets - ice blocks traveling through the Solar System
• hundreds of double, multiple and variable stars
• hundreds of Deep Sky objects, including all from the Messier catalog, as well as many from the NGC, IC and Caldwell catalog; therefore, open clusters will be visible, such as the Manger in Cancer, hi chi in Perseus or the Ptolemy Cluster in Scorpio, globular clusters (M13 broken up to 1/2 of the diameter into single stars, or M53 in the Coma of Berenice), gas-dust nebulae ( perfectly visible structure of M42 in Orion, North America in Cygnus), galaxies (M31 in Andromeda along with two satellite galaxies, i.e. M32 and M110), supernova remnants (such as Veil in Cygnus or the famous Ring (M57) ) in Lutnia) and much, much more.

In addition to astronomical observations, this telescope is great for observing and photographing aircraft at cruising altitudes.

Tube

The telescope tube is made of metal and appropriately stiff, and the precise and solid frames of the primary and secondary mirrors ensure long durability of the telescope's collimation. The matte, carefully blackened interior of the tube minimizes reflections and light wandering around the optical system, thus ensuring higher contrast of the obtained images (this is especially important when observing the Moon, planets and bright stars).

Dobsonian assembly

The weight and dimensions of the telescope are acceptable in relation to the observation possibilities and the size of the mirror - the tube fits in the back seats of most passenger cars.

Using the telescope is very simple and it is easy to assemble and operate by one observer. Like any telescope with a box Dobson mount, the orientation to the object takes place in two axes - the azimuth axis (horizontal) and the altitude axis (vertical). In the azimuth axis, rotation takes place on Teflon washers, and in the height axis - on Teflon washers with a spring regulating the pressure.

Spectacle extractor

The telescope is equipped with a high-quality Crayford extractor adapted to standard 2" and 1.25" glasses.

Advantages of the Crayford focuser:

• much smoother and more precise focusing movement compared to simpler sliding and rotary focusers
• thanks to the use of a brass ring ( clamping ring ), the mounting of the glasses becomes more secure, the axiality is perfectly preserved, and scratching the surface of the glasses sleeve is avoided

Main mirror cooling

The telescope is equipped with a 12V fan attached to the end of the tube, which, when turned on, greatly accelerates the equalization of the temperature of the telescope mirror with the ambient temperature.

Set

• optical tube on a Dobson mount mounted on Teflon, with a spring regulating the pressure in the height axis
• Plossl eyepiece 25 mm / 1.25" (48x magnification)
• Red Dot collimator finder
• Crayford lift 2" / 1.25"
• sleeve 35 mm / 2"
• a fan that accelerates the cooling of the main mirror
• shelf for accessories

THE OFFERED TELESCOPE ALLOWS YOU TO START OBSERVATIONS ON THE FIRST WEATHER NIGHT - IT CONTAINS ALL NECESSARY ACCESSORIES, THE OPTICAL TUBE OPTICS IS APPROPRIATELY ADJUSTED, THE SET INCLUDES 1 EYELAY AND A DOBSON INSTALLATION; IT IS WORTH BUYING 1-2 GOOD QUALITY GLASSES FOR THE SET - FOR EXAMPLE WITH FOCAL FOCALS OF 15 AND 6MM

Usage

Moon

planets

star clusters

nebulae

planes

Technical parameters

Guarantee

2 years

Additional photos

(GSO 8" telescope - front view)




(GSO 8" telescope - rear view)




(8" mirror, i.e. 203mm; secondary mirror mounting - so-called "spider" - with thin arms)




(2" focuser made using CNC technology, accepts 2" and 1.25" glasses)




(extract with 2" eyepiece attached)




(the focuser is equipped with a millimeter scale for faster and more precise focusing for accessories known to the user)




( star pointer collimator finder)




(tube clamping system for Dobsonian installation)




(accessory shelf: 35 mm / 2" adapter and PL 25 mm 1.25 eyepiece)




(mirror cooling system, comfortable collimation screws)




(movement of the Dobsonian assembly along the height axis, i.e. "up - down")




(movement of the Dobsonian assembly in the azimuth axis, i.e. "left - right")

Question : Is the mirror made of Pyrex? Is there a version with a Pyrex mirror? Is BK-7 Pyrex? Which is better, Pyrex or BK-7? Why isn't the mirror made of Bak-4 glass?

Answer: Pyrex is the trade name for boron-silicon offered by Corning. Many companies offer glass with the same composition and parameters, but borosilicate glass is often referred to as Pyrex (a bit like Adidas for sports shoes). A characteristic feature of this glass is that its thermal expansion coefficient is approximately three times lower.

From the point of view of an astronomy enthusiast, its advantage is that it achieves the figure slightly faster when cooling the telescope, e.g. after taking it out of the house to a frosty yard. It should be noted that the use of Pyrex in amateur telescopes (6" - 16") is not necessary, because these mirrors are quite thin and cool down quickly. However, cooling the mirror and achieving the appropriate shape is not everything - the tube must also reach the ambient temperature, otherwise turbulence will appear inside the tube and the image will be of poor quality. In practice, it is important that the ENTIRE telescope is at a temperature close to ambient temperature.

BK-7 is a good optical glass, also commonly used in the best optical systems. It is not bad glass, as is sometimes believed. Moreover, from the point of view of the user of the Newton system telescope, the optical characteristics of the glass are irrelevant - the important element is the shape of the mirror and the properly applied reflective layer. The physical characteristics of the glass may be important - the mirror itself is only a "support" for the reflecting layer.

To answer briefly:
• no, the mirrors of GSO telescopes are not made of Pyrex, they are made of BK-7 glass
• BK-7 is not Pyrex
• Pyrex is more expensive, but its use must be justified; in the case of a cooled telescope, there are no differences in the images obtained between Pyrex and BK-7
• BaK-4 is quite expensive optical glass, with a high refractive index, used almost exclusively in prisms (scopes, binoculars, in angle connectors with an Amici prism, etc.), of little use and rarely used in lenses and glasses
• the presence of active cooling ("fan") on the back of the mirror shortens the mirror cooling time to 15 - 30 minutes, thus eliminating the difference between BK-7 and Pyrex.