GSO Dobson 8 DeLuxe 203/1200 M-CRF Newtonians opinie

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The GSO Dobsonian 8" DeLuxe 203/1200 M-CRF telescope is equipped with a high-quality primary mirror in the shape of a rotating paraboloid, with a diameter of 203 mm and a focal length of 1200 mm (f/6). The Taiwanese GSO factory is a renowned supplier of high-class, diffraction-limited optics (i.e. the quality of images is limited only by the nature of light). The telescope allows for obtaining excellent images of both Solar System objects and star clusters, nebulae and galaxies.

The typical, simple concept of Dobsonian telescopes has been optimized in the GSO DeLuxe series telescopes by implementing a number of useful design improvements.

Observation possibilities

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

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

• craters on the Moon - countless formations, excellent plasticity in the vicinity of the terminator
• phases of Mercury and Venus - in the case of the latter, one can try to observe the delicate formations of its atmosphere
• ice caps on Mars very clearly visible (it is worth buying red, orange, yellow filters)
• belts in Jupiter's atmosphere and their structure, both "tropical" and circumpolar, the Great Red Spot, four of Jupiter's moons
• Saturn's ring with the Cassini and Encke divisions, belts
• shields of Uranus and Neptune
• many asteroids, including the brightest Ceres and Vesta
• comets - icy blocks that travel through the Solar System
• hundreds of double, multiple and variable stars
• hundreds of Deep Sky objects, including all Messier objects, as well as many from NGC, IC and Caldwell; so you will see open clusters like the Crib in Cancer, Hi Chi in Perseus or Ptolemy's Cluster in Scorpius, globular clusters (M13 broken down to 1/2 of its diameter into individual stars, or M53 in Coma Berenices), gas-dust nebulae (the perfectly visible structure of M42 in Orion, North America in Cygnus), galaxies (M31 in Andromeda with its two satellite galaxies, M32 and M110), remnants of a supernova explosion (such as the Veil in Cygnus or the famous Ring (M57) in Lyra) and much, much more.

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

Tube

The telescope tube is made of metal and is suitably rigid, while the precise and solid frames of the primary and secondary mirrors ensure long-lasting collimation of the telescope. Matte, careful blackening of the interior of the tube minimizes reflections and stray light in the optical system, thus ensuring higher contrast of the obtained images (this is especially important when observing the Moon, planets and bright stars).

Dobsonian mount

The weight and dimensions of the telescope are acceptable in relation to the observing 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 there is no problem with assembly and operation by one observer. Like any telescope on a Dobsonian box mount, the setting to the object is done in two axes - the azimuth axis (horizontal) and the elevation (vertical). It differs from competing solutions by definitely better bearings in the azimuth - these are roller bearings, guaranteeing on the one hand the smoothness and lightness of the "walk" of the structure, and on the other - higher precision of setting. Metal bearing tracks prevent biting into the wood of the mount, thanks to which a high durability of the mount structure has been achieved. In the elevation axis there is a new bearing system developed by GSO. The telescope is guided and held by two handles. The desired pressure is adjusted using knobs located on both sides of the mount. This is especially helpful when changing the eyepiece to maintain position and balance. Additionally, the telescope has the ability to correct balance by changing the height of the mount.

Spectacle focuser

The telescope is equipped with a high-quality Crayford focuser with a microfocuser with a 1:10 gear ratio. Thanks to this, focusing is very precise even at high magnifications. The focuser is adapted to standard 2" and 1.25" eyepieces.

Advantages of the Crayford focuser:
• much smoother and more precise movement when focusing compared to simpler sliding and rotating focusers
• thanks to the use of a brass ring ( clamp ring ), the attachment of the glasses becomes more secure, the axial alignment is perfectly maintained and scratching of the surface of the glasses sleeve is avoided

Main mirror cooling

The telescope is equipped with a 12V powered 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 Dobsonian mount with ball bearings
• Crayford extractor with microfocuser 1:10
• 30 mm wide-angle Erfle eyepiece (AFOV 70°) / 2" and 9 mm Plossl eyepiece (AFOV 52°) / 1.25"
• 8x50 finder with crosshair
• fan to accelerate cooling
• 35 mm 2" / 2" sleeve with 2" filter thread
• reduction from 2" to 1.25" with brass ring and 2" filter thread (M48x0.75)
• dust cover for the front of the tube

THE OFFERED TELESCOPE ALLOWS YOU TO START OBSERVATIONS ON THE FIRST CLEAR NIGHT - IT INCLUDES ALL NECESSARY ACCESSORIES, THE OPTICAL TUBE OPTICS ARE PROPERLY ADJUSTED, GLASSES AND A DOUBLE MOUNT ARE INCLUDED

Applications

Moon

planets

star clusters

nebulae

planes

Technical parameters

Guarantee

2 years

Additional photos

(GSO Dobsonian 8" Deluxe Telescope - Front View)




(GSO Dobsonian 8" Deluxe Telescope - Rear View)




(main mirror diameter 203mm; secondary mirror mount - so-called spider - with thin arms)




(8x50 finder, Crayford focuser with planetary gear 1:10)




(attaching the tube to the mount, controlling the tube pressure using knobs; it is possible to move the tube attachment point to obtain optimal balance for a given set of accessories)




(Crayford focuser with 1:10 microfocus)




(2" focuser with 30 mm / 2" Erfle eyepiece, visible millimeter scale on the focuser)




(8x50 finder with cross, straight)




(main mirror cooling system - fan powered by 8xAA, i.e. 12V; main mirror frame with full collimation adjustment)




(glasses/accessories shelf)




(focuser with 1.25" eyepiece attached via 2"/1.25" reduction - included)




(accessories included: 2" / 2" 35mm extender, 30mm / 2" eyepiece, 9mm / 1.25" eyepiece, fan power supply, 2" / 1.25" adapter)




(ball bearing in azimuth axis)




(change of tube position in the azimuth axis - i.e. "left - right")




(changing the position of the tube in the height axis - i.e. "top - bottom")

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

Answer: Pyrex is the trade name for borosilicate offered by Corning. Many companies offer glass with the same composition and parameters, but often the proper name Pyrex is used to describe borosilicate glass (a bit like sports shoes are called Adidas). A characteristic feature is that this glass has a thermal expansion coefficient that is about three times smaller.

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

BK-7 is a decent optical glass, commonly used also in the best optical systems. It is not bad glass, as is sometimes believed. What is more, from the point of view of the user of a Newtonian telescope, the optical characteristics of the glass are irrelevant - the important element is the figure 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 reflective layer.

To answer briefly:
• no, GSO telescope mirrors 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 is no difference in the images obtained between Pyrex and BK-7
• BaK-4 is a rather expensive optical glass with a high refractive index, used practically exclusively in prisms (telescopes, binoculars, in angle connectors with Amici prisms, etc.), of little use and rarely used in lenses and eyepieces
• the presence of active cooling ("fan") at the back of the mirror shortens the cooling time of the mirror to 15 - 30 minutes, thus eliminating the difference between BK-7 and Pyrex.