An inexpensive and yet high-quality access into the 200 mm scope range!
This Dobsonian typically stands for high optical performance at a low price. Its cost/performance ratio is truly unbeatable. In terms of optical quality, tube mechanics and finishing, there has been no compromising.
Observing nebulae and galaxies:
The 200 mm aperture reveals structures in planetary nebulae and first signs of spiral arms in galaxies. Wider nebula structures, such as the Cirrus Nebula in Cygnus, are shown with already a certain amount of detail.
Lunar and planetary observation:
This is an area in which the Dobsonian delivers most extraordinary results. The tiny secondary mirror and its ultra thin supports ensure excellent contrast and sharpness. That's exactly where the high optical quality of the mirror comes to bear.
Easy mounting - and off you go …:
The easy handling of this Dobsonian makes it a good choice for the newcomer. You just put the rockerbox -which is the lower part of the unit- into place. Then you hook the scope with its height adjustment wheels into the hinge and you tension the springs. The scope is ready for observation.
Working with the Dobsonian mount:
The mount of the Dobsonian scope is also called rockerbox. It supports the tube and enables you to aim at the objects you wish to observe. Adjustment is easy, similar to a photo tripod. For horizontal control, you simply rotate two circular plates located on the base relative to each other. Vertical control is achieved via the two height adjustment wheels. The teflon bearings ensure smooth controlling, and it will only take you a minimum of experience to be able to track objects precisely, including at the highest level of reasonable magnification.
Thin secondary mirror supports:
Contrast is enhanced because diffraction is reduced. And high contrast is important, especially for lunar and planetary observation.
Solid 2" Crayford type eyepiece holder:
The solid 2’’ Crayford type eyepiece holder is an enhancement of existing eyepiece holders. It is firmly seated in a compact housing which provides a high level of stiffness. The ball bearing and the Crayford structure ensure very smooth adjustment with absolutely no image shifting. The device is locked with a brass ring.
Pretensioning the spring:
This avoids unintentional adjustment alterations during eyepiece changes.
Cooling speed:
The primary mirror support must be of some homogeneous material, in order to avoid any twisting. Using high levels of magnification during the cooling process is not recommended, not only because the mirror dissipates heat but also because it first needs to take its shape. With this Dobsonian, active primary mirror cooling brings adaptation time down to approximately 30 min. At that stage, the support material (homogeneous BK-7) has reached its curve and the only thing which then determines the quality of images is the precision of the mirror surface.
The support material for this mirror is BK-7. In terms of twisting, homogeneity, etc., it does not fall short of others like pyrex or suprax in any way; this material too, is produced and checked with great care. It's only during the cooling phase of approximately half an hour that you should not push the scope to maximum magnification.
This Dobsonian doesn't leave you stuck there :
A Dobsonian scope only offers limited possibilities for astrophotography. Without a tracking device, pictures can be taken only of the brightest objects (the Sun - with an adequate filter, the Moon and the planets). For longer exposure times and higher resolution, we recommend a parallactic mount which will also support the unit.For this Dobsonian, we provide optional clamps which will enable you, in the future, to fit a parallactic mount without any problems.
Dobson telescopes are the most useful instruments in the astronomy.
Their construction is rather simple but genuine. In general, they consist of two main parts. The first one is the optics, the second is the mount which consists of a wooden box on the floor which allows the optical tube assembly to pivot in altitude, while the box itself is swivelled on a base in azimuth. You just have to insert the tube and you can immediately start your observation and don´t have to install and focus the mount first.
The basic idea concerning the construction of a Dobson telescope was that a large telescope optic should be available for low budget. And this was successful! Since the invention of the Dobson telescope, the fan club has been growing and growing. These people are fascinated by these instruments and their fascinating simplicity. Motto: Real Power for low budget!
The optics of this Dobson has a diameter of 20cm (8“) and a focal length of 1200mm. Thus, the common aperture ratio of 1:6 is reached. An optic like this provides a very strong light collecting ability (816x). When the sky is rather dark, you can observe stars of marginal sizes of 14mag. Especially in case of apertures of 200mm, you can get best results for Deep Sky objects, what is not really possible with smaller telescopes. The secondary mirror rods are very thin and thus, the diffraction is very low. The optic`s obstruction is about 25% because of the secondary mirror!s diameter (about 50 mm).
The rocker box the telescope is mounted on is easy to handle. The telescope can thus be moved easily and with only a few fingers in azimuth and and height The telescope can be moved with floating and pivot bearing.The optic stays stable in every position to allow a beautiful and undisturbed sky observation.Even if you want to magnify intensely, the observation will be pure fun!
With the new Tension Control System, you can adjust easily on the rocker box if the optics should be rough-running or smooth-running. Consequently, you always have the fitting resistance.
The2“ eye piece pullout is smooth-running and equipped with a reduction jacket of 1,25“.
By the help of the9x50mm finder scope with a fine reticule, it´s easy to find even faint objects.
The new parabolic reflectors of this DOBSON-PX range are made of Pyrex. The Pyrex reflector bracket is not as vast as for example the common BK7 glass material. The dimension of BK7 is about 2x larger than with a Pyrex. This mirror can not easily be drafted. Thus, it remains in its geometric form even during the cooling time, and this is the difference to a reflector made of BK7 glass. Because of this, the mirror provides a better reproduction efficiency in the cooling down phase. Moreover, Pyrex can be parabolised much easier. However, this mirror doesn´t cool down in a shorter period of time than other mirror products.
The mirrors are 75nm p.t.v. minimum or even better. Thus, the requirement for high definition and precision, Lamda/8, is fulfilled.
Dobson Telescopes are equipped with a Strehl value of 0,8 or higher. This tells us about the optical efficiency and power of this telescope: If 80% of the light unite in the telescope´s diffraction slices, astronomers call this a “diffraction limited optics”. This means that the resolution of a telescope is only limited by the light´s diffraction. As this chiffre can not be 100%, the definition of the diffraction limit has been fixed on 0,8. Thus, you have a recommendable optics (other system related losses are not considered here)
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