Glossary | Telescopes | General | Series | T500

In the T500 series, the high-quality Dobsonian telescope of truss-tube construction comes with a 20'' (504mm) parabolic primary mirror. From this size upwards, there is almost no limit to what you can observe, and you can view the sky with up to 500 times magnification. It delivers such fascinating and detailed images of galaxy arms, nebulae or star clusters, that you won't be able to look away. The complete construction weighs just 44kg and fits folded in the boot of any car. The T500 comes in a standard and professional version.

Dobsonian telescopes may all look the same externally, but have different features. These features are identifiable in the product title:

• Secondary mirror heating (SMH): this is a small heater with a temperature sensor that prevents dew from collecting on the exposed secondary mirror. Requires batteries or a power bank.
• CF (cooling fan): fans located behind the primary mirror for faster temperature adaptation. Actually only useful for the large Dobsonian models. Requires batteries or a power bank.
• DSC (digital setting circles): encoders in altitude and azimuth axes. They display the position of the axes, allowing you to use smartphone apps to orient yourself in the sky. They connect to the smartphone via Bluetooth.

Simply watch out for these abbreviations in the product title to find your perfect telescope.

You can also choose between two colours: black or dark oak.

The telescopes in this series are available with two different primary mirrors:

• STANDARD: The primary mirror is made of borosilicate glass, with 93% aluminium coating and a quartz protective layer. Accuracy is 1/4 Lambda (peak to valley) or 1/16 RMS. Borosilicate glass is used in laboratories, but also in the kitchen, as it is chemically highly resistant. These mirrors are absolutely sufficient for occasional observing from city locations, especially if you prefer bright objects such as the Moon and planets.
• PROFESSIONAL: The primary mirror consists of SUPREMAX-33 glass from SCHOTT, with 96% aluminium coating, a quartz protective layer, and is supplied with a test record. Accuracy is 1/8 Lambda (peak to valley) or 1/40 RMS. SUPREMAX glass has very low thermal expansion, so it remains dimensionally stable when the temperature changes. Those who like to take their Dobsonian to a dark sky locations to hunt for Messier and NGC catalogue objects will benefit from this high quality.

Look out for this designation in the product title to find your perfect telescope from the wide selection available.