Tecnosky 210mm F5.9 Doublet Achromat 3" Focuser

Tecnosky has developed a large 210mm (204mm Clear Aperture) short-focus achromatic refractor for wide field deep-sky observation and photography in narrow band, including solar.

The lens is composed of an air spaced doublet with multi-layer anti-reflection coatings; the lenses are housed in an aluminum collimatable cell. The tube is made in Italy, from anti-corroding 3mm aluminum and is fitted with internal baffles. The focuser is a smooth 2.7" from Tecnosky.

The tube is different in not having tube rings. Instead, it uses two strong (but lighter) crescents linked to a long bar Geoptik Losmandy. The total weight of the instrument is only 17kg.

Testing has confirmed a good overall optical correction for such a low F ratio Achromat with a very good manageable chromaticism of the Moon and planets using a Baader Semi Apo filter. Despite being a telescope for use at medium / low magnification of deep-sky objects, detailed close up views of solar system objects are quite possible.

Due to its low focal ratio the 210 is also well suited to imaging of Narrowband Deep Sky objects.

The 210 is also very suitable for use as a giant H-alpha telescope, using rear mounted filters from PST etalons upwards. An example image using a PST taking with the scope is shown above. To aid Solar use, we can provide an internally mounted 75mm Baader D-ERF with integral cell designed to be mounted directly on the front of the focuser. A front mounted, 235mm ERF filter is also planned. Please contact use for details about this.

As this is essentially a custom made product we can also offer various focuser options. On request the scope is also available as an 1800mm focal length version. Please ask for pricing about custom options.

Please note that as this is a custom made scope there is a short lead time to allow for tube manufacture.

Specification

Optics 210mm (204mm clear aperture) Focal 1200mm F / 6 Surface Accuracy: (not worse) 1/4 lambda at 632nm Surface Quality: (not worse) 40-60 scratch and dig Intubation aluminum Focuser Titanium Tecnosky 2.7 "