Telescope N 250/950 AG10 Carbon Astrograph OTA

Astrographs from Orion Optics UK: Light-gathering high-end astrograph with 4-element Wynne corrector for ultimate astrophotography!

A key to the success of these astrographs is the carbon fibre tube. This lightweight material puts less strain on the mount than an aluminium tube and maintains focus during long exposure times, as carbon is very temperature stable.

All AG telescopes are extensively tested in the optical laboratories of Orion, UK. To prevent stray light from entering through the edge of the primary mirror, it is covered by a baffle, resulting in razor-sharp images of the stars – unmatched quality.

Some other special features of AG telescopes from Orion Optics UK:

• All Orion UK AG primary mirrors are made from SCHOTT Suprax borosilicate glass ( virtually identical to Pyrex) with low thermal expansion, as are the primary mirrors of all this manufacturer's telescope ranges. All mirrors are manufactured to high specifications as rotationally symmetrical paraboloids with an aperture ratio of 1:4. How accurate are they? The glass is only sent for mirror coating once it has achieved a surface accuracy of 1/16 wavelength or better. This high degree of accuracy is checked using a Zygo laser interferometer.
• The elliptical secondary mirrors are also manufactured to the highest standards and tested with the Zygo. For larger versions, Orion uses Suprax to achieve stability and accuracy. These are then Hilux-coated together with the primary mirrors, ensuring the highest reflective aluminium coatings with a protected surface available anywhere.
• The mirror cell: Orion UK chose the current design after extensive computer calculations and testing. A 9-point system with nylon 66 tips distributes the load of the mirror as evenly as possible across 9 points on the back of the mirror. The cells are CNC-milled and then carefully finished by hand to eliminate even the smallest errors. They are then anodised to not only provide the aluminium with a corrosion-resistant coating, but also to harden the surface against scratches and wear.
• The main mirror cell is equipped with a fan that is powered by 12 volts DC, significantly reducing the risk of fogging and quickly adjusting the mirror to the ambient temperature.
• The simple and robust collimation system ensures that the mirror always remains in exactly the same collimated position. Its robustness also ensures a constant focal point, even after months of use in observatories.
• The ACU-3L focuser: To further improve the quality and performance of the AG series, Orion has introduced a completely new model of its focusers, the ACU-3L. It has a long focuser tube with a diameter of 3" (76.2 mm) and is threaded for both Orion's highly acclaimed 3" Wynne corrector and other accessories. These are not simply inserted, but screwed in place using a fine thread. Basic focusing is achieved using silky-smooth main focus knobs, after which, if perfect focusing is required, the fine adjustment knob takes over with a very smooth movement at a 10:1 reduction ratio. The extension tube slides with slow, very smooth and precise movement.
• Wynne corrector: The design of the AG corrector was finalised after months of calculations and field tests with different cameras and telescopes. It is not only used in the AG models, but also works incredibly well with telescopes from other manufacturers with different mirror sizes and aperture ratios. The corrector, which reduces the image to 0.95 times its size, consists of four elements made of special glass, arranged in two individual lenses and a cemented doublet. This focuses the light from the telescope onto a flat image plane with a diameter of 60 mm, without any colour aberrations. The design is based on the use of several rare earth glasses and the computer-assisted selection of the curvature radii of the lenses. Thanks to the complex construction, even world-renowned astrophotographers can no longer find any errors in the images.
• Adapting your camera to the M85 thread: The Wynne corrector has an M85x1 external thread on the camera side, and a 2" adaptor is included in the scope.
• Tube clamps: To ensure maximum safety and accuracy, Orion Optics UK manufactures tube clamps from solid aluminium pieces on its own CNC milling machines. These are then black anodised to protect the surfaces, which are lined with felt to ensure a gentle but firm hold on the polished tubes. The large knurled knob on each tube clamp adjusts the pressure to achieve a precisely defined friction on the outside of the tube.

It not only matters which telescope you buy but also where you buy it. Our additional services:

• We are a leading telescope dealer and know the devices we sell. Our customer service team will gladly help you after your purchase if you have problems with assembly or operation.
• We provide a copy of the 80-page Telescope ABC beginners handbook with every telescope.