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Telescopes > Orion > Astrograph > Orion Telescope N 203/790 Astrograph OTA
Product no.: 25385

Telescope N 203/790 Astrograph OTA

$ 710.00 incl. VAT, plus shipping costs
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Product description

A Newtonian astrograph optimized for astrophotography at an affordable price!

With its relatively large aperture and fast aperture ratio of f/3.9, this low-cost reflector approaches the performance of expensive apochromats.

The large secondary mirror fully illuminates CCD and DSLR sensors. The image contrast is enhanced by nine baffle rings built in the tube - these will intercept any stray light. Also for this reason, the opening at the back of the OTA is well forward of the 2" dual-speed Crayford focuser and, finally, a matte black finish further increases contrast.

Both the primary and secondary mirrors are coated with highly reflective aluminium (94%) over which a protective layer of quartz has been added. The built-in fan ensures fast cool-down of the primary mirror.

This astrophotography Newtonian can also be used visually using 1.25" or 2" eyepieces thanks to an extension 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.
  • We also provide an edition of the exciting astronomy magazine, “Sterne und Weltraum” with each telescope.

Specifications

Optics


Type
Reflector
Type of build
Newton
Aperture (mm)
203
Focal length (mm)
790
Aperture ratio (f/)
3,9
Resolving capacity
0,57
Limit value (mag)
13,3
Light gathering capacity
840
Max. useful magnification
406
Tube weight (kg)
8
Tube construction
Full tube
Tube length (mm)
762
Tube material
Steel

Reflector


Main mirror´s construction
parabolic
secondary mirror design
Plan
Ventilation for central mirror
yes
Adjustable
yes
reflectivity
94
aluminising
Aluminium
protective layer
Quartz
secondary mirror spider legs (piece)
4
Primary mirror - Material
Borosilicate glass
Secondary mirror diameter (mm)
70
Secondary mirror obstruction
35

Focuser


Type of build
Crayford
Connection ( to eyepiece)
2
Backfocus (mm)
69
Gear reduction
1:11 fine focusing

Mount


Mounting type
no mount
Type of build
OTA
GoTo control
no

Included accessories


Finder scope
9x50
Collimation aid
Collimation cap
Eyepiece adaptor
1,25" - 2"
Tube clamps
yes

General


Series
Astrograph

Area of application


Moon & Planets
yes
Nebulae & galaxies
yes
Nature Observation
no
Astrophotography
yes
Sun
no (Only with appropriate Sun filter)

Recommended for


Beginners
no
Advanced
yes
Observatories
no

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*All prices include VAT plus shipping costs.

Orion Telescope N 203/790 Astrograph OTA

Inside the OTA: the anti-reflection baffles ensure especially good contrast for astrophotography

Orion Telescope N 203/790 Astrograph OTA

The mirror cools down faster using the fan

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