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Opticstar ARC90 Optical Tube Assembly (OTA)
Entry Level Refractor
To order this item outside mainland Britain or Highlands, please contact us.
Opticstar ARC90 Optical Tube Assembly
Opticstar ARC90 Optical Tube Assembly (OTA).
  • 90mm Refractor
  • Focal length: 900mm
  • Focal ratio: F/10
  • 6x30mm Finder scope
  • Mounting bracket with dovetail bar
  • 25mm eyepiece (1.25")
  • Star Diagonal (1.25")
Opticstar Visual
Opticstar Mount
CCD Cameras
Opticstar ARC90 Optical Tube Assembly (OTA)
Package includes:
  • Opticstar ARC90 refractor optical tube assembly.
  • Mounting bracket with dovetail bar
  • 6x30mm Finder Scope.
  • 1.25" 25mm Eyepieces.
  • 1.25" Star Diagonal.
  • Free options (please select one):
    • FREE: Opticstar 1.25" Moon Filter with 25% light transmission. Reduces the glare of the Moon. (R.R.P.: £9.95).
    • FREE: Red LED Torch made of aluminium alloy. Helps to preserve your night vision. (R.R.P.: £9.95).
  • OFFER: Please refer to the right hand column on this page.
Order No. Price (inc_VAT) Shipping Delivery click button to purchase
OSRA9L £ £
Opticstar ARC90
User Manual (PDF)
Opticstar CCD Cameras

The Opticstar ARC-90 is a 90mm aperture F/10 achromatic refractor that is ideal for planetary, Lunar and Solar observing with an appropriate Solar filter. The ARC-90 uses an air-spaced achromatic doublet delivering high magnifications for its aperture. The scope can also be used for high power terrestrial observation with an optional prism diagonal.

Optical Design
The ARC-90 uses an anti-reflection coated doublet objective lens for increased image contrast and sharpness. The long focal ratio restrains chromatic and other optical aberrations making the telescope well suited for observation at higher powers.

Opticstar ARC90 Optical Tube Assembly

The optical tube has been internally anti-reflection coated and benefits from knife-edge baffles that prevent stray light from reaching the focal plane thus increasing image contrast and sharpness. To further increase image quality, the optical tube assembly has a dew shield that also protects the lenses from condensation forming on the objective when the telescope is used in unfavourable conditions.

The telescope's rack & pinion focuser will accept standard 1.25" astronomical accessories including diagonals, eyepieces, barlows etc. The telescope has a Vixen/Sky-Watcher type dovetail and will mount on most astronomical mounts including the Opticstar EQ700 and EQ1300 GOTO (coming soon).

The ARC-90 comes with a 6x30mm finder scope and bracket, 1.25" star diagonal, and a 25mm eyepiece. A Moon filter and additional eyepieces are optional. A 25% transparency Moon filter is recommended as is a 5mm-6mm eyepiece for high power viewing.

Bundled accessories.
Bundled accessories.
Model Opticstar ARC90
Aperture 90mm
Focal ratio F/10
Focal length 900mm
Objective Achromatic doublet
Optical coatings Anti-reflection coated
Optical tube Internally anti-reflection coated, knife-edge baffles
Dew shield Yes
Finderscope support Yes
Focuser Rack & Pinion
Focuser adapter Accepts 1.25" eyepieces and star diagonals
Tube rings Single wide tube ring with dovetail platform
Tube weight 2.6kg (inc. ring/dovetail)
Tube length 910mm
Eyepieces 1.25" 10mm & 1.25" 25mm
Magnification With bundled eyepiece:
  • w/25mm eyepiece x36

With optional barlow lens and/or eyepieces:
  • w/25mm eyepiece and x2 barlow lens x72
  • w/9mm eyepiece x100
  • w/6mm eyepiece x150
Star diagonal 1.25"; 90°
Finderscope 6x30mm with bracket

Opticstar ARC Series Refractor Optical Tube Assemblies
Model Aperture Focal Ratio Focal Length Optical
User Manual
Opticstar ARC90 Optical Tube Assembly ARC90 90mm F/10 900mm Achromatic doublet ARC90 OTA (PDF)
Opticstar ARC102S Optical Tube Assembly ARC102S 102mm F/6.6 673mm Achromatic doublet ARC102S OTA (PDF)
Opticstar ARC102 Optical Tube Assembly ARC102 102mm F/9.8 1,000mm Achromatic doublet ARC102 OTA (PDF)
Opticstar ARC127 Optical Tube Assembly ARC127 127mm F/9.5 1,200mm Achromatic doublet ARC127 OTA (PDF)
Opticstar ARC152 Optical Tube Assembly ARC152 152mm F/7.9 1,200mm Achromatic doublet ARC152 OTA (PDF)
Opticstar ARC Series Refractor Optical Tube Assemblies

Opticstar ARC QUAD Series Astrograph Refractor Optical Tube Assemblies
Model Aperture Focal Ratio Focal Length Optical
User Manual
Opticstar ARC127 Optical Tube Assembly ARC127 QUAD 127mm F/4.9 622mm Achromatic quadruplet ARC127 QUAD OTA (PDF)
Opticstar ARC152 Optical Tube Assembly ARC152 QUAD 152mm F/5 760mm Achromatic quadruplet ARC152 QUAD OTA (PDF)
Opticstar ARC QUAD Series Astrograph Refractor Optical Tube Assemblies

We are constantly checking the accuracy of the technical data. We are prepared to provide more detailed information on request. Technical data is subject to change without notice.

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Promotional Offer
Cash Back on Opticstar
Imaging Products
updated: 8th September 2017
Opticstar cashback offer.

Customers who purchase any Opticstar telescopes, Opticstar optical tubes or Opticstar mounts listed on this page qualify for a 10% cash back on any Opticstar astronomy cameras purchased at the same time or at a later date.

This offer is valid for 1 year commencing on the date that the Opticstar product is purchased from the Opticstar website or the Opticstar showroom.

Any additional purchases at a later date of Opticstar products that qualify for this offer will renew the cash back period to 1 full year.

Opticstar astronomy cameras that qualify for this offer include the following: Once an Opticstar CCD or CMOS camera has been purchased within a year of the qualifying Opticstar purchase, the cash back can be claimed by contacting Opticstar by email or over the phone quoting the receipt number(s). Please allow up to 14 days to process the payment.

Sample Images
Opticstar DS-145M ICE
posted: 13th March 2009
Sample image.
The NGC7293 shot by John Haunton with the Opticstar DS-145M ICE.
We want to hear your comments.
Sample Images
Opticstar DS-335C ICE
updated: 20th August 2010
Sample image.
The Trifid nebula shot by John Haunton with the Opticstar DS-335C ICE.
Opticstar Imaging
posted: 26th February 2013
Opticstar telescopes for imaging.
High quality refractor telescopes, bundled with CCD cameras for deepd sky imaging, planetary video imaging and auto-guiding.
A&M 80mm f/6 Review
"Best Of Breed"
updated: 25th March 2009
A&M 80mm f/6 A&M/TMB.
The A&M 80mm f/6 A&M/TMB has been reviewed in Cloudy Nights and it has been hailed as the "best of breed". The review concludes by saying "offers stunning performance while standing out from the crowd, look no further".
Willmann Bell
Books for Astronomy
updated: 20th September 2019
Willman Bell books.
Acclaimed books from Willmann Bell...
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