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Ascension 127ED Triplet APO Premium
Premium Quality - Triplet Apochromat Refractor
To order this item outside mainland Britain or Highlands & Islands, please contact us.
Ascension 127ED Triplet APO
Ascension 127ED Triplet optical tube with dewshield retracted.

  • Japanese Triplet FCD1 ED objective
  • Strehl Ratio: 0.90 or better
  • Lens diameter: 127mm
  • Focal ratio: F/7.5
  • Fully (broadband) multi-coated lenses
  • Precision dual-speed (11:1) focuser
  • Retractable Dewshield (with aluminium cap)
  • Dovetail
  • Diffraction limited optics
Telescopes Sky-Watcher
Sky-Watcher Mount
Ascension 127ED Triplet APO OTA Premium
Package includes:
  • Ascension 127mm f/7.5 FCD1 ED Triplet optical tube assembly (OTA).
  • Strehl Ratio: 0.90 or better.
  • Interferometer test report for the individual instrument.
  • 2" Dual Speed Rack & Pinion (11:1) focuser.
  • Dovetail and brackets.
  • Two extension tubes.
Optional Accessories
Opticstar 2" Deluxe Dielectric Diagonal. + £69.00
Opticstar 8x50mm Illuminated Finder Scope. + £49.00
Ascension Field Flattener for imaging. + £99.00
Order No. Price (inc_VAT) Shipping Delivery click button to purchase
ASC127ED3E £ 995.00 £ 10.00
Ascension User Manual

High contrast and minimal colour aberrations are both highly desirable features in a modern telescope. Triplet lens designs incorporating exotic glasses present optical systems practically free of chromatic aberration (colour fringing) and capable of pin-point star images.

The Ascension APO (apochromatic) refractors use a high quality triplet lens objective made of premium Japanese ED (Extremely Low Dispersion) glass to achieve images of high contrast and virtually free of secondary colour. Fully (broadband) multicoated lenses ensure maximum light transmission.

Objective lens.
Apochromatic triplet objective lens.

Designed with wide field observing and imaging in mind these triplet apochromatic telescopes offer an array of features including a versatile mounting system, precision 2-speed Rack & Pinion focuser and retractable dew shield.

Ascension 127ED Triplet APO
The Rack & Pinion dual speed (11:1) focuser.

Optical Performance
The new Ascension ED Triplet Premium refractors guarantee an RMS of 0.052 (0.90 Strehl) or better clearly outperforming diffraction-limited (RMS 0.071, Strehl 0.82) apochromatic ED refractors.

The Ascension ED Triplet Premium Plus models guarantee an RMS of 0.047 (0.92 Strehl) or better.

In addition the High Precision (HP) range guarantees an even higher RMS of 0.36 (0.95 Strehl) or better offering unmatched value for money and excellent performance.

In imaging terms the high quality FCD-1 objective ED triplet will bring the image in sharp focus when imaging unlike apochromatic ED refractors that rely on a doublet ED objective for imaging.

RMS Rating Strehl Ratio Comments Note
0.094 0.710 . not diffraction limited
0.071 0.820 Rayleigh Limit (diffraction limited) good
0.057 0.880 . .
0.052 0.900 Ascension ED Triplet - Premium very good
0.047 0.920 Ascension ED Triplet - Premium Plus very good
0.041 0.940 Ascension ED Triplet - Premium Plus very good
0.036 0.950 Ascension ED Triplet - High Precision excellent
0.032 0.960 Ascension ED Triplet - High Precision excellent
0.028 0.969 Ascension ED Triplet - High Precision excellent
Ascension High Precision optics are subject to availability from the manufacturer.
The Strehl Ratio is calculated from the RMS rating value: Strehl ratio = 1 - (2π x RMS Rating)2

The optical tube greatly benefits from metal knife-edge baffles that prevent light which has bypassed the optical system or which is outside the field of view from reaching the focal plane thus increasing image contrast.

At f/7.5 (127mm) the focal ratio of the Ascension 127ED Triplet is well suited for wide field astrophotography.

Ascension 127ED Triplet APO
The Ascension 127ED Triplet with the dewshield extended. Shown with optional finder scope and 2" dielectric diagonal.

The telescope comes with a high quality rotatable CNC machined 2" hybrid Rack & Pinion focuser with a very high load capacity. This 11:1 dual speed focuser is very smooth to operate, thus making focusing accurate and precise.

The focuser comes with a 2" to 1.25" adapter, both 2" and 1.25" drawtubes have copper rings to better secure attached accessories including diagonals, eyepieces, cameras, filter-wheels etc.

This improved design incorporates a central hand-operated locking mechanism and two hand-operated pressure mechanisms on either side of the focuser to increase the pressure by spreading the load as required.

Ascension Specification Comparison Chart
Specification Ascension 80ED Triplet - Essential Ascension
102ED Triplet - Essential
127ED Triplet - Essential
Optics ED Triplet ED Triplet ED Triplet
Coatings Fully-multicoated Fully-multicoated Fully-multicoated
Aperture 80mm 102mm 127mm
Focal Length 480mm 714mm 952.5mm
Focal Ratio f/6 f/7 f/7.5
Focuser Type 2-speed Rack & Pinion (11:1) 2-speed Rack & Pinion (11:1) 2-speed Rack & Pinion (11:1)
Focuser Drawtube 2" with 1.25" adapter 2" with 1.25" adapter 2" with 1.25" adapter
Focuser Design Rotatble Rotatble Rotatble
Focus Travel 12cm 12cm 12cm
Baffles Knife-edge Knife-edge Knife-edge
Tube (LxWxH) 38x9x9cm 59x13x13cm 85x16x16cm
Length with extended dew-shield 48cm 74cm 106.5cm
Focuser assembly width 15cm 15cm 15cm
Weight w/supplied rings & dovetail -- 5kg 7.5kg
Weight w/supplied rings -- -- --
Weight w/ 1/4" tripod support -- -- --
Weight w/ dovetail 2.75kg -- --
Finder scope and bracket optional optional optional
Star diagonal & 1.25" adapter optional optional optional
Eyepiece optional optional optional

Also available the Ascension 102ED Triplet APO - Bundle
The Ascension 127ED Triplet APO is also available with a full complement of accessories as shown below.

Ascension 127ED Triplet APO
The Ascension 127ED Triplet Bundle includes two wide angle eyepieces, two extension tubes, illuminated finder scope,
dielectric diagonal and aluminium case (not shown) and interferometer test report.

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.

How To Order Terms & Conditions Email Us
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Promotional Offer
Cash Back on Opticstar
Imaging Products
updated: 1st August 2017
Opticstar cashback offer.

Customers who purchase any Ascension telescopes or Ascension optical tubes 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 Ascension product is purchased from the Opticstar website or the Opticstar showroom.

Any additional purchases at a later date of Ascension 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 Ascension 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 M20 nebula 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 M42 nebula shot by Nick Witte Vermeulen 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...
Opticstar News
New DS-616C XL+ Model
posted: 24th August 2017
Opticstar DS-616C XL+.
Star product, improved.

The new Opticstar DS-616C XL+ deep-sky CCD is the successor to the popular DS-616C XL that earned the annual star product award back in 2013. It maintains all the features of the original model as well as other improvements.

DS-616C XL is Astronomy Magazine's Star Product
posted: 12th September 2013
Opticstar DS-616C XL is Astronomy magazine's product of the year.
Star product.

The Opticstar DS-616C XL deep-sky CCD camera has earned the annual star product award from Astronomy, the world's best-selling astronomy magazine. Read about it in the September 2013 issue.

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