Opticstar/Ascension 102ED Triplet APO Premium Plus (marks)

Premium triplet APO offers fully multi-coated optics and sharp images.

  • 3-element premium Japanese FCD1 glass
  • Optical Coatings: Fully Multi Coated
  • Strehl Ratio 0.92 or better
  • Interferometer report included
  • Diffraction limited optics
  • Aperture: 102mm
  • Focal Length: 714mm (f/7)
  • 2" Dual-Speed Rack & Pinion Focuser
  • 2" Dielectric Diagonal (99%+ reflectivity)
  • 8x50mm wireless illuminated finderscope
  • Two (2) Wide Angle 70° eyepieces (FMC)
  • Retractable Dewshield
  • FREE: accessories (see below)
  • UK warranty
Opticstar/Ascension 102ED Triplet APO Premium Plus (marks)
  • Product code: 102ED3D
  • Availability: In stock
  • Despatch: 2 business days
  • Retail Price: £ 1250.00
Shipping rates
England & Wales
£ 20.00
Scotland Central & South
£ 20.00
Scotland North
£ 40.00
Northern Ireland
£ 40.00
UK islands (from)
£ 40.00
European Union (from)
£ 30.00
Worldwide (from)
£ 80.00

Free accessories included (limited offer)


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. An interferometer report with each individual telescope is provided.

The Opticstar/Ascension APO (apochromatic) refractors use a high quality made 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.

Note: The optical tube of this telescope has some minor cosmetic marks.


The telescope comes complete with the following accessories:

  • 8x50mm wireless finder with adjustable illuminated reticle.
  • 2-inch dielectric diagonal (over 99% reflectivity) with 1.25" eyepiece adapter.
  • Wide Angle 10mm 70° fully multi-coated eyepiece.
  • Wide Angle 20mm 70° fully multi-coated eyepiece.
  • Bracket for 50mm aperture finderscopes.
  • Dovetail & mounting rings with carry-handle.
  • Sturdy Aluminium case.





▼ read more ▼

Optical performance

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 (11:1) Rack & Pinion focuser and removable dew shield.

The Opticstar/Ascension ED Triplet Premium Plus refractors guarantee an RMS of 0.047 (0.92 Strehl) or better clearly outperforming diffraction-limited (RMS 0.071, Strehl 0.82) apochromatic ED refractors.

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
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 (102mm) the focal ratio of the Opticstar/Ascension 102ED Triplet is well suited for wide field astrophotography.

Carries full one year UK warranty.

▲ read less ▲
▼ show specification ▼
Opticstar/Ascension 102ED Triplet APO Premium Plus (marks)
Attribute Specification
Opticstar Product Code / sku 102ED3D
Universal Product Code (UPC) n/a
Warranty 1 year UK warranty
Series Ascension APO
Experience Level Advanced
Clear Aperture 102mm
Focal Length 714mm
Focal Ratio f/7
Optical Design Apochromatic Refractor
Optical Elements 3-elements
Optical Glass Japanese FCD-1 Premium ED (extremely low dispersion)
Strehl Ratio 0.92 or better
Optical Coatings Fully (Broadband) Multi-Coated
Focuser 2-speed Rack & Pinion (11:1)
Focuser Drawtube 2-inch with 1.25-inch adapter
Focuser Design Rotatable
Focus Travel 12cm
Baffles Knife-edge
Dew Shield Fully extendable dew shield with aluminium cap
Dovetail Vixen-style
Interferometer Report Included with each invidvidual telescope
Finderscope Bracket Included (bracket for 50mm aperture finderscopes)
Hard Case Sturdy aluminium case
Eyepieces Two (2) high quality 10mm & 20mm 70° wide angle fully multicoated eyepieces
Diagonal 2" dielectric diagonal (over 99% reflectivity) with 1.25" eyepiece adapter
Viewfinder 8x50mm wireless finder with adjustable illuminated reticle
Field Flattener Not included
Assembled Product Weight 5 kg (w/supplied rings & dovetail)
Assembled Product Dimensions 59cm x 13cm x 13cm
Length with Extended Dew-shield 74cm
Transit Weight 12 kg
Transit Dimensions 72cm x 41cm x 30cm
▲ hide specification ▲
Dedicated accessories
  • Product code: FLDFLT
  • Availability: In stock
  • Despatch: 2 business days
Similar telescopes
  • Product code: 102ED3E
  • Availability: In stock
  • Despatch: 2 business days
  • Product code: 102ED3F
  • Availability: In stock
  • Despatch: 2 business days
  • Product code: 102ED3B
  • Availability: In stock
  • Despatch: 2 business days
  • Product code: 102ED3C
  • Availability: In stock
  • Despatch: 2 business days
0.1 MB • 12 October 2021
0.2 MB • 12 October 2021