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
|
Features
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.
