SHARPSTAR AL-140PH APO TRIPLET F/6.5
The Sharpstar AL-140PH APO is an apochromatic triplet with a focal ratio of f/6.5 and a focal length of 910mm. The objective lens includes two Extra Low Dispersion glass for a superb chromatic correction.
The large rack and pinion 4" focuser can be rotated 360°and it has a reduction gear of 1:10 for precise focusing. This refractor works at its best when used with the SharpStar 2.5" field flattener for superior performance in astrophotography.
All the lenses are fully multi-coated and the tube is internally flocked to reduce reflections and absorb stray light. The tube is made of aluminium, the rack and pinion focusing mechanism of brass and the mechanical components are engineered to provide the best rigidity, performance and durability.
Every SharpStar telescope is inspected on the optical bench by Testar and guaranteed against defects. To ensure optimal performance, every telescope undertakes the following tests:
- Star test in autocollimation by using a Zerodur λ/20 mirror to revel tensioned optics or optical aberrations
- Collimation test using a GMK collimator
- Ronchi test to evaluate the overall correction of the lenses.
Chromatic aberration diagram
| Optical design |
Apochromatic triplet dual ED air spaced |
|
Objective diameter |
140 mm |
|
Focal length |
910 mm |
|
Focal ratio |
f/6.5 |
|
Resolving power |
0.86 arc second |
|
Stellar limiting magnitude |
12.7 |
|
Max. magnification |
280 x |
|
Light gathering power |
400 times the human eye |
|
Mount attachment |
Losmandy style bar |
|
Focuser |
Rack & pinion dual speed (10:1) 4" diameter |
|
Camera connection |
M78x1 female / M74x1 male / M68x1 female |
|
Backfocus |
TBA |
|
Tube weight |
11.7 kg (including tube rings and dovetail bar) |
|
Tube length |
876 mm (738 mm with retracted dew shield) |
|
Tube diameter |
148 mm |
|
Dew shield diameter |
179 mm |
|
SKU |
SS-AL-140ED |
- SharpStar AL-140ED f/6.67
- 148mm tube rings
- Losmandy style dovetail bar
- Adapter to 2" and 1.25"
- Foam-lined aluminium case