Sky-Watcher SKU: S11520 | Helix SKU: CTS11520
| SKU | S11520 |
| UPC | 050234115209 |
| Optical Info | |
|---|---|
| Optical Design | Mak-Cass |
| Mirror Coatings | 94% Aluminum |
| Lens Coatings | Fully Multi-Coated |
| Glass Type | BK7/Borosilicate |
| Primary Aperture (mm) | 127 |
| F/Ratio | 12.1 |
| Focal Length (mm) | 1540 |
| Secondary Diameter | 39mm |
| Secondary Obstruction (by diameter) | 31% |
| Secondary Obstruction by Area | 9% |
| Observational Info | |
| Dawes Limit | 0.91 |
| Rayleigh Limit | 1.1 |
| Limiting Mag. | 13 |
| Minimum Magnification | 18 |
| Maximum Magnification | 250 |
| Light Gathering (compared to next size down) | 55% |
| General Info | |
| Focuser | Primary Mirror |
| OTA Length (Retract/Ext.) | 15" |
| OTA Outer Diameter | 5.75" |
| OTA Weight (with accessories) | 9.7 |
| Accessories | |
| Included Finder | 6x30 Finder |
| Included Diagonal | 2" Star Diagonal |
| Mounting Accessories | V-Rail |
| Included Eyepieces | 28 LET |
| Magnification w/ Included Eyepieces | 55x |
| Included Case | No |
| Corrector | No |