Sky-Watcher SKU: S11220 | Helix SKU: CTS11220
| SKU | S11220 |
| UPC | 050234112208 |
| Optical Info | |
|---|---|
| Optical Design | Newtonian |
| Mirror Coatings | 94% Aluminum |
| Glass Type | Borosilicate |
| True Aperture (mm) | 257 |
| Primary Aperture (mm) | 254 |
| F/Ratio | 4 |
| Focal Length (mm) | 1000 |
| Secondary Diameter | 89mm |
| Secondary Obstruction (by diameter) | 35% |
| Secondary Obstruction by Area | 12% |
| Observational Info | |
| Dawes Limit | 0.46 |
| Rayleigh Limit | 0.55 |
| Limiting Mag. | 14.5 |
| Minimum Magnification | 36 |
| Maximum Magnification | 500 |
| Light Gathering (compared to next size down) | 57% |
| General Info | |
| Focuser | 2" Dual Speed Crayford |
| OTA Length (Retract/Ext.) | 36.5" |
| OTA Outer Diameter | 11.375" |
| OTA Weight (with accessories) | 36.5 |
| Accessories | |
| Included Finder | 9x50 Finder |
| Included Diagonal | No |
| Mounting Accessories | Rings/V-Rail |
| Included Eyepieces | None |
| Included Case | No |
| Corrector | No (optional) |