Quick Overview
- 120 mm apochromatic 3-element refractor
- 840 mm (f/7)
- Fully multi-coated
- Thread-on field flattener
- 3.0" focuser with micro focus
- 2" Diagonal with dielectric coatings
- 9x50 RA erect-image finderscope
- Canon camera adapter
- Tube rings with CGE style dovetail bar
- Aluminum foam lined case
- 43mm image circle
- OTA Weight: 22 lbs.
- OTA Length: 31.5" Extended and 27.4" Retracted
- Back focus: 75mm
Product Details
Designed wtih the discerning astrophotographer in mind, Sky-Watcher USA’s top-of-the-line Esprit refractors deliver the kind of imaging performance one would expect from telescopes costing thousands of dollars more.
With their three-element air spaced objective lens design, false color is completely eliminated, yielding exceptional contrast and sharpness. The included 2-element field corrector guarantees a flat field across the entire imaging plane. The Sky-Watcher exclusive Helinear Track focusing system provides a smooth, rock-solid focuser with zero image shift.
All Sky-Watcher USA Esprit refractors come with a 9 x 50 right angle finderscope, 2-inch Star diagonal, 2-element field flattener, camera adapter, D-style dovetail and padded case. Everything you need to get out under the stars.
Specifications:
- Optical Design: Refractor
- Field Flattener: Included, thread-on
- Aperture (mm): 120 mm (4.72 in)
- Focal Length: 840 mm
- Focal Ratio: 7
- Finder Scope: 9x50, erect-image, right-angle
- Diagonal: 2", dielectric coatings
- Tube Rings: With 3" (CGE Style) dovetail plate
- Highest Useful Magnification: 283 x
- Lowest Useful Magnification: 17 x
- Resolution (Rayleigh): 1.16 arc seconds
- Resolution (Dawes): .97 arc seconds
- Light Gathering Power (Compared to human eye): 294 x
- Optical Coatings: Fully multi-coated
- Fully Illuminated Field: 43 mm (1.69 in)
- Optical Tube Length: 30 in (762 mm)
- Optical Tube Weight: 23 lbs (10 kg)
Product carries full 2 year manufacturer factory limited warranty (within US only).
Manufacturer part number: S11420
Useful Resources
Manufacturer | Sky Watcher |
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General Specs | |
---|---|
Focuser | 3.4" Dual Speed R&P |
OTA Length | 31.5"/27.4" (Retract/Ext.) |
OTA Outer Diameter | 6.875" |
OTA Weight (with accessories) | 22 lb |
Optical Specs | |
---|---|
Mirror Coatings | N/A |
Lens Coatings | Fully Multi-Coated |
Glass Type | BK7 (2)/FPL-53(ED) |
True Aperture (mm) | 119.75 |
Primary Aperture (mm) | 120 |
Primary Edge Thickness | N/A |
F/Ratio | 7 |
Focal Length (mm) | 840 |
Secondary Obstruction (by diameter) | N/A |
Secondary Obstruction by Area | N/A |
Included Accessories | |
---|---|
Included Finder | 8x50 RACI |
Included Diagonal | 2" Dialetric |
Mounting Accessories | Rings/D-Rail |
Included Eyepieces | None |
Magnification w/ Included Eyepieces | N/A |
Included Case | Yes |
Corrector | Yes |
Observational Specs. | |
---|---|
Dawes Limit | 0.97 |
Rayleigh Limit | 1.16 |
Limiting Mag. | 12.9 |
Minimum Magnification | 17 |
Maximum Magnification | 236 |
Light Gathering (compared to next size down) | 44% |