Product Overview
Ursa Major FMC Flatfield Eyepiece 25mm
An excellent alternative to regular Plossl or Orthoscopic eyepieces.
Ursa Major FMC Flatfield eyepieces have a five to six-element optical design that provides surprisingly high performance, generous eye relief and a wide apparent field of view from 60 to 65 degrees, depending on the focal length.
Their Flatfield design with fully multicoated, edge-blackened optics reduces field curvature and enhances brightness and contrast.
The black-anodised 1.25" nosepiece has a safety taper (for a secure fit in the focuser) and is threaded to accept 1.25" astronomy filters.
Each Ursa Major FMC Flatfield eyepiece is beautifully finished with a tactile grip and a fold-down rubber eye cup for comfortable viewing.
Supplied with a lens cleaning cloth and an eyepiece bag.
Eyepiece Field of View Simulator
Specifications
| Focal Length | Lens Elements/Structure | Apparent Field of View | Eye Relief | Barrel | Coatings | Filter Thread | Field Stop Diameter |
Eye Cup |
| 3.5mm | 6/4 | 60° | 15mm | 1.25" | Fully Multi Coated | M28.5X0.6-3.9 | 3.9mm | Fold Down |
| 5.5mm | 6/4 | 60° | 16mm | 1.25" | Fully Multi Coated | M28.5X0.6-3.9 | 6.4mm | Fold Down |
| 7.5mm | 6/4 | 60° | 16mm | 1.25" | Fully Multi Coated | M28.5X0.6-3.9 | 8.6mm | Fold Down |
| 10.5mm | 5/4 | 60° | 16mm | 1.25" | Fully Multi Coated | M28.5X0.6-3.9 | 11.7mm | Fold Down |
| 15.5mm | 5/3 | 65° | 16mm | 1.25" | Fully Multi Coated | M28.5X0.6-3.9 | 17.4mm | Fold Down |
| 19mm | 5/3 | 65° | 20mm | 1.25" | Fully Multi Coated | M28.5X0.6-3.9 | 20.3mm | Fold Down |
| 25mm | 5/3 | 65° | 23mm | 1.25" | Fully Multi Coated | M28.5X0.6-3.9 | 25.9mm | Fold Down |
