The TMB Planetary eyepiece design was developed by optical designer Thomas M. Back (TMB) with the goal of achieving refractor-like sharpness and contrast in a compact, affordable package. It’s based on a modified orthoscopic/Plössl principle, optimized to reduce common issues such as internal reflections, ghosting, and lateral color while maintaining excellent edge sharpness across a relatively wide 58° apparent field.
Each eyepiece uses high-quality glass elements with advanced multi-coatings to maximize light transmission and suppress scatter, resulting in crisp planetary and lunar details. The design also emphasizes long eye relief and comfortable viewing, even at short focal lengths—something many traditional high-power eyepieces lack.
Technical Specifications
| Specification | Description |
|---|---|
| Apparent Field of View | 58° (wide field) |
| Barrel Size | 1.25″ standard format |
| Eye Relief | 16 mm (long eye relief for comfort) |
| Optical Coatings | Fully multi-coated with anti-reflective green film |
| Available Focal Lengths | 3.2 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm |
In the Box
1.25'' eyepiece at selected focal length :