The SVBONY 4mm 58° Planetary Eyepiece (W2488A) is a fixed focal length, 1.25″ eyepiece for high magnification views of the Moon, planets and suitable compact targets. Its 58° apparent field of view and 15mm eye relief offer a practical combination of viewing space and eye clearance.
High magnification for lunar and planetary observing
A 4mm eyepiece gives high magnification without adding a Barlow lens. Use it to examine lunar features, planetary detail or close double stars when your telescope and atmospheric conditions support the resulting power. Start with a longer focal length eyepiece to locate and centre the target, then change to the 4mm for a closer view.
Magnification is calculated by dividing your telescope’s focal length by 4mm. For example, a 600mm telescope gives 150×, while a 1,000mm telescope gives 250×. These are calculated examples, not guaranteed useful magnifications: aperture, optical alignment, cooling and atmospheric steadiness all affect the view.
Comfortable viewing and contrast-focused construction
- 58° apparent field: provides viewing space around the target at high power.
- 15mm eye relief: the manufacturer’s specified viewing distance from the eye lens, with a fold-down rubber eyecup for positioning your eye.
- Five-element optical design: with fully multi-coated lenses.
- Blackened lens edges and internal anti-reflection threads: help control stray light.
- Safety undercut: on the barrel, used with a properly tightened eyepiece holder.
- Filter-ready barrel: accepts compatible standard 1.25″ eyepiece filters.
Compatibility and choosing the right power
Fits telescope focusers and diagonals with a standard 1.25″ eyepiece holder. A 2″ holder requires a suitable 2″ to 1.25″ adapter. Check that the magnification produced by a 4mm eyepiece is appropriate for your telescope; on long focal length instruments it can be too high for typical seeing. This is a fixed 4mm eyepiece, not a zoom.
Specifications
| Brand / SKU | SVBONY / W2488A |
|---|---|
| Focal length | 4mm, fixed |
| Apparent field of view | 58° |
| Barrel size | 1.25″ |
| Eye relief | 15mm |
| Eye lens diameter | 21mm |
| Optical elements | 5 |
| Coatings | Fully multi-coated |
| Eyecup | Fold-down rubber |
| Filter fitting | Standard 1.25″ eyepiece filter thread |
| Net weight | 160g |
What’s included
- SVBONY W2488A 4mm 58° planetary eyepiece
- Lens caps for both ends
Explore other focal lengths
Browse our SVBONY telescope eyepieces to choose lower powers for finding targets and observing wider fields.