A classic four-lens eyepiece with an apparent field of about 50°, sharp and contrasty. It is often the eyepiece supplied with telescopes, and a very good starting point. Its eye relief is about 70% of its focal length, which makes it uncomfortable below 10 mm.
ToolsEyepieces
Related terms
- Eyepiece
The small interchangeable magnifier you look through; it sets the magnification. Its focal length is engraved on it: the shorter it is, the higher the power. The standard barrels are 1.25 inch (31.75 mm) and 2 inch (50.8 mm) wide.
- Wide-angle eyepiece
An eyepiece with an apparent field of 65° to 100° or more, using more lenses. At the same magnification it shows more sky, which helps when finding objects and following a planet with a Dobsonian. It is heavier and bulkier than a Plössl.
- Eye relief
The distance between the eyepiece’s last lens and the spot where your eye must be to see the whole field. Glasses wearers need at least 15 to 20 mm. Short focal length eyepieces of older designs often have very short, uncomfortable eye relief.
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