What kinds of structures do the eyepiece have?
Generally used are: Huygens eyepiece (h) Seans Eyepiece (SR) Kenier Eyepiece (k) Prosle Eyepiece (PL)
The commonly used Huygens eyepiece has H20 H12.5mm
Commonly used Seans Sr4mm.
Commonly used Kenier Eyepiece has K25 K10
The commonly used Prosle eyepiece is Pl25 Pl12 5 Pl10.5 Pl4
The letter represents the type of eyepiece, the number represents the focal length of the eyepiece, and the focal length is inversely proportional to the magnification when the lens focal length is unchanged.
Magnification of a telescope = focal length of the lens/eyepiece
1, Huygens Eyepiece (h)
Dutch scientist Huygens in 1703 design, there are two flat convex lens composition, Front for the field mirror, behind the eyepiece, their convex lens towards one end, the field mirror focal length is generally eyepiece 2-3 times, lens spacing is their focal length of the sum of half. The Huygens eyepiece field is about 25-40 degrees. In the past, Huygens eyepiece is the first choice of small refractive mirror, but with the increase of the telescope's light force, its field of view is small, the contrast is low, the color difference, the ball Difference field song obvious shortcoming gradually exposes, so at present this kind of structure generally is the microscope eyepiece to adopt.
2, Kellner eyepiece (K, RK)
was developed on the basis of Seans's eyepiece, appeared in 1849, the main improvement is to change the eyepiece of single chip to double gluing achromatic lens, greatly improved the color difference and edge image quality improvement, the field of view to reach 40-50 degrees, low-power with a comfortable out of the pupil distance, so currently in a number of medium and low magnification telescope widely used, but at high magnification performance. In addition, the field mirror of the Kellner eyepiece is close to the focal plane, so the dust on the field mirror is easy to be imaged, affecting observation, so pay special attention to cleanliness. A company in the United States on the basis of Kellner eyepiece further improved, developed the Rke eyepiece, its edge image quality better than the classic structure.
3, the Cape Russell Eyepiece (PL)
Also known as the symmetrical eyepiece. From the identical two sets of double gluing achromatic lens, its parameter performance and OL eyepiece is equivalent, but has the bigger pupil distance and the field of view, the cost is lower, and applies to all magnification, is currently the most widely used eyepiece, has derived a variety of improved type.