i was looking up eyepieces to buy and what does these letters mean?
SR4 , SR, S ,H
2007-06-10 10:39:41 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
I think SR means Symmetrical Ramsden (4 would be the focal length) and H is Huygens. Not sure about "S".
Huygens and Ramsden are primitive 2-element designs with very narrow fields of view, and will not work at all well in telescopes shorter than f/15. SR4 eyepieces are abominations included with inexpensive telescopes to enable the manufacturer to offer unreasonably high magnification. There is no known use for them. You will be much happier with Plossls.
2007-06-10 11:41:25 · answer #1 · answered by injanier 7 · 1⤊ 0⤋
As Injanier says, these are all junky old designs, and to be avoided. The best bargains in eyepieces today are the Plössls sold by many companies, and the orthoscopics sold by University Optics. They're good but pretty cheap, and it's just a waste of money buying anything cheaper.
2007-06-10 23:17:08 · answer #2 · answered by GeoffG 7 · 0⤊ 0⤋
You're going to need to provide more contextual information. Where are you seeing these letters and what are they describing?
2007-06-10 18:21:07 · answer #3 · answered by Arkalius 5 · 0⤊ 1⤋