香港天文論壇

THe 102 mm f/7 has a focal length of ~700 mm which is much longer than the 400 mm f/5.6 and this impose a much higher requirement for the equatorial mount.


CH Yeung

Dear Wah!,

Please check PM.


CH Yeung

溫度太低，GP 的軸會轉不動，但 GPD 沒影響。

CHYeung 寫:我都要

UV-pass 2mm x 2
IR-pass x 2
智通濾鏡框 x 6

如有其它 cut-off wavelength 的 IR-pass filter, 我都會考慮要。

楊志雄

Dear Wah,

I confirm my order but with a little change.

UV-pass 27.6 mm diameter 2 mm x 2
IR-pass 27.6 mm diameter, 720nm x 1
IR-pass 27.6 mm diameter, 850nm x 1
智通濾鏡框 x 6

Thank you.

我都要

UV-pass 2mm x 2
IR-pass x 2
智通濾鏡框 x 6

如有其它 cut-off wavelength 的 IR-pass filter, 我都會考慮要。

楊志雄

What focal length are you suing? Is it 300 mm (the logest end of your lens)?

If you are using a 300 mm camera lens, the image is just about 3 mm in diameter and this is it.

noname2002002 寫:希望中國有朝一日都能參加呢一類的前緣研究...

China has a similar setup and had started test runs since September 2006.

<http://english.peopledaily.com.cn/20060 ... 07241.html>

alget 寫:You are welcome!

寶源光學曾經在澳門生產過相機, 想不到還有生產望遠鏡.

是1970至1980年代的產品嗎? 造型相當古典, 看起來很穩重呢.

寶源光學的廠房當年設於北角英皇道（今天是港運城側的香港大學 SPACE 校舍)和鯽魚涌英皇道（今天的 太古坊英皇道的部分?）。當年規範很大，除生產自家品牌，亦代工生產攝影機和雙筒望遠鏡。當年(七十至八十年代初)在鴨寮街很容易買到寶源光學的次品雙筒望遠鏡物鏡。

The objective can be mounted onto a microscope to replace the ordinary objective. You may also use it as an extreme close-up "lenses" but you have to find out the designed "tube length". The tube-length is the distance between the optical center of the optical system and the conjugate focal plane, i...

This reflecting microscope objectives are mainly for the IR range.

In 1761, the British inventor, John Harrison had already produced his 4th marine chronometer (H4) that is accurate to 5 seconds for the journey from England to Jamaica, corresponding to an error of 1.25 minutes in longitude or 1 nautical mile in distance. His fifth marine chronometer (H5) was tested...

Longitude measurements are done by measurement of time of meridian transit of heavenly objects. Time is kept by a "highly accurate" marine chronometer. http://en.wikipedia.org/wiki/Marine_chronometer Latitude is determined by the zenith distance of heavenly objects when they transit the local meridi...

五金舖

售賣火水、石油氣、潤滑油等的石油產品分銷商

好奇問: 我想信佢唔會放棄佢套理論, 同時好難說服佢, 一般人對他的言論恐怕不會有興趣...... 大家為什麼依然願意花時間去回應他呢? :roll: I responded because his theory is a very good example of pseudoscience. By responding to his post and challenging him will demonstrate to those less knowledgeable what is behind a genuine scientific theory. I do not expect ...

你认为小学生能计算出来吗？地球Ｏ点至空气大气层边缘最近距离12869.3882（公里），也就是和恒星的氢氦大气层相交的最近距离。假如对着月亮发射火箭，[ size=18]从地球Ｏ点至12869.3882（公里）就是空气大气层的界点，超出12869.3882（公里），就是氢氦大气层[/size] ，这些小学生都能计算出来？请问金星氢氦大气层你计算是多少公里？知识不要仅限于书本上，书本也是人们在不断地探索中总结出来的，虚心使人进步，骄傲使人落后。尊重别人就是尊重自己。要以理服人。 孫先生, 你的文章中有很多名辭並不是常用的，我和其它同好都不能理解，請你一一詳細定義及解釋，如 空气大气层边缘 氢氦...