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CHYeung
週五 11 9月, 2009 21:02
版面: 天文話題 Everything about Astronomy
主題: 恐龍級天文器材大集會?
回覆: 31
觀看: 11157

Wah!! 寫:鏡片或望遠鏡都好呀!
應該有唔少前輩有個支6cm藍色或黃色絕版折射鏡, 唔記得牌子係唔係叫 Astro ?
Astro 的折射鏡是白色的,我尚保留有一支七十年代早期的Astro 6cm折射鏡OTA。


YCH
CHYeung
週三 05 8月, 2009 13:40
版面: 廠製儀器 Factory Equipment
主題: 雙筒望遠鏡的放大問題
回覆: 3
觀看: 2422

從圖片所見,可能是 6.5。


楊志雄
CHYeung
週一 13 7月, 2009 11:58
版面: 自製天文望遠鏡 Amateur Telescope Making
主題: 需要帮助:副镜和主反射物镜间的距离是怎么计算的?
回覆: 4
觀看: 3747

计算副镜和主反射物镜间的距离要考慮(1)調焦座高度(2)鏡筒半徑(3)調焦座面至攝影機焦平面的距离

副镜和主反射物镜间的距离 ~= 物镜焦距-調焦座高度-鏡筒半徑-調焦座面至攝影機焦平面的距离
CHYeung
週日 12 7月, 2009 23:37
版面: 天文話題 Everything about Astronomy
主題: 有無人有衍射光柵 (300-600l/mm) ?
回覆: 6
觀看: 2536

Dear Wah,

I have some very low-quality 25,400 l/inch (1,000 l/mm) plastic replica holographic grating. If you think that it is usable, please contact me.


CH Yeung
CHYeung
週六 27 6月, 2009 11:01
版面: 二手交易場 Second Hand Area
主題: 誠徵新手鏡一支,用於觀星,觀日蝕,拍日蝕照片^^
回覆: 13
觀看: 4945

You will need a sturdy tripod and a slow motion head (e.g. Mizar K mount or MaxVision K-2 http://www.hkastroequipment.com/fj03-02.html) to support your scope.

If you want to do long exposure (more than ~1/10 second) photography through the scope, you also need an equatorial mount.
CHYeung
週四 18 6月, 2009 20:52
版面: 廠製儀器 Factory Equipment
主題: Solar Film
回覆: 3
觀看: 2080

The density 3.8 film is only suitable for high magnification imaging. In my experience, the exposure time is about 1/1000 second at f/20, ISO 100 for the density 3.8 film. I used the density 5.0 film for last year's solar eclipse, correct exposure during the partial phase is in the range of 1/250 to...
CHYeung
週六 13 6月, 2009 15:34
版面: 廠製儀器 Factory Equipment
主題: Will Baader Solar filter be oxidized?
回覆: 4
觀看: 2677

The metal film on Baader solar Film is not silver nor aluminium. It don't seems to oxidise over time but it is affected by mould. Two of my very old filters (> 5 years) developed holes caused by moulding.

YCH
CHYeung
週日 24 5月, 2009 11:41
版面: 廠製儀器 Factory Equipment
主題: Maksutov-Cassegrain Vs Schmidt-Cassegrain
回覆: 28
觀看: 15508

Dear Mr. Chan, I agree that the MN cannot match the overall performance of a ED refractor. The MNs do not offer unvignetted field as wide as the Ed refractor because of the limited size of the secondary. However, a carefully made MN or MC with small secondary will match the on-axis performance of a ...
CHYeung
週五 24 4月, 2009 20:51
版面: 二手交易場 Second Hand Area
主題: 團購 8-24mm 目鏡![到貨了]
回覆: 62
觀看: 18296

jj12667 寫:先在此暫停,上邊經銷這次只能給我13個 + 2個[补加],若有需要那就來第2次團購;如何?
我自己的其中一個先給5coffee 你,請放心啊!
這次15個的款我已先付經銷,估計順利的星期一、二就有貨到手了! [樂奔]
我下星期不在香港,可否五月四日回來後才交錢取貨?
CHYeung
週四 23 4月, 2009 11:32
版面: 二手交易場 Second Hand Area
主題: 團購 8-24mm 目鏡![到貨了]
回覆: 62
觀看: 18296

網上價是350rmb不包郵,那邊聽說也是,我的是......嘿嘿!300rmb郵費平分[估計在5-10rmb元內],有興趣直接跟帖吧!

jj12667 x 2
simonii x1
noodle x1
funoooo x1
pkchung x1
小人 x 1
KS x 1
CHYeung x 1
CHYeung
週三 22 4月, 2009 18:09
版面: 二手交易場 Second Hand Area
主題: 團購 8-24mm 目鏡![到貨了]
回覆: 62
觀看: 18296

我都要一個
CHYeung
週日 19 4月, 2009 10:27
版面: 天文觀測入門 Introduction to Astro Observation
主題: 請問那裹有凸镜賣呢?
回覆: 3
觀看: 7657

可到眼鏡舖買“原度未裁”的圓型老花/遠視鏡片或到相機鋪買Close-up 鏡片

老花/遠視鏡片焦距 = 1000 mm/(度數/100)

100 度鏡片,焦距=1000 mm
250 度鏡片,焦距=400 mm

Close-up 鏡片 +1 = 老花/遠視鏡片100度, +2 = 老花/遠視鏡片200度

但單片鏡片會有較大色差
CHYeung
週二 31 3月, 2009 10:36
版面: 自製天文望遠鏡 Amateur Telescope Making
主題: 如何有效消除金屬支架的振動?
回覆: 30
觀看: 12598

Filling with sand is known to work.
CHYeung
週六 28 3月, 2009 17:36
版面: 自製天文儀器 diy Astro Equipment
主題: 我用酒精擦走左塊反射鏡的霉了....
回覆: 10
觀看: 8420

The iso-propanol or ethyl alcohol used for sterlisation (also known as "rubbing alcohol") contains about 70% of alcohol and the other 30% is water. If you let the "alcohol" to dry by itself, it will left "stains". A better way is to remove the excess alcohol after cleaning by absorbing them with lin...
CHYeung
週五 27 3月, 2009 21:58
版面: 天文活動消息 Astro Activity News
主題: 天文儀器分享 - 2009 年 4 月 18 日 (已截止報名)
回覆: 168
觀看: 44917

地方未定,大家如果有興趣,請在以下作意向報名:
bingsze
Steve
Wah!
anyone
joseph
Eddy So
syyuen168
Tarepanda
Subaru
Tinping
Raymond Tse
noodle
Lam Chi Wah
CH Yeung

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