有 1538 筆資料符合您搜尋的條件

David
週二 26 4月, 2011 11:56
版面: 太陽觀測和攝影 Solar Observation & Photography
主題: 20110425 Sun Spots
回覆: 6
觀看: 4037

Wah!! 寫:I know he has sold the old setup already, then he get the current setup from me :mrgreen: :mrgreen:
I see!
David
週二 26 4月, 2011 10:53
版面: 太陽觀測和攝影 Solar Observation & Photography
主題: 20110425 Sun Spots
回覆: 6
觀看: 4037

I recall that you had a large aperture solar set up. I have always been looking forward to see its visual and imaging performance.

http://www.hkastroforum.net/viewtopic.p ... highlight=
David
週二 26 4月, 2011 10:33
版面: 太陽觀測和攝影 Solar Observation & Photography
主題: 20110425 3D PST Sun!
回覆: 6
觀看: 3385

How many pictures are combined to make this mosaic? Your patience is admirable.
David
週二 26 4月, 2011 00:10
版面: 廠製儀器 Factory Equipment
主題: Reflectors vs Air-spaced vs Oil-spaced APOs
回覆: 38
觀看: 12500

if there are two apo scopes in these two different designs (with all same specs.) and both scopes are well made to their highest standard, can we truly or easily distinguish the better between them? I doubt that.... I would think exactly in the same way as you do before I saw the star test. In fact...
David
週一 25 4月, 2011 10:56
版面: 廠製儀器 Factory Equipment
主題: Reflectors vs Air-spaced vs Oil-spaced APOs
回覆: 38
觀看: 12500

willis 寫:a bit disappointed.
Just 'a bit'?

It was really an 'eye-opener' for me. Initially I thought may be it was just this particular scope showing what we saw. But then even the manufacturer agreed what we saw was within their expectation.
David
週一 18 4月, 2011 13:41
版面: 天文話題 Everything about Astronomy
主題: 月面欣赏和觀察
回覆: 114
觀看: 69030

國外參考資料 http://www.imsc.edu.hk/pages/moon/rupesrecta.html This was a very poor pic taken a few years ago by me. The moon is a wonderful target. In the last week or so I took out my 18" for many times, not for saturn because it is almost the same everyday, but for the moon. Last thursday, just me and...
David
週一 18 4月, 2011 13:22
版面: 天文攝影 Astrophotography
主題: 20110413 月面 - 初試 2.5x Powermate
回覆: 14
觀看: 5752

The terminator is beautiful......but the seeing is not doing justice to your hard work in this mosaic.
David
週五 15 4月, 2011 10:49
版面: 自製天文望遠鏡 Amateur Telescope Making
主題: Nice moon poor mirror (20110414)
回覆: 1
觀看: 2912

Nice moon poor mirror (20110414)

Taken with a 6 inch mirror grinded by a student with a focal length of about 1000mm. The low contrast is because the student didn't bother to finish polishing it completely. :(
David
週四 14 4月, 2011 11:23
版面: 太陽觀測和攝影 Solar Observation & Photography
主題: 20110414 PST Sun 漂亮的日珥!
回覆: 16
觀看: 5770

Re: 20110414 PST Sun 漂亮的日珥!

Wah!! 寫:I love summer!~
I love proms!~
David
週一 11 4月, 2011 01:06
版面: 談天說地 Chatting Square
主題: [另類言論]引力產生的原因終於被發現
回覆: 86
觀看: 25636

Well, the different definitions of weight is just a vey minor issue. The more important aspect is to distinguish the concepts of weight and mass. Most school textbooks should be clear enough about that. Apart from mass versus weight, all Hong Kong school textbooks are also clear about the differenc...
David
週日 10 4月, 2011 20:46
版面: 談天說地 Chatting Square
主題: [另類言論]引力產生的原因終於被發現
回覆: 86
觀看: 25636

Do physicists and engineers also disagree about the meaning of Newton's third law? Or may be I just misunderstand what you wrote earlier. The two camps do not disagree on the meaning of the Newton Laws, only on whether the force by gravitation on a body or the reaction force by a scale/floor/hangin...
David
週日 10 4月, 2011 20:14
版面: 談天說地 Chatting Square
主題: [另類言論]引力產生的原因終於被發現
回覆: 86
觀看: 25636

Understood now. Guess confused readers cannot just read school textbook or they will continue to be confused.
David
週日 10 4月, 2011 18:39
版面: 談天說地 Chatting Square
主題: [另類言論]引力產生的原因終於被發現
回覆: 86
觀看: 25636

Please explain the difference(s) between "apparent weight" and "weight"(beyond being apparent). As far as I know, weight is derived from the vertical force exerted by a person or an object on the floor or any device that prevent(or slow) the person/object from falling. The equal but opposite reacti...
David
週日 10 4月, 2011 16:22
版面: 談天說地 Chatting Square
主題: [另類言論]引力產生的原因終於被發現
回覆: 86
觀看: 25636

鄧登凳 寫:升降機開始上升時, 內裡的人重量會增加
I guess you mean the apparent weight increases, not the weight?
David
週五 08 4月, 2011 20:36
版面: 天文攝影 Astrophotography
主題: 奧米迦星團 @ 紅土地 (另一雜牌配答測試)
回覆: 13
觀看: 3973

Wow, the pic is nice when shrunk. Certainly your best work to date! [Good Job]

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