有 1538 筆資料符合您搜尋的條件

David
週日 10 7月, 2011 16:00
版面: 天文攝影 Astrophotography
主題: M20: Trifid Nebula (三裂星雲)
回覆: 29
觀看: 8098

Excellent M20! [Good Job]
David
週六 09 7月, 2011 08:46
版面: 天文攝影 Astrophotography
主題: Omega Centauri (半人馬座Ω星團)
回覆: 21
觀看: 5075

This one is really nice. Thanks for sharing. :D
David
週五 01 7月, 2011 10:24
版面: 天文攝影 Astrophotography
主題: 光害濾鏡能在那裏購買到?
回覆: 5
觀看: 5437

鄧登凳 寫:可找tan14...另一個自稱社長的也自稱是香港代理。
Something must be wrong with this official website?
http://www.sciencecenter.net/hutech/dealers.htm
David
週四 23 6月, 2011 08:16
版面: 天文話題 Everything about Astronomy
主題: 目視超新星SN 2011dh
回覆: 5
觀看: 2994

Re: 目視超新星SN 2011dh

Very nice attempt at visual observation of this supernova.
David
週四 23 6月, 2011 08:14
版面: 天文話題 Everything about Astronomy
主題: 月面欣赏和觀察
回覆: 114
觀看: 69028

我最近的測試,覺得 DBK41 跟 toucam 比,並沒有好很多以價格來說,DBK41 是 toucam 的 10 倍,不過拍出來的作品並沒有好10倍頂多好一點點...表情 I suggest you do more research on this because having used Toucam and DBK cameras, I will never go back to Toucam. You will never expect the performance to improve in scale with the cost for any telescope or acc...
David
週二 21 6月, 2011 21:16
版面: 談天說地 Chatting Square
主題: 向 Carl Sagan 致敬系列 -- 絕對推薦﹗﹗﹗﹗
回覆: 9
觀看: 4308

Excellent links!
David
週一 16 5月, 2011 17:22
版面: 天文物理 Astrophysics
主題: 弦理論的簡介(影片介紹)
回覆: 7
觀看: 8144

Re: 弦理論的簡介(影片介紹)

Brian Greene books are very pro-string theory. The Smolin book provides some arguments against it. So I get a more balanced picture of the situation. They will be very easy to read for you. I have been reading some great books on LHC recently, just in case you are interested: Present At the Creation...
David
週日 15 5月, 2011 21:02
版面: 天文物理 Astrophysics
主題: 弦理論的簡介(影片介紹)
回覆: 7
觀看: 8144

Re: 弦理論的簡介(影片介紹)

I also highly recommend three good popular science books that I had read on the subject: The Elegant Universe, by Brian Greene http://www.amazon.com/Elegant-Universe-Superstrings-Dimensions-Ultimate/dp/0375708111/ref=sr_1_1?ie=UTF8&qid=1305464497&sr=8-1 The Trouble with Physics, by Lee Smolin http:/...
David
週二 10 5月, 2011 22:46
版面: 太陽觀測和攝影 Solar Observation & Photography
主題: 20110510 PST Sun
回覆: 20
觀看: 7869

akltsang 寫:多謝 David 兄的 Photoshop 指導。
You are welcome! :D
David
週五 29 4月, 2011 20:32
版面: 廠製儀器 Factory Equipment
主題: Reflectors vs Air-spaced vs Oil-spaced APOs
回覆: 38
觀看: 12500

It is normal, "price" is always an interesting point to be discussed in relation to "quality", and that's why the term "Price-Performance" comes up so popular. As long as it is not 'overused', it is okay. I have heard some guy commenting on my LS152T solarscope that it is good but very poor price-t...
David
週五 29 4月, 2011 00:33
版面: 廠製儀器 Factory Equipment
主題: Reflectors vs Air-spaced vs Oil-spaced APOs
回覆: 38
觀看: 12500

Subaru 寫:The person will need different telescopes in his warehouse, and use the one that suit the best base on the specific needs and situation.
Agree, otherwise the person will need to restrict what area of astronomy is his/her focus.
David
週四 28 4月, 2011 15:15
版面: 廠製儀器 Factory Equipment
主題: Reflectors vs Air-spaced vs Oil-spaced APOs
回覆: 38
觀看: 12500

Their test also seems to have implied that an oil-spaced Apo can't be superior over an air-spaced Apo. I myself won't go so far to claim this by just this little test. We share the result here just because the discussion reminded me of a related experience, and I share what I saw. I always believe ...
David
週三 27 4月, 2011 11:45
版面: 廠製儀器 Factory Equipment
主題: Reflectors vs Air-spaced vs Oil-spaced APOs
回覆: 38
觀看: 12500

http://www.astrocafe.hk/viewtopic.php?p=8612#p8612 If Yuri thinks 36m is long enough, and said that what we saw was not surprising to him, then I am not going to argue. I admit there was noticeable improvement by going from 24m to 36m. The 62m test (not observed by me) was done to see whether the 36...
David
週二 26 4月, 2011 16:35
版面: 廠製儀器 Factory Equipment
主題: Reflectors vs Air-spaced vs Oil-spaced APOs
回覆: 38
觀看: 12500

Is 24 meters far enough for 160mm aperture telescope to test its quality? :roll: :roll: That's why it was tested again at longer distance 36m. There was improvement but still not matching some of the top scopes that was tested. Overall, the diffraction rings were brighter than what I expect from a ...
David
週二 26 4月, 2011 16:25
版面: 廠製儀器 Factory Equipment
主題: Reflectors vs Air-spaced vs Oil-spaced APOs
回覆: 38
觀看: 12500

Early this year, I had been able to see the performance of different scopes using artificial star. Some refractors that we looked at included: Tak FC50 APO Tak FC60 APO Tak FC76 APO Sky Watcher Equinox 80ED William Optics Megrez 72mm f/6 APO Sky Watcher 70/500 Archromat Lunt LS60T/CaK Archromat APM ...

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