天文攝影雜談

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universe24
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文章 universe24 » 週五 19 11月, 2010 16:34

湿气可以通过机身溜进去的...除非此机的设计原本就有一个chamber盖着CCD。

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Subaru
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文章 Subaru » 週五 19 11月, 2010 21:42

Wah!! 寫:意思是否再在原本的玻璃前面不遠處再加一塊濾鏡, 兩片玻璃之間的空間為干燥密封?
對.

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Subaru
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文章 Subaru » 週三 09 2月, 2011 23:08

解決QHY8 CCD的焦平問題:

QHY8的CCD, 好像只係除便連個鋁架安裝在機身上, 不知道出廠的時候有沒有make sure CCD是跟光軸orthogonal!

以現在CCD的解像力, 塊CCD只要有些少唔平, 就會影響影像質素. 於是買把深度呎, 度一度塊CCD的tilt, 不出所料, 都有幾大誤差.

把心一橫, 拆開個QHY8, 把適當厚度的錫紙墊在鋁架所在三粒螺絲的位置, 來把粒CCD盡量平衡安放, 把外殼裝回, 再利用深度呎量度, 利用機背的四粒螺絲微調, 經過多番調校及嘗試, 現在所出的星像終於改善了.
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Subaru
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文章 Subaru » 週五 18 2月, 2011 18:08

窮人QSI WSG:

拍長焦深空, 心裡總是想用off axis guiding, 去盡量減少flexure問題, 但QSI583WSG的價錢居高林下, 而且自己還是對Sony CCD(可惜APS-C的只有bayer matrix版)的表現較有信心, 在有限的資金之下, 只有運用手上的器材去做.

好在得到一位高手的幫忙, 整咗組adapter, 把QHY5及TS OAG 9裝在QHY8上.

現在終於有一套全國產的'dual chips' CCD可以測試長焦攝影了.
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anyone
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文章 anyone » 週五 18 2月, 2011 22:43

Subaru 師兄,期待你用呢套組合,攝製多些精彩的深空天體! [Good Job]

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昇仔
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文章 昇仔 » 週三 18 5月, 2011 22:10

Subaru 寫:解決QHY8 CCD的焦平問題:

QHY8的CCD, 好像只係除便連個鋁架安裝在機身上, 不知道出廠的時候有沒有make sure CCD是跟光軸orthogonal!

以現在CCD的解像力, 塊CCD只要有些少唔平, 就會影響影像質素. 於是買把深度呎, 度一度塊CCD的tilt, 不出所料, 都有幾大誤差.

把心一橫, 拆開個QHY8, 把適當厚度的錫紙墊在鋁架所在三粒螺絲的位置, 來把粒CCD盡量平衡安放, 把外殼裝回, 再利用深度呎量度, 利用機背的四粒螺絲微調, 經過多番調校及嘗試, 現在所出的星像終於改善了.
不過這不是人人都可以自己做到呢,如果花成萬元買個 CCD 光軸有問題,又有 dew 問題,真係覺得好唔抵 :roll: 未知 QHY8 Pro 或以上的 model 對光軸和 dew 的問題是否有改善呢? 不過以我所知,Noodle 兄因為 dew 問題對 QHY8 Pro 大為不滿 :lol: 重話死都唔再用。

基本上 QHY10 個 D CCD size 一樣,只係 pixel 多左,但係 pixel size 又細左,QE 不變,出來個 output 反而重低左,有時唔明點解咁都會買貴左咁多。

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Subaru
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文章 Subaru » 週三 18 5月, 2011 23:16

昇仔 寫:
Subaru 寫:解決QHY8 CCD的焦平問題:

QHY8的CCD, 好像只係除便連個鋁架安裝在機身上, 不知道出廠的時候有沒有make sure CCD是跟光軸orthogonal!

以現在CCD的解像力, 塊CCD只要有些少唔平, 就會影響影像質素. 於是買把深度呎, 度一度塊CCD的tilt, 不出所料, 都有幾大誤差.

把心一橫, 拆開個QHY8, 把適當厚度的錫紙墊在鋁架所在三粒螺絲的位置, 來把粒CCD盡量平衡安放, 把外殼裝回, 再利用深度呎量度, 利用機背的四粒螺絲微調, 經過多番調校及嘗試, 現在所出的星像終於改善了.
不過這不是人人都可以自己做到呢,如果花成萬元買個 CCD 光軸有問題,又有 dew 問題,真係覺得好唔抵 :roll: 未知 QHY8 Pro 或以上的 model 對光軸和 dew 的問題是否有改善呢? 不過以我所知,Noodle 兄因為 dew 問題對 QHY8 Pro 大為不滿 :lol: 重話死都唔再用。

基本上 QHY10 個 D CCD size 一樣,只係 pixel 多左,但係 pixel size 又細左,QE 不變,出來個 output 反而重低左,有時唔明點解咁都會買貴左咁多。
無計, 在下銀兩有限, 其他冷凍相機全部都萬萬聲, 我唯有抱著用一件lab prototype的心態去改善手頭上的器材把它發揮出來.

結霜問題其實有幾個解決方案, 我現在用新的3mm optical window, 再沒有結霜問題了. 用折射鏡的話, 差不多可以不用擔心結霜問題.

其實ST8300原本都有結霜問題, SBIG之後出個heater去解決.

Sensor Othogonality方面, 我相信QHY8Pro/10/12同QHY8都係一樣, 所以QHY出個tilt & centering adjustment ring, 讓用家自己校. 當然, 在下覺得呢樣嘢應該係廠方於出廠時應該調校好的!

可能在下以前都係用自製鏡的關係, 要嘗試解決呢d問題都只當作學習的一種途徑, 不過時間方面的確用多了.

我喜歡天文也是科學的一種, 有很多地方去explore, 是一種樂趣. 可能現代人已經變得越來越consumer driver, 對很多東西也有許多要求. 我反而覺得用一些primitive的設備可以帶來更多樂趣, 當然如果太煩的話就梗係咪攪啦.

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noodle
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文章 noodle » 週四 19 5月, 2011 08:21

其實我都鐘意落手落腳調較器材,但系xxx d CCD要"攪完"硬件、攪軟件。
你上個網頁睇睇download driver你就知"幾正" :twisted:
人地SBIG一個driver 就OK,佢就隻隻唔同。
如果你喜歡挑戰耐力,絕對值得一試。 :wink:
而且呢幾年佢都加左價,相對其他品牌其實一d都唔平。 :wink:

不隻5仔又真系幾抵用
:wink:

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Subaru
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文章 Subaru » 週四 19 5月, 2011 21:18

noodle 寫:而且呢幾年佢都加左價,相對其他品牌其實一d都唔平。 :wink:
呢樣真, 依家個offical價個競爭力真係.....

anguslau
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文章 anguslau » 週四 19 5月, 2011 23:27

Having used a QHY5 for a while, I also swear that I'll never use QHY products again! This is really sad because I honestly think their overall product design is quite good. But the execution and attention to details was extremely poor. I do not understand why they have spent so much effort designing and making a very good product but totally ruin it by not going the last 10%. :cry:

Frankly this also applies to many Chinese products. Only if many of them go a little bit further, they can make a high end product and can compete with the best in the world. But instead, they seem to be satisfied with selling for 50% or 30% of their competitors and earn a poor reputation. IMO, it is not that they do not have the technology or know how. They just do not have the heart. I hope one day (and I am sure this day will come), we'll see the Takahashi of China...

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A/45
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文章 A/45 » 週四 19 5月, 2011 23:30

I had once enquired the price of the QHY12 - it was jaw dropping...

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昇仔
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文章 昇仔 » 週六 21 5月, 2011 00:26

anguslau 寫:Having used a QHY5 for a while, I also swear that I'll never use QHY products again! This is really sad because I honestly think their overall product design is quite good. But the execution and attention to details was extremely poor. I do not understand why they have spent so much effort designing and making a very good product but totally ruin it by not going the last 10%. :cry:

Frankly this also applies to many Chinese products. Only if many of them go a little bit further, they can make a high end product and can compete with the best in the world. But instead, they seem to be satisfied with selling for 50% or 30% of their competitors and earn a poor reputation. IMO, it is not that they do not have the technology or know how. They just do not have the heart. I hope one day (and I am sure this day will come), we'll see the Takahashi of China...
Not only Chinese products, but services as well. A newly opened 5-star hotel in the mainland could be excellent in every aspect, from services to decorations, but you may not want to visit it again two years later; the quality of everything will decay so rapidly that the initial investment is completed ruined. :cry:

The problem in mainland products/services is the QC. Now people are only interested in short-term profits and they don't have the perseverance to excel in QC and establish a brand name in the long run. Takahashi of China will come if the education of the people is improved and they demand products and services of better quality. This will steer the economy towards a healthier development. :D

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Subaru
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文章 Subaru » 週日 22 5月, 2011 22:36

DeepSkyStacker疊相的一般設定:

之前提過會把自己用DeepSkyStacker的常設寫出來, 希望可以跟大家分享及研究研究.

RAW/FITS Digital Development Process Settings:

=> Bayer Matrix Transformation: 通常選Bilinear, 可以的話選AHD, 解像力會高一點.

Stacking Parameters:

=> Light: 如果張數夠多, 用Kappa-Sigma, 可以exclude咗d人造衛星及cosmic ray, 張數唔夠就只有用Average
=> Background Calibration用RGB Channels Background Calibration, 底色方面會易調一點.
=> Dark: 要影多一點dark frame (起碼十到廿張, 我自己就用百張), 用Median Kappa-Sigma疊
=> Flat: 跟Dark一樣, 一樣越多越好.
=> Bias: 跟Dark一樣. 如果唔係用bad pixel map就唔洗用bias, 只做dark frame subtraction.
=> Alignment: Automatic
=> Cosmetic: 不要揀Detect and Clean remaining Hot Pixels及Cold Pixels, 我覺得用了反而重多artifacts.

Save output的時候, 如果唔apply setting, 就只會save個疊完的raw, 一般會很暗. 如果用其他天文軟件去調疊完的FITS, 就可以唔apply. 如果用Photoshop去調, 就建議apply, save做16bit的TIFF.

anguslau
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文章 anguslau » 週日 22 5月, 2011 23:28

昇仔 寫:Takahashi of China will come if the education of the people is improved and they demand products and services of better quality. This will steer the economy towards a healthier development. :D
Totally agree! I might sound a bit pessimistic. But I am infact quite optimistic because I see this as a natural process. Similar to other behaviors of mainland Chinese vs HK Chinese. Many people complain that mainland Chinese are rude, impolite, undisicplined, inconsiderate, ruthelss, greedy, uncivilized etc etc. But many forgot that HK people were exactly like that 20-30 years ago! I do not believe there are much intrinsic differences between people from different countries or locations. As mainland Chinese become more educated, more well off, they'll gradually demand higher quality products and services. The main problem right now is that their society at large do not appreciate (actually most cannot even tell) the differences in quality. Hence there is little chance for them to produce products of the highest quality. It will take time. But I am sure it will come one day! Its really not that difficult!! :D

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bingsze
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文章 bingsze » 週二 24 5月, 2011 17:54

anguslau 寫:
昇仔 寫:Takahashi of China will come if the education of the people is improved and they demand products and services of better quality. This will steer the economy towards a healthier development. :D
Totally agree! I might sound a bit pessimistic. But I am infact quite optimistic because I see this as a natural process. Similar to other behaviors of mainland Chinese vs HK Chinese. Many people complain that mainland Chinese are rude, impolite, undisicplined, inconsiderate, ruthelss, greedy, uncivilized etc etc. But many forgot that HK people were exactly like that 20-30 years ago! I do not believe there are much intrinsic differences between people from different countries or locations. As mainland Chinese become more educated, more well off, they'll gradually demand higher quality products and services. The main problem right now is that their society at large do not appreciate (actually most cannot even tell) the differences in quality. Hence there is little chance for them to produce products of the highest quality. It will take time. But I am sure it will come one day! Its really not that difficult!! :D
very true, both of u. :D

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