2009年11月中台灣清境的夜空

PeterPeter · 文章由 **PeterPeter** » 週一 23 11月, 2009 02:49

小弟於2009年11月中去過台灣清境.
估唔到三個晚上只有一晚可以影星,其餘時間不是有雲便是下雨.

universe24 · 文章由 **universe24** » 週一 23 11月, 2009 07:28

拍得好好哦，每张平均不上10分钟，但云气很多。加个平场就会更好了。

anyone · 文章由 **anyone** » 週一 23 11月, 2009 11:41

Dear peterpeter , 每一幅都好靚，個人最喜歡係馬頭星雲。 [想入非非]

我好努力去拍呢個目標，但係點都拍唔到滿意，看來拍攝地點都佔幾大因素。係時候計劃農曆年的觀星之旅了！

PeterPeter · 文章由 **PeterPeter** » 週一 23 11月, 2009 14:24

universe24 寫:拍得好好哦，每张平均不上10分钟，但云气很多。加个平场就会更好了。

300mm 鏡頭加上 Canon 350D 即等效於 480mm.
把它裝上 GP2 photo guider, 3分鐘是否已達極限呢? 我想都是個人的技術問題為主因.
3分鐘的相, 有三份之一的出現拉線, 不能要.
5分鐘的相, 只有三份之一的有機會有用, 真係要看看彩數如何.
10分鐘的相, 我想都唔感想. 我都想可以拍出10分鐘或以上的相, 可是要用 $ 來 upgrade GP2 photo guider 又要增加體力的負擔和交通運輸的問題.

秋冬季上台灣的清境或高山,要帶一堆衣服和GP2 photo guider 及其特別版的厚料鋁腳架和小型mountTGSP2, 使得跟飛機倉的個人行季重量已超標. 若要帶備更大的mount出遊, 真的不感想像!

Flat field, 我會試試的. 請多多指教.

PeterPeter · 文章由 **PeterPeter** » 週一 23 11月, 2009 14:28

anyone 寫:Dear peterpeter , 每一幅都好靚，個人最喜歡係馬頭星雲。 [想入非非]

我好努力去拍呢個目標，但係點都拍唔到滿意，看來拍攝地點都佔幾大因素。係時候計劃農曆年的觀星之旅了！

打算上台灣的高山嗎? 相信在這裡,你一定可以拍得比我好多多倍呢

anyone · 文章由 **anyone** » 週一 23 11月, 2009 14:42

PeterPeter 寫:
anyone 寫:Dear peterpeter , 每一幅都好靚，個人最喜歡係馬頭星雲。 [想入非非]

我好努力去拍呢個目標，但係點都拍唔到滿意，看來拍攝地點都佔幾大因素。係時候計劃農曆年的觀星之旅了！
打算上台灣的高山嗎? 相信在這裡,你一定可以拍得比我好多多倍呢

計劃中，倒數中，儲蓄中， [壓力]

還有八十三日！

universe24 · 文章由 **universe24** » 週一 23 11月, 2009 15:21

没有留意到你是使用GP2 Photo Guider...。
我对上的经验是使用Vixen GP黑色版的赤道仪做盲跟拍摄的，当时使用FS60C，F6.2，有效焦距就已经374mm了，拍摄5分钟基本没有拉线现象，所以我相信GP2 Photo Guider拍摄300mm应该没有问题，不过前提是平衡一定要做好。
10分钟...我想还是做导星比较保险。

LT · 文章由 LT » 週一 23 11月, 2009 16:15

PeterPeter 寫: 300mm 鏡頭加上 Canon 350D 即等效於 480mm.
把它裝上 GP2 photo guider, 3分鐘是否已達極限呢? 我想都是個人的技術問題為主因.
3分鐘的相, 有三份之一的出現拉線, 不能要.
5分鐘的相, 只有三份之一的有機會有用, 真係要看看彩數如何.
10分鐘的相, 我想都唔感想. 我都想可以拍出10分鐘或以上的相, 可是要用 $ 來 upgrade GP2 photo guider 又要增加體力的負擔和交通運輸的問題.

秋冬季上台灣的清境或高山,要帶一堆衣服和GP2 photo guider 及其特別版的厚料鋁腳架和小型mountTGSP2, 使得跟飛機倉的個人行季重量已超標. 若要帶備更大的mount出遊, 真的不感想像!

Flat field, 我會試試的. 請多多指教.

Hi Peter,

Though you only had a night for astronomy, I do think your astronomy trip is and fruitful and successful too. These are very good shots for a beginner. You just step into astrophotography by a couple of years maybe. For me, I have been involving into this hobby for over 20 years, but up to now, I havn't shot any photos of the quality as yours.

For unguiding with GP2PG, your findings are correct. GP2PG use 144-tooth worm gear. So, the period of one cycle of the worm's rotation is 10 minutes. But within the period, the PE value may jump by 7"-8" (nearly about half of its total PE value)in about 2 minutes which seems a characteristic of all Vixen equatorial mounts. So, if using photographic focal length too long , say 200mm or longer, that amount of PE value may cause star images become short trails in E-W direction with neglecting trails in N-S direction due to inaccurate polar alignment. So, for 3 minute unguided exposure, it is normal to get about 1/3 subs suffering from star trail. If you are lucky to start exposure just at the end of this PE jump, it is possible to get about 5 min with 300mm focal length.

For GPD2, the total PE value is less than GP2, and so that is why Universe24 had experience in unguiding 400mm with 5 mins successfully.

So, if doing unguide with GP2 @ photographic focal length = 300mm, you can take it as a rule that

unguiding exposure = 2 min, about 80% or greater of success
unguiding exposure = 3 min, about 66.7% of success
unguiding exposure = 4 to 5 min, about 50% of success
unguiding exposure > 5 min, % of success drops very dramatically to zero.

Hope this evaluation helpful to you and other GP2 users.

LT

PeterPeter · 文章由 **PeterPeter** » 週一 23 11月, 2009 16:36

LT 寫: So, if doing unguide with GP2 @ photographic focal length = 300mm, you can take it as a rule that

unguiding exposure = 2 min, about 80% or greater of success
unguiding exposure = 3 min, about 66.7% of success
unguiding exposure = 4 to 5 min, about 50% of success
unguiding exposure > 5 min, % of success drops very dramatically to zero.

Hope this evaluation helpful to you and other GP2 users.

LT

Thank you for your useful guideline.
Is there any accessories can be equipped onto the GP2 photo guider to enhance the tracking accuracy.

LT · 文章由 LT » 週一 23 11月, 2009 21:37

Hi Peter,

Technically, it is possible. But the controller DD-2 needs to be modified to connect a ST-4 cable to the direction keys and a relay box is also required.

LT

A/45 · 文章由 **A/45** » 週一 23 11月, 2009 22:13

Hi Peter,

Congratulations to your very successful images with the "right gears"!

PeterPeter · 文章由 **PeterPeter** » 週二 24 11月, 2009 22:20

LT 寫:Hi Peter,

Technically, it is possible. But the controller DD-2 needs to be modified to connect a ST-4 cable to the direction keys and a relay box is also required.

LT

What is ST-4 cable and relay box?
Is there any sample photos for our easy reference?
Shall they work with additional DEC body so as to adjust both of RA and DEC direction during long time photographic process?

Thx

PeterPeter · 文章由 **PeterPeter** » 週二 24 11月, 2009 23:08

A/45 寫: "right gears"!

Yes. It is a fast lens. But 300mm f/2.8 is quite heavy.
I just follow you to shoot with the same lens. However, the pictures from the same lens taken by you at 合歡山 in last year is much much better.

Also thank you LT for teaching me don't use camera ball head on GP2 photo guider with the lens so as to minimize vibration.

shan · 文章由 **shan** » 週三 25 11月, 2009 00:10

PeterPeter 寫:
A/45 寫: "right gears"!
Yes. It is a fast lens. But 300mm f/2.8 is quite heavy.
I just follow you to shoot with the same lens. However, the pictures from the same lens taken by you at 合歡山 in last year is much much better.

Also thank you LT for teaching me don't use camera ball head on GP2 photo guider with the lens so as to minimize vibration.

如果唔用ball head, 咁係用左咩黎呢?

PeterPeter · 文章由 **PeterPeter** » 週三 25 11月, 2009 00:35

shan 寫: 如果唔用ball head, 咁係用左咩黎呢?

直接用mount頭上的縲絲收死相機, 就如用mount頭上的縲絲收死ball head一樣. 使用時係好唔方便,調整相機方向時十分唔習慣. 不過天文鏡放係mount上面都係冇ball head用啦.

香港天文論壇