評Lunt LS152T太陽望遠鏡

Equipment (Solar) - 白光、H-Alpha、Cak光譜觀測及攝影器材

評Lunt LS152T太陽望遠鏡

文章

David » 2010-08-14, 13:54

LS152T望遠鏡的口徑為152mm,是Lunt最大口徑的無遮擋H-alpha太陽望遠鏡,只比最大口徑的太陽濾鏡LS160F小一點。

LS152T套裝包括一個黑色鋁箱、抱箍和Lunt 7-21mm變焦目鏡。阻隔濾鏡方面,我選購了較大的B1800。

這鏡的體積明顯比較一般6吋折射鏡細小很多,不需重型赤道儀,因此使用時很方便,一個人便可把鏡裝上。相比口徑相若而且價錢超過HK$100,000的LS160F外置濾鏡,則起碼要接駁體積和重量較大的7吋折射鏡才能使用,相信一定要有固定天文台的富豪或機構才能擁有。

由此可見,價值約HK$60000的LS152T其實是非常便宜的儀器,對一般業餘太陽觀察者,似乎是終極的選擇。


全新單元式設計

Lunt網站稱LS152T為Modular Solar Telescope,而非如其他望遠鏡稱為Dedicated Solar Telescope ,這是因為LS152T不只適合作hydrogen alpha觀察,也能作Calcium-K、白光太陽觀察和一般夜間觀星,相反其他LS60T和LS100T則只能作hydrogen-alpha太陽觀察。

LS152T的鏡身和一支普通152mm口徑、焦距為900mm的折射鏡完全沒有分別 (LS100T的焦距為800mm。),只是在鏡後裝上一個hydrogen-alpha濾鏡單元(Hydrogen-alpha module),這單元包括hydrogen-alpha濾鏡和氣壓調頻系統。

如果想觀察Calcium-K波段,可除去這hydrogen-alpha濾鏡單元,然後裝上一個需另外購買的Calcium-K濾鏡單元 (Calcium-K module) 。如果想作夜間觀星或一般白光太陽觀察,則可除去這些濾鏡單元,裝上合適的調焦系統和適合的白光太陽觀察器材。
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setup.JPG
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H-alpha module.JPG
H-alpha module.JPG (122.84 KiB) 被瀏覽 26588 次
aluminium box.JPG
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最後由 David 於 2010-08-14, 14:09 編輯,總共編輯了 1 次。
APM 80/480, SW 120mm Equinox, C8, Obsession 18"UC with Argo Navis & StellarCat
Lunt LS60T/CaK, LS152T with DSII
DMK31AF03, DMK21AF04, DBK21AF04
Mark V Binoviewer, Ethos (3.7mm, 6mm, 13mm), 19mm Panoptic, 5mm TMB mono
http://www.imsc.edu.hk/pages/astronomy
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Re: 評Lunt LS152T太陽望遠鏡

文章David » 2010-08-14, 13:55

目視效果

當然,一分錢一分貨,理論上內置濾鏡的太陽影像會較外置濾鏡差,LS60T在這方面的問題不明顯,LS100T卻較差,LS152T的表現又如何?

我把LS152T裝上Skywatcher HEQ5Pro赤道儀,需要三個平衡鎚才可達致平衡,目視和拍攝問題不大,但相信使用較大型的赤道儀會較理想。

調頻後便可以開始正式觀察。運用Televue Nagler 12mm觀察(約75x),整個太陽呈現豐富細節,解像力明顯比100mm濾鏡高。

影像反差極佳,比LS100T為優勝,頻寬絕對合符<0.65A的規格,一個從未看過H-alpha影像的人都能輕易看到表面充滿毛絨絨般的細節。

運用LS100T時,當倍數達100x左右,我便開始覺得影像過暗,因而希望升級。我急不及待用Lunt 7-21mm變焦目鏡於LS152T,用7mm端(約130x)觀察一個巨型日珥,發覺影像光度非常充足,絕對能滿足我的要求。我終於能放下心頭大石,相信不需再升級了。

我再作較低倍觀察(75x) ,留意整個太陽表面的反差和光度是否均勻,發現表現理想,遠較LS100T為佳,這也在拍攝中得到引證。
附加檔案
152_100_comp.jpg
比較LS152T和LS100T的解像度和影像均勻度 (左圖為LS100T的影像)
152_100_comp.jpg (534.16 KiB) 被瀏覽 26591 次
最後由 David 於 2010-08-15, 01:46 編輯,總共編輯了 6 次。
APM 80/480, SW 120mm Equinox, C8, Obsession 18"UC with Argo Navis & StellarCat
Lunt LS60T/CaK, LS152T with DSII
DMK31AF03, DMK21AF04, DBK21AF04
Mark V Binoviewer, Ethos (3.7mm, 6mm, 13mm), 19mm Panoptic, 5mm TMB mono
http://www.imsc.edu.hk/pages/astronomy
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Re: 評Lunt LS152T太陽望遠鏡

文章David » 2010-08-14, 13:55

拍攝表現

插入DMK31相機進行低倍拍攝,由電腦螢光幕可見,反差和光度的均勻度明顯比LS100T優勝。大口徑的集光力强,這個焦距為900mm的鏡,如果加入2.5x增焦鏡拍攝日珥,曝光時間仍可少於1/100s (當然,這數字也取決於相機的增益設定。),對應付日間較差的視寧度有不少幫助。如果用LS100T加入2.5x,曝光時間仍要接近1/30s。

LS152T的調焦座為Starlight Instruments的羽毛調焦 (Feather Touch Focuser),容許很準確的對焦,對攝影的幫助明顯。
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20100813.jpg
20100813.jpg (323.09 KiB) 被瀏覽 26591 次
20100813prom2.jpg
20100813prom2.jpg (142.04 KiB) 被瀏覽 26591 次
最後由 David 於 2010-08-14, 14:11 編輯,總共編輯了 4 次。
APM 80/480, SW 120mm Equinox, C8, Obsession 18"UC with Argo Navis & StellarCat
Lunt LS60T/CaK, LS152T with DSII
DMK31AF03, DMK21AF04, DBK21AF04
Mark V Binoviewer, Ethos (3.7mm, 6mm, 13mm), 19mm Panoptic, 5mm TMB mono
http://www.imsc.edu.hk/pages/astronomy
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Re: 評Lunt LS152T太陽望遠鏡

文章David » 2010-08-14, 13:56

總結

雖然LS152T是一個內置濾鏡系統,但光學表現沒有明顯妥協,是一支優秀的大口徑太陽望遠鏡。

優點:

1. 解像度高、反差高。
2. 影像均勻。
3. 體積和重量不太大,使用方便。
4. 遠比口徑相若的LS160F組合經濟。
5. 氣壓調頻方便使用,可作精細微調。

缺點:

如果很少作高倍觀察和拍攝,則可選擇口徑較小的產品,價錢較便宜。
最後由 David 於 2010-08-15, 01:47 編輯,總共編輯了 1 次。
APM 80/480, SW 120mm Equinox, C8, Obsession 18"UC with Argo Navis & StellarCat
Lunt LS60T/CaK, LS152T with DSII
DMK31AF03, DMK21AF04, DBK21AF04
Mark V Binoviewer, Ethos (3.7mm, 6mm, 13mm), 19mm Panoptic, 5mm TMB mono
http://www.imsc.edu.hk/pages/astronomy
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Re: 評Lunt LS152T太陽望遠鏡

文章willis » 2010-08-15, 00:00

The detail & uniformity are stunning! :o I guess u can make lots of world class solar images with this super rocket! Certainly u can go beyond the well known sungazer:
http://www.sungazer.net/index.html
At the same time, I dare not to post any solar images with my little LS35T... :oops:
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Re: 評Lunt LS152T太陽望遠鏡

文章社長 » 2010-08-15, 01:10

Thanks David for this in-depth sharing on LS152T.

- 讓我稍後安排一下和LS160F一起測試吧

- 會否加入Cak Module的測試?

- 這台鏡可以考慮架在經緯儀上作日常目視用

- 上次用LS160F時,發現廣角目鏡如Ethos等有實際作用,因為這個口徑能支撐得起高倍率,而觀測太陽又最好能容下整個日面,那Baader Mark V及兩個Ethos 13用在LS160F上是最好了,你的焦距短些,雙目配兩個Ethos 8應會很好  8-)

- 你手上沒有LS35T,不如用我的去做個對Lunt系統的完整評測?
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配件 - 2 full sets of Supermonocentrics、Baader Mark V Binoviewer、Ethos、Canon 5D Mark II Mod、FLI Proline 16803冷凍相機、Mercedes SUV
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Re: 評Lunt LS152T太陽望遠鏡

文章David » 2010-08-17, 00:28

Here is the English version of the review, also posted in the following links:
http://www.cloudynights.com/ubbthreads/ ... ll/fpart/1

--------------------------------------
LS152 is the largest aperture solar telescope in the market, with an aperture that is only slightly smaller than the largest external filter LS160F. The set arrived in an aluminium case with tube holder and a Lunt 7-21mm zoom eyepiece. I purchased blocking filter B1800 since it is intended for imaging. For visual only, B1200 is good enough according to Lunt website.

The size of this scope is much smaller and lighter than a typical 6 inch refractor and so it does not absolutely demand a very heavy duty mount. For testing, I used Skywatcher HEQ5Pro mount. By comparison, the much more expensive LS160F external filter will at least require a 7 inch refractor. Without a permanent observatory and a lot of money, LS152T is probably my ultimate choice.

Lunt website calls this scope a 'modular solar telescope' rather than a 'dedicated solar telescope' because LS152T is not only suitable for hydrogen alpha observation. With suitable accessories, it can also serve for Calcium-K and white light solar observation, as well as nighttime star-gazing.

The main body of LS152T is no different from a typical refractor. The back side of the scope is fitted with a red component called a hydrogen-alpha module with a 60mm internal filter. It also includes the pressure tuner for adjusting the wavelength.

If one wants to observe in Calcium-K, this module can be replaced by a Calcium-K module which can be purchased separately. If one wants to use the scope for nighttime observation, the module can be removed and replaced by a suitable adaptor. Then one can just add some white light solar observation accessories to view the white light sun.

Theoretically, solar telescopes with internal filter are somewhat compromised in image quality when compared with external filters. The main advantage is their much lower cost. How does LS152T perform?

I first used a Televue Nagler 12mm (about 75x) to view the whole solar disk. The whole sun revealed tremendous amount of details with a resolution that clearly beated 100mm products (LS100T, LS100F) that I had used before. The image was very contrasty in accordance to its bandwidth of <0.65 Angstrom.

When I used LS100T at high magnification (about 100x), I often felt that the image was a bit dim for my taste. With LS152T, using 130x to observe a huge prominence with the Lunt zoom eyepiece, I found that the image was still bright enough for me. My aperture fever has finally been cured.

I went back to lower magnification (75x) to check the uniformity of the image in terms of brightness and contrast. I found that the uniformity was much better than the LS100T that I had used. In fact, as far as I could tell, I didn’t notice any non-uniformity.

Then I tested its performance in photography. Using a DMK camera, the first thing that I noticed was the much better uniformity of the image, confirming my visual impression. The large aperture allowed me to image at very large magnification. With LS152T's focal length of 900mm and using a TV2.5x powermate, I could image a prominence with an exposure time of less than 1/100s (Gain was about 850.) This helped to combat the poor daytime seeing. The focuser of LS152T is the feather touch focuser from Starlight Instruments, allowing very accurate focusing which is important for photography.

Overall, I find that LS152T is an excellent solar telescope with internal filter without obvious compromise in image quality. It is a superb instrument if one is very interested in high magnification observation and photography but with a limited budget.
APM 80/480, SW 120mm Equinox, C8, Obsession 18"UC with Argo Navis & StellarCat
Lunt LS60T/CaK, LS152T with DSII
DMK31AF03, DMK21AF04, DBK21AF04
Mark V Binoviewer, Ethos (3.7mm, 6mm, 13mm), 19mm Panoptic, 5mm TMB mono
http://www.imsc.edu.hk/pages/astronomy
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Re: 評Lunt LS152T太陽望遠鏡

文章社長 » 2010-08-17, 10:14

David, thanks for the great review.
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Re: 評Lunt LS152T太陽望遠鏡

文章xiaoer » 2010-08-17, 15:53

David 寫:Overall, I find that LS152T is an excellent solar telescope with internal filter without obvious compromise in image quality. It is a superb instrument if one is very interested in high magnification observation and photography but with a limited budget.

take limit to infinity.......
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Re: 評Lunt LS152T太陽望遠鏡

文章David » 2010-08-30, 09:41

I set up LS152T with a bigger mount a few days ago - Skywatcher EQ6. The whole set up is very stable. Two counterweights can just balance the scope.

Will try to add a binoviewer next time. :D
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APM 80/480, SW 120mm Equinox, C8, Obsession 18"UC with Argo Navis & StellarCat
Lunt LS60T/CaK, LS152T with DSII
DMK31AF03, DMK21AF04, DBK21AF04
Mark V Binoviewer, Ethos (3.7mm, 6mm, 13mm), 19mm Panoptic, 5mm TMB mono
http://www.imsc.edu.hk/pages/astronomy
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Re: 評Lunt LS152T太陽望遠鏡

文章社長 » 2010-08-30, 10:14

David 寫:I set up LS152T with a bigger mount a few days ago - Skywatcher EQ6. The whole set up is very stable. Two counterweights can just balance the scope.

Will try to add a binoviewer next time. :D


the setup is very sexy / handsome / muscular, and it takes a muscular man like you to move it around, but I see your two counter weights are at the end of the shaft.... :?

with such aperture, you can push up to 100x plus, yet you may want to maintain full disk view on that, what about binoviewing 2 Ethos 13 or shorter? I got such feeling after observing with NPL college's LS160F 8-)

viewtopic.php?f=19&t=316
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配件 - 2 full sets of Supermonocentrics、Baader Mark V Binoviewer、Ethos、Canon 5D Mark II Mod、FLI Proline 16803冷凍相機、Mercedes SUV
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Re: 評Lunt LS152T太陽望遠鏡

文章David » 2011-02-16, 21:38

社長 寫:會否加入Cak Module的測試?


由於恐怕這鏡在藍光紫光波長的修正不佳,所以我沒有打算買這鏡的Cak Module。
viewtopic.php?f=14&t=744

社長 寫:這台鏡可以考慮架在經緯儀上作日常目視用

近數次的觀察都是用這Microtech TG2經緯儀,輕便方便。
viewtopic.php?f=15&t=716

社長 寫:上次用LS160F時,發現廣角目鏡如Ethos等有實際作用,因為這個口徑能支撐得起高倍率,而觀測太陽又最好能容下整個日面,那Baader Mark V及兩個Ethos 13用在LS160F上是最好了,你的焦距短些,雙目配兩個Ethos 8應會很好

我只有一個Ethos 13mm和Ethos 6mm。
APM 80/480, SW 120mm Equinox, C8, Obsession 18"UC with Argo Navis & StellarCat
Lunt LS60T/CaK, LS152T with DSII
DMK31AF03, DMK21AF04, DBK21AF04
Mark V Binoviewer, Ethos (3.7mm, 6mm, 13mm), 19mm Panoptic, 5mm TMB mono
http://www.imsc.edu.hk/pages/astronomy
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Re: 評Lunt LS152T太陽望遠鏡

文章Robin » 2011-06-30, 11:15

请问LS152所说的无遮挡指的是哪个部分没有遮挡?在市面上有什么镜子有这些遮挡,其原因何在?

LS152有必要用到B3400的blocking filter吗?
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Re: 評Lunt LS152T太陽望遠鏡

文章社長 » 2011-06-30, 13:47

Robin 寫:请问LS152所说的无遮挡指的是哪个部分没有遮挡?在市面上有什么镜子有这些遮挡,其原因何在?

LS152有必要用到B3400的blocking filter吗?


大一點的濾鐿,例如以前的LS75F,要在Etalon腔振濾鏡中間加上三片墊片,以保持平行。功能跟Andy Lunt和他父親David Lunt創辦的Coronado那些中央墊片一樣,只是專利關係他們要改為三片。看香港那一組LS160F的墊片,是全球最大的Etalon了:

viewtopic.php?f=19&t=316

若要做到沒有墊片,Etalon的兩片玻璃的平面精度便要由一般的1/50波長上升至1/100波長,而製作平面玻璃的技術要求,可以說跟其面積成正比,所以我的unobstructed LS75F,就是兩組LS75F的價格,但表現當然也有提升。

LS152的焦距是900mm,即太陽成像只有8mm左右,用到B1800已足夠容是兩個太陽面直徑,無必要上B3400了。用B3400不會有壞處,唯一是貴。

香港那一組LS160F,因為是裝在2050mm焦距的APM 228 f9 APO上,所以要用到B3400。注意B3400一定是用2"調焦筒的,而且不設天頂,所以要另找天頂置於後面。
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配件 - 2 full sets of Supermonocentrics、Baader Mark V Binoviewer、Ethos、Canon 5D Mark II Mod、FLI Proline 16803冷凍相機、Mercedes SUV
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Re: 評Lunt LS152T太陽望遠鏡

文章David » 2014-06-12, 10:24

APM 80/480, SW 120mm Equinox, C8, Obsession 18"UC with Argo Navis & StellarCat
Lunt LS60T/CaK, LS152T with DSII
DMK31AF03, DMK21AF04, DBK21AF04
Mark V Binoviewer, Ethos (3.7mm, 6mm, 13mm), 19mm Panoptic, 5mm TMB mono
http://www.imsc.edu.hk/pages/astronomy
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