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引用 | 編輯
aa
2012-04-02 19:12 |
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x0
天氣不好，加上太忙 所以一直沒有空試 昨天抽空試裝看看 不過不知道這個是要接在調焦座前 還是調焦座後呢? 後來在國外的論壇找到一篇討論 要放在前面才不會有暗角 http://www.cloudynights.com/ubbarchive/showflat.php/Cat/0/Number/1975883/page/14/view/collapsed/sb/5/o/all/fpart/1 沒想到國外那個同好用跟我一樣用 JMI 的調焦座 圖 1.  圖 2.  圖 3.  圖 4.  最後試裝在後面，不過我沒有轉接環可以接相機  x1
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引用 | 編輯
aa
2012-04-05 15:48 |
2樓
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下面是引用 一番榨 於 2012-04-05 15:17 發表的 : 那個電動調焦座在對焦時很方便 你可以參考那一篇 http://bbs.mychat.to/reads.php?tid=930711&keyword=jmi 主要是因為 C8 的主鏡調焦，是移動主鏡片 而因為只有一個拉動點，所以調焦時，主鏡不會很平的移動 這樣會造成對好的目標會跑出目視範圍，這樣要再重對目標，就麻煩了 加了那個電動調焦座，只要主鏡調焦到一個範圍，把目前對到 然後就可以用那個來微調焦聚，這樣目標不會跑來跑去 而那個減焦鏡用途，主要是因為 C8 的焦聚太長 (2000mm) 以口徑去算是 F/10 ，這樣在拍深空天體時，會很暗 需要曝光更久才可以拍目標拍下來，而要曝越久，又會有另一個問題 就是追踨不準就拖線了 加上減焦鏡後，可以變成 F/6.3 這樣就亮很多了，不過焦長也縮小為 1260mm 這樣目標拍出來會比較小，不過不用曝太久就可以拍目標拍出來  x1
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引用 | 編輯
一番榨
2012-04-05 16:13 |
3樓
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daniel chang拍月亮是不是要用這個?
他的鏡頭焦距 2147483647/9221933mm 而C8 的焦聚2000mm 是一樣的算法嗎 x0
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引用 | 編輯
aa
2012-04-05 17:02 |
4樓
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下面是引用 一番榨 於 2012-04-05 16:13 發表的 : 他是用 C9.25 拍的 那個比我的 C8 大 不過焦長沒有大很多 其當初的設計好像是為了拍深空天體 所以弄了一個蠻奇怪的尺寸 因為他的鏡筒比 C8 長很多 不過焦長並沒有增加多少 x0
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引用 | 編輯
aa
2012-04-09 18:48 |
6樓
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下面是引用 yccycc 於 2012-04-09 10:48 發表的 : 我不是很確定也，你可以看一下 opt 上的規格 http://www.optcorp.com/product.aspx?pid=410&tb=2&kw=F/6.3&st=2 meade 有他自己的減焦鏡啊 http://www.optcorp.com/product.aspx?pid=778&kw=F/6.3&st=2 x0
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引用 | 編輯
yccycc
2012-04-09 22:34 |
7樓
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下面是引用 aa 於 2012-04-09 18:48 發表的 : 謝謝您.. 看資料好像是 Antares 的減焦鏡比 Meade 好用.. http://www.optcorp.com/product.aspx?pid=8580&tb=8 Antares vs Meade comparison I recently had the opportunity to compare the Antares f/6.3 SCT Reducer/Corrector with the Meade f/6.3 Series 4000 Focal Reducer/Field Flattener. The Antares focal reducer comes in a small box. Unlike the Meade f/6.3 Series 4000 Focal Reducer/Field Flattener, the Antares has only one cover, which surprised me. You attach the focal reducer to the rear port on a SCT and can keep it covered. But when not in the box or on the telescope, there is no cover for the other end. I wish there was. With a 2000mm focal length f/10 telescope like a 8 SC or 8 ACF, both the Antares reducer and the Meade reducer should yield a 1260mm focal length f/6.3 telescope. This makes the telescope a faster system with a wider field-of-view and brighter objects, requiring shorter exposure times when doing astrophotography. Unlike a problem I had with the Meade focal reducer, I had no problems focusing eyepieces or my Nikon D70 DSLR camera on either an 8 LX90-ACF or an 8 LX200-ACF with the Antares focal reducer. I did notice an image size difference between the Meade and Antares focal reducers when using the same setup. When I attached an Off-Axis Guider, the guide eyepiece field-of-view was not restricted, unlike what occurred with the Meade reducer. For visual work, the Antares reducer worked fine with all the eyepieces (both 1.25 and 2 I tested on both the LX90 and LX200. The expanded field-of-view and the increased brightness of objects really added some enjoyment to the viewing. Depending on the telescope/eyepiece combination, there was no distortion or minimal distortion at the edge of the field-of-view. When distortion was visible, it was not distracting. I was very pleased in the images I was able to capture with my DSLR when using the Antares reducer. The increased speed of the system made a considerable difference in what could be photographed in the 3-5 minutes that the exposures could be made when mounted in Altitude/Azimuth, without experiencing field rotation. One thing to keep in mind when using a focal reducer with an Alt/Az fork-mounted telescope is the eyepiece/camera clearance from the base. I found that the maximum elevation on the LX90 and LX200 can vary from 90 degrees to less than 65 degrees, depending on the accessories used. Based on my photographic and visual tests, I prefer the Antares focal reducer over the Meade focal reducer. The Antares focused in all my test scenarios whereas the Meade reducer had problems reaching a focus with most of my accessories. The physical and optical quality seemed to be essentially identical for both but the Antares model is somewhat less costly. x0
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引用 | 編輯
aa
2012-04-10 09:09 |
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下面是引用 yccycc 於 2012-04-09 22:34 發表的 : 對啊 你可以看一下下面這篇分享文 http://www.weasner.com/lx90/accessory_reviews/focal_reducers.html 最後有提到用 1.25" 目鏡 Meade 會有周邊變形，Antares 不會 用 2" 目鏡時 Antares 會有一些周邊變形，而 Meade 是不能合焦  x0
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