主要是用来确定跟踪无误之用,使用肉眼导星,目标可以导星100mm的镜头。
由于携带上受到限制,所以想知道把8x50 finder改成导星镜,请问是否可行?
我一路来使用60mm口径、420mm焦距的望远镜作导星用途,可以肉眼导星至500mm的镜头或望远镜,而8x50 finder的物镜焦距应该有170mm左右,把之改装后,应该可以导100mm的镜头吧?
请高手给给意见。
[听取意见]把 8x50 finder 改成 guider
- universe24
- 中子星
- 文章: 1930
- 註冊時間: 週五 11 7月, 2003 20:11
- 來自: Malaysia
The idea of modifying a finder scope to a guiding scope with a barlow has been discussed here:
http://www.astrocafe.hk/viewtopic.php?f=9&t=31
Cheap 2X & 3X barlows can be found easily. I have seen before and it works. It is a cheap & light option. The point is that one needs to make sure the focal length of the finder scope falls into the approperate range before doing the modification becasue the custom made adpator to fit the barlow and eyepiece holder would be more expensive than the finder scope.
http://www.astrocafe.hk/viewtopic.php?f=9&t=31
Cheap 2X & 3X barlows can be found easily. I have seen before and it works. It is a cheap & light option. The point is that one needs to make sure the focal length of the finder scope falls into the approperate range before doing the modification becasue the custom made adpator to fit the barlow and eyepiece holder would be more expensive than the finder scope.
It's Vixen GA-4. It's optical.willis 寫:Oh! Overlooked! The GA-4 has 3X function. Is it optical or digital?
http://www.vixenoptics.com/PDF/illumina ... uider.html
Is it 24.5mm or 31.7mm?
So no extra barlow needed. However I guess the costs of the custom made adaptor to couple the finder scope & GA-4 may be cheaper, but not significant.roh 寫:It's Vixen GA-4. It's optical.willis 寫:Oh! Overlooked! The GA-4 has 3X function. Is it optical or digital?
http://www.vixenoptics.com/PDF/illumina ... uider.html
Is it 24.5mm or 31.7mm?
Re: [听取意见]把 8x50 finder 改成 guider
我既不是高手, 也沒有這方面的經驗, 只是多口說兩句。universe24 寫:主要是用来确定跟踪无误之用,使用肉眼导星,目标可以导星100mm的镜头。
由于携带上受到限制,所以想知道把8x50 finder改成导星镜,请问是否可行?
我一路来使用60mm口径、420mm焦距的望远镜作导星用途,可以肉眼导星至500mm的镜头或望远镜,而8x50 finder的物镜焦距应该有170mm左右,把之改装后,应该可以导100mm的镜头吧?
请高手给给意见。
100mm鏡頭, 用於350D, 水平的視場(fov)寛度是12° 40‘ 8", CMOS水平有3456點, 即每點是13.2角秒。
50mm口徑的尋星鏡, 最高可能的分辨率(Dawes' limit)是 116/50 = 2.32角秒, 那即使尋星鏡的光學系統只達最高額的20%, 那仍可以察覺2.32 x 5 = 11.6角秒的差別/移動, 應足夠作為100mm鏡頭目視導星之用了。
另人眼(20/20視力)的分辨能力為1角分, 那8X鏡下, 分辨能力為 60"/8 = 7.5", 即8X 己足夠目眼導100mm鏡頭之用。
尋星鏡本身有十字線, 有些更有小紅燈, 不用改裝了。
- universe24
- 中子星
- 文章: 1930
- 註冊時間: 週五 11 7月, 2003 20:11
- 來自: Malaysia
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