石澳夜空
鄧登凳, it's tough to do focusing in the small window at night especially I am focusing a tiny star. Using a Bahtinov mask is a bit help but I have to guess the star is focused or not at the end. I may not have the best equipment like others, however, I do enjoy watching stars at night.鄧登凳 寫:It is actually very difficult to use a Bahtinov mask on a 100mm lens.
Focusing with a 300D (no live view) is a nightmare.
If you have tried, you will see that unless you get an extreme fine lined Bahtinov mask, the pattern for lens with focal length less than 135mm is so weak that render the mask useless.
I do not use Bahtinov mask for lenses less than 135mm in focal length even that I have very fine printed mask.
I had a modified 300D as my first camera for astrophotograph. The only way to do it is by trail shot and adjust until you get the smallest star. A painful process indeed.
If you can afford, change to a modified 500D.
I do not use Bahtinov mask for lenses less than 135mm in focal length even that I have very fine printed mask.
I had a modified 300D as my first camera for astrophotograph. The only way to do it is by trail shot and adjust until you get the smallest star. A painful process indeed.
If you can afford, change to a modified 500D.
我的建議:
因所用的100mm焦距也足夠長,可在鏡頭前加一度 十字 線,然後在相機目鏡處加裝一個相機目鏡放大器 (magnifier),倍數越高越好。我用的是2.5倍,Canon原廠。我想國產的應沒大問題。
對星前,要預先cal好放大器的focus,使從放大器能清楚看見對焦片的磨沙表面。
然後找一顆很光的星來對焦。只要對焦星足夠光,可從放大器看得見對焦過程。若對焦接近"準"的位置,會看見亮星帶有清晰的十字繞射條紋。
跟著拍一張,看看拍出來的繞射條紋。若焦點仍差一點點,再輕微調焦及拍照,看看繞射條紋怎樣變化至最好形態。
好像有一點麻煩,但只要熟習後,其實整個過程可短於數分鐘內完成的。
希望對你有一點幫助。
因所用的100mm焦距也足夠長,可在鏡頭前加一度 十字 線,然後在相機目鏡處加裝一個相機目鏡放大器 (magnifier),倍數越高越好。我用的是2.5倍,Canon原廠。我想國產的應沒大問題。
對星前,要預先cal好放大器的focus,使從放大器能清楚看見對焦片的磨沙表面。
然後找一顆很光的星來對焦。只要對焦星足夠光,可從放大器看得見對焦過程。若對焦接近"準"的位置,會看見亮星帶有清晰的十字繞射條紋。
跟著拍一張,看看拍出來的繞射條紋。若焦點仍差一點點,再輕微調焦及拍照,看看繞射條紋怎樣變化至最好形態。
好像有一點麻煩,但只要熟習後,其實整個過程可短於數分鐘內完成的。
希望對你有一點幫助。
LT 寫:我的建議:
因所用的100mm焦距也足夠長,可在鏡頭前加一度 十字 線,然後在相機目鏡處加裝一個相機目鏡放大器 (magnifier),倍數越高越好。我用的是2.5倍,Canon原廠。我想國產的應沒大問題。
對星前,要預先cal好放大器的focus,使從放大器能清楚看見對焦片的磨沙表面。
然後找一顆很光的星來對焦。只要對焦星足夠光,可從放大器看得見對焦過程。若對焦接近"準"的位置,會看見亮星帶有清晰的十字繞射條紋。
跟著拍一張,看看拍出來的繞射條紋。若焦點仍差一點點,再輕微調焦及拍照,看看繞射條紋怎樣變化至最好形態。
好像有一點麻煩,但只要熟習後,其實整個過程可短於數分鐘內完成的。
希望對你有一點幫助。
LT, 多謝指導,我剛試放傻瓜機係觀景窗當放大鏡,效果好似ok, 但要等天氣好實戰一下,多謝 [蔥寶恭喜樣]
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