www.astrocafe.hk

Hi all,

Photo for sharing, details :

Date 13 Aug 2010.
Vixen R200SS , Televue Paracorr V 4 filter , ST2000XM - L 180s X 21 , RGB 180s X2 2X2 binning. Taken at Yuen Long.
Guiding , Vixen 80s (400mm) + 2X barlow . DSI II + PHP
Seeing was bad at the final stage of imaging as the object was low at southwest horizon .

Ben

Not bad! Hope to see more...

Ben 開始喜歡拍些冷門東西了

有兩點疑問，

- 這麼低仰角的東西，拍的焦距又不短，若僅拍RGB會否銳一點? 因為L通道中包括了不能拆解的大氣色差。當然代價是曝光時間長了三倍。

- ST2000的晶片不算大，有沒有試過不加彗差鏡的情況如何?

I setup the scope late . When I started capturing the L channel , I found it needs more than 1 hour exposure so at the "final" stage of the capture , the object went to the low southwest horizon.... I will try RGB only next time to see the differences. Besides , It was really difficult to get "colour" image under severe light polluted sky here.
At F4, I don accept the corner star image if no coma corrector is used. I got two different coma corrector , one is not acceptable in CCD photography, in my opinion..... If you want , I can mail u the test shot.

my guess,

- may be you can use LPS-PS filter together with RGB filters to take color channels? Of course don't bin it, use highest resolution at 1x1.

- I have a Sky Watcher coma corrector, I can loan you for a trial, though not sure if you have M48 extension tube for that to match the required back focus. This coma corrector is different from others like Televue and Baader, it use M48 camera adaptor from Sky Watcher, which is much bigger than T-2 "key hole" which is usually 39mm or smaller, hence improving vignetting significantly on 35mm full frame camera - thought not a big deal for your chip.

社長 寫:my guess,

- may be you can use LPS-PS filter together with RGB filters to take color channels? Of course don't bin it, use highest resolution at 1x1.

- I have a Sky Watcher coma corrector, I can loan you for a trial, though not sure if you have M48 extension tube for that to match the required back focus. This coma corrector is different from others like Televue and Baader, it use M48 camera adaptor from Sky Watcher, which is much bigger than T-2 "key hole" which is usually 39mm or smaller, hence improving vignetting significantly on 35mm full frame camera - thought not a big deal for your chip.

Thanks for your offer, but I have no rings/ adaptors ......

你的ST2000有沒有Nikon鏡頭的接環的? 若有便可以直接用。