香港天文論壇

Petming, in your 1st step on settinmg the time circle, you forget to offset the time circle : as HK is +114 E, therefore, it is -6 degree(i.e. west side) of central median of +120 E ( which is +8 hour to UT) . so, you need to set the time circle of -6 W , instead of pointing to the zero position. th...

one more:

this is winter triangle taken via Tamron 19-35mm @f/3.5, exposure time is 15min and was taken at around 1:00am :

Hi, I finnaly acquired an Epson 1650 48bit photo scanner with cheap cost ($850 only). attached pls find one of my wide field photo at orion : technical data : canon EOS 66 / 50mm f/1.8 @f/4 and 15min exposure, photo taken at 27Dec at around 2:00am, Vixen polaris mount with celestron CG-4 motor drive...

hmm.. just curious to know : do the field curvature casued by the telescope, or by the ep itself ?

Wah! 寫:咁即係場曲啦?

In my understanding

eq-5 = made from bosma

celestron cg-5 = made from synta

both are Chinese factory

Wah! 寫:EQ-5是國產的??!
我還以為是外國生產的呢!!!

thank you for your comment. I just return from China yestersday and the most valuable prize for me is the starry night and naked eye horse head.

Hi experts, I have calculated the periodic error of my GP-DX mount / ss2k system ( PEC function is off) with the M36 image taken at TKO site on 13 Dec 03. As I don't know if my method is correct or not, would you please comment my assumptions / deriving methods. all comments are welcomed . (remark: ...

some technical info of Vixen Ss100S for your reference :

aperature : 100mm, focal length : 680mm , f/6.8
achromatic doublet , helical focuser, weight = 2kg.