香港天文論壇

Wah!! 寫:跟踪精度並不是齒數上的直接比較吧?????

Given the same gear cutting precision, tracking accuracy (or less PE value) depends on the diameter of gear.

My $0.02

LT

五天之前曾經拍過，不過水準差強人意，昨晚再接再厲，對焦同埋對極軸做得比上次好，兩分鐘,300mm 不拉線，但係，風勢都幾大，支photoguider 算係咁，相片只有輕微顫動。 :) canon 400D (mod.) , 300mm F4.OL , ISO 800 , 15x120sec. , P2 filter , dark frame , stacked by DSS . Good try. If you become more familiar with polar aligning your GP2 photo guider and achieve to the claimed a...

Hi Angus, In spite of the not so favorable sky conditions as mentioned by you, this image is still very beautiful, and hope one day I can achieve one M31 image of the same quality as yours. Was this M31 taken with a modded 5D2? If my memory is correct, you should have one modded 5D. Was it sold out?...

Hi, I know there are some folks here preparing for their astronomy trip to Taiwan in the coming holidays. For those using Vixen mounts, please be reminded to calibrate the longitude value of your polarscope. Almost all the places in Taiwan are located at longitude value > 120 degrees. So, please use...

Hi, I was assumed that it was better to use a F7 to F8 apo refractor for deep sky imaging under HK's sky conditions. So, I tried to prove my thought by shooting M27 with a Vixen ED115S and 6" F5 newtonian for comparison. The experiment was not run under the same conditions, and thus the result might...

Nowadays most people may agree that the cheapest choice but reliable enough is QHY5. It is more easier to get the driver/firmware from Dr. Qiu's website to get the guider workable now. Many experience to be shared with from internet around the world now. Also, the price of a 2nd handed netbook is re...

用Borg 60 (325mm) guide Borg 101 (640mm)，個晚見好天"小小"臨急臨忙就set鏡試 SG-4，未較準赤道儀、對pole又"系咁易" [無力感] ...就攪成咁啦 [嘆息] Hi noodle, Theoretically, it is not a hard job for todays autoguiders to guide photographic focal length of just merely 640mm, especially with "Tak" mounts. So, there are some other issues you sh...

Hi Augus,

Please reserve the filter set for me, and check PM also.

LT

Would like to share you with my opinions. 1. Polar alignment is not necessary for goto drives nowadays if visual only or planetary imaging. 2. Can auto-goto any object once 3 star alignment done. The more the star aligned, the better the goto precision performed. 3. Autoguiding is no relationship to...

Thanks for all the kind words from you. Once capturing the flat field, I will rework it again with bias calibrated too.

LT

目前看来，虽然VMC不是Maksutov，但性价比蛮不错的，所以我会首选它。 Intes Micro好象没有出产100mm口径的，所以也就不用看了。 谢谢各位的意见。 Yes, VMC is not the type of Maksutov. At similar aperture, Maksutov does perform better than VMC. But VMC will take less time to cool down and have very least dew issue and be lighter. For low to medium power observ...

Hi, Attached M27 image was taken at the PTC carpark in the evening of September 18th, and please see below for the photographic data. Imaging optical system: Vixen ED115S F7.7 APO refractor @prime focus + LPS + modded EOS 300D @iso800 RAW Photographic focal length: 885mm Equatorial mount: Vixen SXD ...

To all Vixen mount users,

Please be reminded once again, when polar aligning your Vixen equatorial mount of any model in HK, you have to offset the longitude dial to W6, unless the location of the marker has been moved.

LT

Funnoooo, Remind you that the mount base of SXD/SXW is different from that of GP/GPD. That pier is for GP series mount. So, if you want to use your SXD onto it, you need to make one mount base coupler for your SXD. I think the cost is not much if it is made in China. In fact, it is very easy to make...

Attached please find one untouched original image for reference, only Tiff converted from RAW file and cropped in PS, no Level and Curve.

LT