Test report on ASI120MC planetary webcam

檢測望遠鏡光學部份,赤道儀機械組件,目鏡配件和拍攝器材 CCD等...
回覆文章
Chanlunlun
夸克星
文章: 3784
註冊時間: 週四 09 10月, 2003 21:06

Test report on ASI120MC planetary webcam

文章 Chanlunlun » 週三 06 2月, 2013 09:45

Dear sky shooters,

Recently I have bought an ASI120MC color webcam from ZWO. I must confess that I was charmed by the ZWO homepage inside which shots from Jupiter, Saturn and lunar surface were made by the same cam showing incredible details. Most importantly this cam comes along with an extremely attractive price tag - at a cost of only a fraction of other expensive webcam it delivers images nearly the same, or sometimes in superior, quality.

Is it too good to be true ? I cannot say because I am still at the bottom part of the learning curve. But I still manage to find some of its advantages and disadvantages. What I like it most is

1. Economic – at the price a fraction of the top notch webcam if the ASI really does what it says, it will be a super performer.

2. It has a relatively large senor area – starting from 320 x 240 you can switch through many resolution up to a maximum area of 1280 x 960. I found it useful to use the maximum area to locate the target and then switch to 640 x 480 to take the shot. That saves a lot of time for targeting.

3. Small pixel size – it has pixel size of 3.7 micron which is nearly half the pixel size of a DBK21AU618 or other brands. It means that for the same image size you can pack more pixels within. One very practical advantage – at f/20 you get an image nearly the same size when using a DBK21 operating at f/35. But you have a speed nearly 4 times faster !!

4. Small in size and lighter in weight – which means that telescope won’t get a serious balancing problem.

5. Fast frame rate – in 640 x 480 it can run as fast as 70 fps. Even at 1280 x 960 it can still run at a speed of nearly 20 fps, depends on how fast your computer is. Not bad at all!

6. Very small “ring” effect on Jupiter – this cam produce no or very little “ring” effect (or onion effect) on shooting Jupiter.

What I don’t like :-

1. Again small pixel size means lower S/N ratio. In comparing our old DMK21 it is obviously noisier, despite the fact that the ASI120MC is newer in design. You need careful, and skillful, post image processing not to run the picture into too grainy style. I am certainly not good at it.

2. Like most high tech astronomical product from China, there is no documentations of any kinds comes along with the camera. You need to download the drivers, capturing software and user manual (if any) from the web.

3. You may download a primitive capturing software from ZWO homepage (comes along with its driver) but you most certainly find it inadequate doing planetary shooting. Fortunately the ASI120MC is compatible with SharpCap ( or FireCap ) which is a freeware from the web, but they may not be the best capturing tool for this particular cam .

4. The contrast and saturation of the camera seems to be a little in the low side. The newest DBK21( 618 chip) seems to capture the same target in a more vivid color and in higher contrast. It may be that I am not using the best capturing software.


Below are two pictures captured by the ASI120MC at the date of 1 Feb 2013 while Jupiter was nearly crossing the meridian. The sky was quite steady by that time.

Picture 1 (1 Feb 2013):-
Transparency = 8/10
Steadiness = 7/10

Telescope – Celestron CPC1100 .
Camera – ZWO ASI120MC
Barlow lens – MIZAR ETL-2
Resolution=640x480
Frame Rate = 60 fps.
Colour Space / Compression=RGB24
Exposure time =0.013597s
Brightness=10
Gamma=86
WhiteBalance=Auto
Gain=58 (maximum 100)

Picture 2 (1 Feb 2013):-

Transparency = 8/10
Steadiness = 7/10

Telescope – Celestron CPC1100 .
Camera – ZWO ASI120MC
Barlow lens – MIZAR ETL-2
Resolution=1280x960
Frame Rate (fps)= 16 fps
Colour Space / Compression=RGB24
Exposure time =0.013597s
Brightness=10
Gamma=86
WhiteBalance=Auto
Gain=58

I am still in the process of learning how to use this cam. There is a lot to be done in order to dig out its full potential.

Best regards
Chan Yuk Lun
5 Feb 2013
附加檔案
Capture 2_1_2013 21_06_57D.jpg
Picture 2. “Wide angle“ shot of Jupiter and Ganymede. This is a crop from a 1280 x 960 picture. The size of the image is unchanged. Although the cam produces a little bit low contrast image of Jupiter the surface feature of Ganymede is well resolved, giv
Capture 2_1_2013 21_06_57D.jpg (19.32 KiB) 已瀏覽 22933 次
Capture 2_1_2013 20_28_35C.jpg
Picture 1. This is a 100% size of 640 x 480, operating at f/20 by a C-11. The size of Jupiter is nearly the twice as big when using a DMK on same f/ratio. The image is a little grainy, looks like an image from film. I don’t know how to reduce the noise.
Capture 2_1_2013 20_28_35C.jpg (21.67 KiB) 已瀏覽 22933 次

頭像
bingsze
夸克星
文章: 3939
註冊時間: 週一 15 1月, 2007 18:13
來自: hong kong

文章 bingsze » 週三 06 2月, 2013 14:35

唔怪得,原來c11! :D

Chanlunlun
夸克星
文章: 3784
註冊時間: 週四 09 10月, 2003 21:06

文章 Chanlunlun » 週三 06 2月, 2013 16:24

bingsze 寫:唔怪得,原來c11! :D
Yes. This is our new toy. It will be installed inside the dome, also fully robotic, to shoot planets every clear nights if possible.

頭像
bingsze
夸克星
文章: 3939
註冊時間: 週一 15 1月, 2007 18:13
來自: hong kong

文章 bingsze » 週三 06 2月, 2013 16:28

Chanlunlun 寫:
bingsze 寫:唔怪得,原來c11! :D
Yes. This is our new toy. It will be installed inside the dome, also fully robotic, to shoot planets every clear nights if possible.
強!

頭像
noodle
夸克星
文章: 2833
註冊時間: 週五 04 7月, 2003 16:34
來自: 地球
聯繫:

文章 noodle » 週三 06 2月, 2013 16:50

影得好好呀 [Good Job]
多手幫你整整.....
1. PI 用左 MultiscaleMedican Transform 抽多少少細節同減noise
2. LocalHistogramEqualization 加加 contrast
3. Curves Transformation 拉拉 saturation
4. PS 整整個邊位尐 "洋蔥圈"
附加檔案
JP_CLL-1.jpg
JP_CLL-1.jpg (48.1 KiB) 已瀏覽 22831 次

頭像
bingsze
夸克星
文章: 3939
註冊時間: 週一 15 1月, 2007 18:13
來自: hong kong

文章 bingsze » 週三 06 2月, 2013 18:07

noodle 寫:影得好好呀 [Good Job]
多手幫你整整.....
1. PI 用左 MultiscaleMedican Transform 抽多少少細節同減noise
2. LocalHistogramEqualization 加加 contrast
3. Curves Transformation 拉拉 saturation
4. PS 整整個邊位尐 "洋蔥圈"
其實佢張相內容豐富,只可惜鏡神不是十項全能(其實在做鏡、做dome和影相已經好勁),如果再影多些和懂處理,應該都十分有看頭! :D

Chanlunlun
夸克星
文章: 3784
註冊時間: 週四 09 10月, 2003 21:06

文章 Chanlunlun » 週三 06 2月, 2013 23:13

noodle 寫:影得好好呀 [Good Job]
多手幫你整整.....
1. PI 用左 MultiscaleMedican Transform 抽多少少細節同減noise
2. LocalHistogramEqualization 加加 contrast
3. Curves Transformation 拉拉 saturation
4. PS 整整個邊位尐 "洋蔥圈"
Mr. Noodle, you are just a master of image processing. The image looks much better now !

Someday I must pay a visit to you and to beg for your teaching.

頭像
universe24
中子星
文章: 1914
註冊時間: 週五 11 7月, 2003 20:11
來自: Malaysia

文章 universe24 » 週四 07 2月, 2013 15:03

May I know why is that gain at 58%?
The onion ring may due by the gamma setting. It is good if the contrast of the image being adjusted in post-processing step rather than during imaging. It all the fault of our eyes.

Chanlunlun
夸克星
文章: 3784
註冊時間: 週四 09 10月, 2003 21:06

文章 Chanlunlun » 週五 08 2月, 2013 00:43

universe24 寫:May I know why is that gain at 58%?
The onion ring may due by the gamma setting. It is good if the contrast of the image being adjusted in post-processing step rather than during imaging. It all the fault of our eyes.
I just guess. If the gain is too high the picture will be too noisy. If the gain is too low we need a long exposure time which is harmful to fine details.

So the middle value is chosen.

頭像
daniel cck
夸克星
文章: 2343
註冊時間: 週二 15 7月, 2003 05:06
來自: HK
聯繫:

文章 daniel cck » 週五 08 2月, 2013 05:33

good job! :D

頭像
Tarepanda
夸克星
文章: 9315
註冊時間: 週一 08 11月, 2004 13:28
來自: 香港

文章 Tarepanda » 週五 08 2月, 2013 15:39

[Good Job] [Good Job]

頭像
Subaru
夸克星
文章: 6638
註冊時間: 週三 02 7月, 2003 19:27

文章 Subaru » 週五 08 2月, 2013 17:52

bingsze 寫:
noodle 寫:影得好好呀 [Good Job]
多手幫你整整.....
1. PI 用左 MultiscaleMedican Transform 抽多少少細節同減noise
2. LocalHistogramEqualization 加加 contrast
3. Curves Transformation 拉拉 saturation
4. PS 整整個邊位尐 "洋蔥圈"
其實佢張相內容豐富,只可惜鏡神不是十項全能(其實在做鏡、做dome和影相已經好勁),如果再影多些和懂處理,應該都十分有看頭! :D
唔係喎, 鏡神處理張Capture 2_1_2013 20_28_35C.jpg出得相當自然, noise方面係相機的characteristic唔係鏡神可以控制的地方.

回覆文章

回到「望遠鏡 廠制儀器 測試報告專欄 Telescope Testing Report Center」

誰在線上

正在瀏覽這個版面的使用者:沒有註冊會員 和 1 位訪客