The Long Waited Sun

It has been cloudy, rainy and humid for more than two months in Hong Kong. The winter was exceptionally bad this year. No stargazing and sungazing for more than two months since last Christmas Eve. Although it has been very busy today, I could not stop myself from the long waited sunshine today. I spent less than one lesson to shot the sun. Everything was in a rush!!!
LS35T, EQ3Pro, DMK41, Registax, PS, top 90% quality of 450 frames stacked

Small 60mm China made refractor and reflection

I just finished the China made 60mm refractor (C60) testing, bulk order from a small China factory. As the absolute measurement is not possible, I compared it side by side with another 60mm Takahashi FS60C. The price difference is 9 times, one would expect there would be big difference. So this report roughly tells you what it means by big difference.
At a first glance, the finish of C60 is bad, however the design is good. It has an extension tube and the eyepiece holder is even equipped with compression ring! One just needs to screw the extension tube into the end of the focuser and it works for webcam.

The handcraft is by no mean good! So what about the optics? I used Nagler 2-4mm and 3-6mm zoom in both C60 and FS60C. The big problem of the C60 is that chromatic aberration in any magnification is pronounced, especially when viewing high contrast objects. In fact I tried to use Baader Planetarium 8-24mm zoom to test the low magnification performance of it, the problem persisted. Another bad design of the C60 is that the inner tube of the focuser is very long and the inner diameter is smaller than 60mm. I guess this makes the effective aperture of C60 smaller! Look at the attached photo. On the other hand, the chromatic aberration in FS60C is very small. One can detects it when the magnification is very high, say larger then 355/2.5=142X. Of course this is a rough figure. The result may vary from different viewing conditions. My subjective opinion about the maximum acceptable magnification of both scope are:
C60: 220/2=110X
FS60C: 355/3x2.5=296X
Beyond the above magnifications, the contrast would be too low.
I used to use 5-point scale to rank telescope. If I keep on use this scale, I must give the C60 negative score! However I found that I was spoiled by those ED/APOs! I have several refractors. Some are achromatic and some are EDs or so-called APOs. After I got the ED/APOs, all my achromatic refractors are sitting in the store room and gather no more photons. I do most of the visual observations and imaging with ED/APO refractors. I never seriously look back the achromatic refractors again. Until this test, my instant feeling was that I bought garbage! Then I dug out my Meade ETX70. Although the finish is good compared with C60, the chromatic aberration is very bad. I do remember I was once satisfied with these achromatic refractors. Now I say they are garbage! I was really spoiled by those ED/APOs! In most of the time when I do optical testing of those ED/APOs, I deliberately push the magnification to limit, point to bright and high contrast objects and do rigorous star tests etc. Radically fault picking the scopes. Sometimes the differences can be only be identified by experienced telescope users. In fact if one is not doing a side by side test, I doubt the results are reliable. I asked myself is it the way to promote astronomy. I can say virtually all the telescopes we used nowadays are much better than the one used by Galileo 400 years ago. His achievement in astronomy was tremendous! I reckon that always talk about prestigious telescopes may not be the way to promote astronomy because the price of those prestigious scopes are too high in some sense. We should introduce more good value scopes, for example Sky-watcher Mak 127, Celestron Nexstar 4SE or even binoculars, to the public. These good value scopes once lead me to the world of astronomy. Anyway, in terms of optics, test result is follow (10-point scale):
C60: 4 (Moderate blue and red aberration, but more contrast than ETX70)
Mead ETX70:5 (Severe violet aberration, but sharper than C60)
Takahashi FS60C: 8 (Sharp, high contrast, by all mean winner in this test)

FS60C Vs C60

Look! The large inner diameter of the focuser tube!

C60 Vs ETX70

Testing the limit of FS60C (355/3x2.5=296X)

31-1-2010 Solar Image

Yesterday got a call from the dealer. He said that my LS35T problem is arisen from the objective, not the etalon. The objective got serious astigmatism. Gosh! When I hear this I was scared because my LS35T is a special edition and the objective was made by Carl Zeiss which means there would be no replacement! The current LS35T uses non-Carl Zeiss objective. I am lucky enough that the last LS35T, there are totally 4 Carl Zeiss editions in Asia, is not sold yet! I can have replacement right the way! Hooray! I will take it home this week and fully utilize it as my F.7 class will be finished.
After more than one month of bad weather. Today is a sunny day. I used the dealer’s courtesy LS35T to shot the sun. Although there is no sunspot, I got two big prominences! Since the diameter of the sun is about 110 times than that of the Earth, the biggest prominence is about 3 times the size of the Earth!

LS35T, DMK41, Porta, Registax 90% quality of 300 frames, PS CS4

LS35T Sent for Repair

After watching the dealer’s Ha angular eclipse photos, I smell something fishy about my LS35T. I watched LS60T, LS70F and LS100T before in David’s solar party. As there were many big solar scopes, I didn’t draw much attention to the LS35T. After I bought my LS35T, I found the detail of the sun surface is not shown clearly. Originally I thought that was normal, LS35T cannot be compared with those big scopes. As u can see in my 1st Ha photo which was shoot by my LS35T. It seemed that it was abnormal. So I found David, who is an experience sun-gazer. He confirmed that my LS35T needed to be repaired. So I sent it back to the dealer for repair. The scope needed to be sent back to US. The dealer is so kind that he lent me his own LS35T. During the waiting, I can still do solar observations! Great! When I went to David, he let me tried his prestigious unobstructed LS70F and APM 80/480. Visually the surface detail shown was wow! The photo was taken by this setup. The photo was not particular good because of my bad skill!

16-1-2010, APM 80/480, LS70F Unobstructed Version, DMK 41

1st Solar Ha Image

This is my 1st Solar Ha Image I took on 12th Jan 2010. This was certainly a bad image. Although it showed a sunspot, even a white light filter can do it. I have used several times my LS35T for visual observation. I knew it shows less detail compared with LS60T, LS75F or LS100T, but I didn’t know it is abnormal or not. Today I confirmed my LS75T is abnormal after I consulted my friend who is experienced in solar observation. Good grief! I need to send it back to the dealer. Hope to get it fixed quickly!

LS35T, HEQ5Pro, DMK41, Registax 5

High Resolution Lunar Mosaic

I did a quick imaging work in Christmas Eve because I needed to rush home for dinner. The seeing was 5/10 and the transparency was 4/10. Originally I want to shoot both Jupiter and moon. However I didn’t make it for the Jupiter. I used the Equinox 120ED and the 5X Powermate for the Jupiter imaging. The effective focal length was 4500mm. It was just too difficult for me to get the image on the DBK21 CCD. I tried for an hour and finally I gave up and switched fast to the moon. It was a good exercise for me to shoot the moon in high magnification. I used the Equinox 120ED and 2.5X Powermate. The effective focal length was 2250mm. It was longer than the focal length of C8. In order to save my work, I intentionally used more margins. I don’t want to ruin the whole image by miss a small parts of the moon. The final mosaic is a composition of 22 photos. I found it was difficult to make the sharpness uniform in all 22 photos. The underlining key is the selection of alignment points, not the number of alignment points and the wavelet. After process the image for more than 15 hours, I gave up! This is the result.

Click here for full size images:

http://wphoto.myvnc.com/24-12-2009_original.jpg

http://wphoto.myvnc.com/24-12-2009_original_bg_rotate.jpg

Moon age 7.9, Equinox 120ED, EQ3Pro, DMK41, Registax 5, PS CS4

Filled background and rotation applied

My Dark Age

Despite the recent cloudy weather in Hong Kong, the weather seems going to be good in the Christmas holiday. I wish clear skies are waiting for me! However, I was totally down today! I went to the Lion Rock Mountain today with the Hiking Club members. Apart from the foggy weather, it was cold and dry. It was good for hiking! However it was my fate too! When we walked for an hour, I needed to check the map to make sure that we were in the right trail. As I needed to find the map from my backpack, I asked one of my students to hold my camera for me. While I was reading the map, he suddenly dropped my camera! Good grief! My D80 and 18-200mm VR were gone! I guessed the D80 would be totally lost! I am not sure about the 18-200mm VR. It needs optical alignment for sure. Anyway, I need to bring them to Nikon and see if they can be recovered. They are now in Intensive Critical Unit, ICU! I told my student that this accident can be fixed by money. I will pay for my beloved camera and lens. But some accidents in physics lab would not be fixed by money, perhaps fatal or irreversible! One must be very careful in handling equipment. Anyway, this is not the end of the story. When we almost finished the hike, I wristed my two ankles 拗柴! It was the first time I hurt both ankles simultaneously! In fact I haven’t seen any people hurt their two angles at the same time! Poor me! I wish I can recover quickly. Otherwise it will ruin my Christmas holiday completely! No stargazing!!!

My two ankles were wristed!

My D80 was seriously damaged! See the gap between the lens and the body. This part is supposed to be very tough! But cracked now!!!

These are the bits and pieces from the inner part of D80 and battery compartment. In fact some parts are missing!