Thursday, February 23, 2012

DIY Solar Telescopes?

First up is Dave Groski's famous design, check out his website for a decent description:

And that filter pair could be bought from ebay, slightly more expensive than the above website mentioned:

And actually, this possibility also works for CaK for you can get a pretty cheap CaK filter from Omega Optical.  They have some CaK (394 +/- 3nm) filters selling at pretty cheap price!  And just for comparison, Lunt's CaK module is 2.4A while PST is around 2.2A, and the Baader CaK filter is 80A!  Therefore, this filter from Omega Optical actually sits between those professional offerings and it's even better than the one from Baader at least on paper.

Wednesday, February 22, 2012

Motorizing the focuser of my Ranger?

I have been using a NGF-CM for my Ranger for quite a long time.  Like some amateur astronomers suggest, motorized focusing is somehow a must for imaging since whenever you touch the focuser, you will affect the image and so hand free focusing is a good way to get into a better focus.

NGF-CM brings too benefits, one is motorized focusing and the other one is 2" capability.  I really love my Pentax XL 40mm but then it's probably the only reason for me to keep the NGF-CM.

Today, I pulled out my original Ranger focuser and I believe that it might not hard to motorize it, and I might even use the small DC motor which I've used to motorize the 127mm Maksutov!  I just need a longer belt. 

I shall explore that a bit further, it saves some more money by kicking the NGF-CM out of the equation.  Actually, the NGF-CM has a third benefit but it's no longer applicable to me, it's the capability to allow the use of a stronger reducer for taking H-alpha full disc image in one shot.

After measurements:

A 45-50mm belt should work for my Ranger, however, problem is, the helical focuser will move along with the draw-tube, so the motor fixing mechanism has to be movable as well.

A 35-40mm belt should work for my 127mm Maksutov.

Saturday, February 18, 2012

Beating Seeing


Back home seeing Venus hanging in the sky, so I pulled out my 127mm Maksutov to try.  Jupiter was not in a good location, otherwise I should have used it for testing.

First one is taken with a 2x barlows, no filter:-

Second one is taken with a 2x barlows, green filter:-

So a green filter will really help to reduce the effect of bad seeing, despite the shutter speed required was much longer with a green filter.

So these are the stacked image, the first one is an average of the blur:

This one is much better:-

Sunday, February 12, 2012

20120212: Testing the 127mm Maksutov with the trapezium

First of all, the Mark-X tracks very well even without a counter weight, it means that the Carton motor is delivering plenty of torque.

Secondly, the Maksutov snaps into focus, and star images were well formed.  The trapezium is well resolved even at low power (75x with my 82 degree Japanese Widescan Type III), and it's a very ice view with my Nagler 13mm!

By placing in the Lumenera Lu070M, I could see quite a lot of nebulosity when the transparency improves just a bit... the sky is foggy tonight.

I have examination the inside and outside focus pattern and found the collimation good.  I just need a planet or the moon to really verify before I proceed for a solar filter for it.

20120212 Sun

Baader 3.8 filter ready to be used and we got sunshine!  The first shot is taken with my Ranger at prime focus, with my DIY reducer.  I've to stack a blue filter with a green filter in order to be properly exposed.

Higher power imaging is why I'm going for 3.8 filter, so I pulled out my 5x Powermate to take the following shot, only a green filter is used:

They are from AR1416, exposure was 1/60s with zero gain.  I'd say Baader 3.8 is really superb for that purpose, I'd definitely want even faster exposure!  It seems like if I were doing that with my 127mm Maksutov at f/23.6, I will be getting 3000mm focal length.  That should yield faster shutter than this setup which is 2400mm focal length at f/34.3.

Encouraged, I'll see if I have chance to test the 127mm Maksutov with planets tonight, if it's proven with good quality, I'm going to make a 3.8 Baader for the Maksutov as well!

Finally, since my Canon 100-400mm f5.6L also has 77mm thread just like my Ranger, so I've moved that Baader 3.8 there to have a shot with my Canon 450D:

Friday, February 10, 2012

Cloudy day exercise: motorizing a Maksutov

First, I've to find a place where I can mount a motor.  The screws at the back were for collimation, and so I cannot use them.  The whole focuser shaft is a moving part, so I cannot fix it there.  I might use the visual back but then it's a bit crowded there.  So I've chosen to install a plastic plate via the dovetail bar.  It's a great fit since I use a file to fit in exactly, the plate is fixed via the mounting screw of the dovetail to the OTA.

The original owner has installed a timing pulley there on the focuser shaft but the screw was a little bit too long so that it has to be tightened excessively in order to engage the pulley, so I've installed a plastic ring to make it an easy fix.

So you see the plastic plate and the timing pulley installed.  On the other size you can see the Rigel Quick Finder base installed via the threaded hole originally for a finder.

The first proof-of-the-concept prototype was done by using blue tack and a simple rubber band, backlash is crazy but then it works.

On searching my tool boxes, I found a thin belt which should work better than a rubber band, and then I also fixed the motor via some metal wire...  I should find a thicker belt and a better mounting method in the long run, anyway, this is how it looks like:

 Finally a short video to see how it works out:

The whole setup costs nothing, since I have all the parts at home.  The most expensive part is the DC geared motor while the plastic plate, the pulley and the belt were all very cheap.  The hand controller is from my JMI NGF-CM focuser, so it's shared with no additional cost.


Further improvements:

I wanted the whole setup to be removable and can be placed back easily, so I've enlarged the mounting screw hole to a slot so that the whole thing could be taken out easily.

The above pictures tell the whole story easily, the big white pulley was left on the focuser shaft to serve as an oversize focusing knob.

Wednesday, February 08, 2012

High Power Observation or Photography

This is my new high power weapon:

With 1500mm native focal length, it's going to replace my Ranger with 5x Powermate (2400mm effective focal length).  The first thing that I will need to do is to test this Maksutov on the stars at high power to see if it works well at high magnification.  With this scope, I can always use my 13mm Nagler to yield 115x which is about perfect for planet/lunar observation under normal situation.  I can also sell my 7mm Japanese Ortho together.

If sky condition allows, I can always use my 2x Tele Vue Barlows to get 230x with my Nagler.  And for imaging, it also yields f/24 which is good as well.  Using extension tube should kick the magnification a bit higher and it is do-able since this scope uses moving primary as focusing and it should accommodate the extension tube.

Once its quality on high power is confirmed good, I will then make a solar filter for it!

It's a bit longer than the C5 but still very portable, on the other hand, it's still light enough for my Mark-X.

I shall also motorize the focuser and it should be hard.  Tentatively, I will fix the motor via an extension plate from the dovetail.


Despite the poor weather, I pointed the scope at a remote building to see how it works out.

First is a shot at prime focus, despite the poor seeing (aperiodic blur could be seen on the monitor), fine detail could be resolved:-

Then, I've taken another shot at 2x, I'd say that I'm impressed by this little scope.

I didn't check the collimation but I bet it's close.  I've downloaded the instruction for collimation and I'm sure that I will try to fine tune it.

Monday, February 06, 2012

Cabinet clearing sales

Package deal: $999 HKD takes them all! 

Individual items price reduced, all reasonable offer will be entertained, just don't want to waste all these stuff.

Generic Chinese ball head, good quality, rated at 4kg, but I decided to keep it first, sorry.

Shoestring FCUSB, virtually new never used in the field, ask for $400 HKD. Control and power your JMI focuser via your USB port. 

SkyAtlas 2000.0 Deluxe Version, ask for $200:-

And the inside, a pen is placed along side to see the size, it's really a good visual reference!

Next is a 70mm doublet (f=500mm) mounted and with 77mm thread, suitable for macro imaging which brings the closest focusing distance down to less than 500mm. Ask for $150 HKD.

Celestron Nexstar mount parts, the gears were still available at $100 HKD as shown below, the bigger one was about 6" in diameter and the smaller one was 5".

JMI 2" -> 1.25" compression ring adapter, $100 HKD (SOLD):-

A finderscope base, virtually new, it's good for you to swap your finder between scopes, ask for $50 HKD (SOLD):-

Never used JJC EC-2 Eyepiece Extender for Canon EOS DSLR, $30 HKD (SOLD):-

Another custom machined 2" to 1.25" adapter, it's pretty heavy and could be good for balancing light weight 1.25" eyepiece and heavier 2" eyepiece. With two locking screws for added security.  Ask for $50 HKD.

Originally for my Gitzo G1415 when I lost one of the spikes on the legs, so I still have two remain. I've sold my G1415 and now they're sitting idle... very hard to find in Hong Kong and even the distributor refused to order them for me. Ask for $200 HKD.

A small 7-14x monocular, good quality for this size, ask for $50 HKD.

GOTO Mark-X mounting plate with counter weight, ask for $80!  The gray mounting plate was sold and is not included.

Free stuff when purchase all:

One of those screw type cases was sent as free gift already.

Saturday, February 04, 2012


自從賣掉 Solarmax 40 之後,好一段時間沒有再拍攝太陽了... 後來好不容易才找出十多年前買下的 Thousand Oaks Type 2+,再加上今日的科技,拍出來的算尚不錯,但當然無法跟之前用 Herschel Wedge 來比拼。

幾經測試,把一塊細細的 binoculars objective 貼在一塊平價 1.25" 藍色瀘鏡上,變成一個 reducer 可以一次過拍出 full disc,心裡再次感到興奮!

後來發現,原來那塊 Thousand Oaks Type 2+ 已經有幾百個 pin-holes,心想必定要把它換掉,否則難以再有興趣拍下去。在出現眾多 pin-holes 之前,Thousand Oaks Type 2+ 用來目視其實效果不錯,因為成像是橙橙的,人人都愛看,也比較喜歡這顏色。

正當我打算重投太陽攝影之時,我心想性價比最高的當然就是 Baader white film solar film,特別當我想拍攝高倍的太陽黑子,所以我特別訂購了 density 3.8 的型號,方便用更短曝光拍更高倍的照片。我買了一片 A4 size 的,回來自己再剪裁。我亦買了一個 77mm 轉接環,再把 Baader film 貼上去,再接上 Ranger 專用的 lens shade,結果就是一套易於裝拆的白光拍攝濾鏡!

把 Thousand Oaks 放在一旁,盒子用作存放 Baader filter 了!



Friday, February 03, 2012

FS: Worm driven slow motion control block

As shown, it has four pairs of M8 threaded holes spaced by 35mm (Takahashi style) to attach your equipments. On the bottom side, it has six M6 threaded holes and a free 3/8" adapter is included for attachment to 3/8" camera tripod.


The manual slow motion control knob is included as well.

Asked for $59 USD shipped for the above, paypal.

Option one is available at $25 USD extra, it is a 5 RPM DC geared motor, you may use it as an electrical slow motion control, you can simply reverse the polarity to reverse the direction.  It's compatible with any JMI focusing motor controller, or you can DIY yourself at very low cost.


Option two is available at $30 USD extra, it's a Japan made dovetail saddle (Vixen style)

This slow motion control block could be used for taking panorama, serving as the DEC axis of any existing mount like Astrotrac, etc.  Or to be used as a simple EQ tracking platform when it's tilted up.

Thursday, February 02, 2012

Sun related special events in 2012

1. 日環食

日出: 5:41am
食甚: 6:06am (5-6 degrees above horizon)
復圓: 7:16am (20 degrees above horizon)

Chance is very slim, anyway, worth to have a look, even consider it as a deep partial eclipse.


1st contact: 6:12am
2nd contact:  6:30am
3rd contact: 12:31 noon
4th contact: 12:49 noon

Chance is much better given the sun is higher in the sky and the longer duration.

昨天訂了一塊 A4 size 的 Baader Solar Film (density 3.8), 希望再一次拍攝太陽而不用受那塊十幾歲的 Thousands Oaks 折磨!

Wednesday, February 01, 2012

2012-02-01 Short Exposure Imaging

This is to test the tracking of my Mark-X but since the polar alignment is just rough by using my Android phone to point to north and adjust to the latitude of Hong Kong, so I don't expect much.

I was using my Canon 200mm f2.8L, I've taken a series of shots at 15s each since my home sky was very bright so that I cannot do longer.  Stars remain pinpoint and it's a good sign.  On extending the exposure to 30s by lowering the ISO reveals some trail, and it's not unexpected and I guess careful polar alignment will fix the problem.  Having said that, I don't think I should remove the possibility to adjust the trimming capacitor further.

While I'm still downloading DeepSkyStacker, I pulled one of those JPGs to adjust level and crop the following:

Once the downloading finished, I shall try to stack the raws. 


Canon 200mm f2.8 wide open, ISO 800, 15s, 14 frames: