Thursday, May 31, 2007

20070531 Solar Mosaic

Seeing is like 3-4/10, transparency seems high at 7-8/10, but it's very low contrast due to thin and scattered cloud, it is a killer of any good H-alpha solar imaging. Nearly zero detail can be detected visually, very bad indeed... I even suspect decontacted etalon!

Nearly zero prominence could be seen, which is very rare indeed, solar disc surface activity is low too, we could only see a few short filaments around.

Failed again, each of the below consists of two raw frames, click for full size:-

Finally, made them together despite they didn't really match:-

PST etalon module experiments

Sad news actually, could be due to low contrast sky.

I tried to use the red filters which I ordered for my Ranger and my Borg 45ED II as Cheapy-ERF but they show nothing. The solar disc can reach focus, but none of the H-alpha features could be detected.

I immediately suspect that the etalon module was over heated and thus enlarged the bandwidth excessively, but then on removing the module, I found it very cold, not even warm since it's not in the focal plane indeed.

Later observation with my Solarmax 40 told me that, the contrast of today's sky is very poor indeed, rendering nearly no prominence visible, and surface detail has very low contrast. Double stacking with the PST etalon module helped a bit, but still, it's way below what single Solarmax 40 will show normally.

So, the experiments are not failed, just could be due to poor sky, shall try again soon when the sky improves.

20070531 Jupiter

Just woke up and saw Jupiter outside, while pretty low already but that's already what I could do, for I guess I couldn't take it 10 degree earlier due to indoor constraint.

Took a few clips at 1/15s and 1/30s with different gains, I need to try out different exposure to get a taste of Jupiter since it's my first time to do Jupiter with my C5 and DMK. The last few clips are done with ROI feature of my DMK to save disk space (Registax limit too) and to make it faster when processing, still 30 fps. Seeing was terrible at 2/10 and transparent was great (8/10) despite cloud is moving around rapidly. Equipment used was C5 with 2x barlows, DMK 31AF03.

0404 (GMT+8), 1/30s, low to medium gain, overexposed, seeing 1-2/10.

0408 (GMT+8), 1/30s, low gain, best exposure control within this batch, seeing 3/10.

0410 (GMT+8), similar as above, 120% enlarged.

0413 (GMT+8): this one is overexposed, but it's the longest clip I got, 1/30s, medium gain, nearly 2000 frames stacked at 30 fps with ROI

0415 (GMT+8), 1/15s, low gain, overexposed, seeing 3/10.

0416 (GMT+8), 15s, low gain, overexposed, seeing 2-3/10.

Personally, I love the 0408 shot most among this batch, I shall try again when the Jupiter is higher in the sky.

Wednesday, May 30, 2007

My LXD55: fixing the electronics

My RA motor unit got burnt. I don't know the exact reason for that, I've three guess:

1. I powered my notebook using the same SLA battery and on some moment, the notebook draw too large a current making the voltage unstable for the LXD55.
2. I found a coil around a magnet like stuff inside the motor unit, and some wire on the coil got its plastic cover partially damaged.
3. Sudden power disconnection during a small accident

To diagnose the exact problem, I swapped the control circuit of the RA/DEC motor, and now the RA motor will move. So, the problem would be on the small PCB of the RA motor.

I heard that we can get replacement from Meade, and we can also send the whole mount back for warranty but one cannot just send the motor unit back. Sending this huge mass across the Pacific Ccean twice is not a cheap game, obviously not a viable way for me.

So, I end up trying to fix the problem myself. On disassembly, I found a chip got burnt. Electronic guru from local and Internet told me that it should be a Dual P Channel MOSFET, which is from Siliconix/Vishay with model number Si4947ADY. My friend told me that this chip, together with a 4936 forms the driver for the motors. So, I end up ordered 3 sets of these chips in the hope to fix it myself.

There is a big concern before attempting to fix it. Without knowing why the chip got fried, I'm going to fry another chip again very easily. Secondly, maybe some other components are burnt too, but they looked nice at the surface. Those were the risks.

Another concern is about the cost. I don't expect to sink too much money on this mount. I just want to see how cheap mounts work out.

Finally, there are alternatives. I found that quite many people are burning their LXD55 in different parts, that means I can get replacement parts second hand. Some people marked up quite a lot for the components, and some people sell them very reasonably. Maybe these are better path. I would probably buying some of these as well, since it is a not so reliable/durable system.

The bottom line is that, LXD55 is not a cheap mount at all, since it might not live very long. A Takahashi looked more expensive at the surface, but it delivers more performance, and much more durable, and it could end up cheaper.

So, finally, what did I do?

On waiting for the replacement chips to come, my friend has found that our local deaer has the RA motor unit in stock at a moderate price. So, I got one through him and replaced the whole unit. Of course, it works out very nicely!

A few days later, the replacement chip which I had order from the US arrived my home. So, I proceed to replace the faulty chip by myself. Surface mounted chips are very hard to solder, and since I didn't touch the soldering iron for more than 7 years. I consulted a skillful friend and he told me to buy a pump to suck away those excessive tin. With his advice, I spent half an hour and got it done. I tested the repaired unit and found that it works like before. Now, I have a backup RA motor unit!

I feel proud to do it, since now I know the whole LXD55 from the mechanical point of view after the tuning of the RA and DEC bodies, I also know it to a certain degree in the electronic view point!

Tuesday, May 29, 2007

Color camera decision

For monochromatic target like H-alpha sun and the moon, I've my DMK 31AF03 which I suppose is the best thing I could own already.

For color imaging, right now I only got a small DC, not really target for astronomy; and I've a ToUCam Pro which is good only for the moon and planets.

With my DMK, I got a few C mount lenses so that I can use, so if I go for color, I could reused those lens if the camera can accept C mount lenses. So, one of the choices would be another DMK, but in color version. The DMK performs reasonably good for long exposure, it does not require much battery, but it needs a notebook and it does not have a lot of pixels. It would be excellent for moon/planets, too.

Another choice could be a astronomy dedicated cooled CCD, preferrably to find one which can accept C mount lens, and I hope the cooling can be switched off in case electricity is not as widely available and the exposure required is not too long. However, that would be slow frame rate, the need of a heavy battery and also the notebook. That would be excellent for long exposure, but it would be hard to use in any other cases.

Finally, DSLR is the third choice. It's very portable, no notebook and heavy battery issue, however, it would require a seperate collection of lenses, and inside my mind, to build up this collection, it would take:-

1. Canon EFS 10-22mm
2. Canon EF 50 f/1.8
3. Canon EF 200 f/2.8L

With the camera body, it would mean around 16K, not exactly a cheap option. And since DSLR cannot take movie clips, this camera is not going to be useful for family functions. And DSLR means that I will want to upgrade every couple of years.

Frankly, upgrading seems a common problem among all the above 3 options. Cost aside, DSLR seems the best option for me. Cooled CCD is pretty like a waste for my current equipment (especially mount) line-up. DMK is more like for planets which I didn't do much, and still expensive and upgrade-prone.

My LXD55: fine tuning and re-greasing - RA body

With the experience I got from tuning the DEC body, I got the whole thing disassembled with 10 minutes. Clean it with the same trick, re-grease it and it's done.

I don't have to polish the bushing on the RA body, since it looked very good at the first place. It explains why the RA axis is smooth even before the tuning process.

Now, the DEC head will rotate downward by gravity when the clutch is disengaged if the counter weight shaft is not installed. Quite easy and the improvement is great.

The Sun and the Moon

These days I've no chance to take image of the sun, both due to my schedule in the afternoon and the weather pattern.

However, I got 3 or 4 chances to observe the moon these days, it's really nice actually.

For apartment dwellers like me, small scope is my only way out, and thus, the biggest targets are what I should concentrate my effort on. So, the Sun and the Moon are pretty nice target to me.

Monday, May 28, 2007

20070528 Moon with color (again)

This is my second attempt, I guess this time I shall stack more to bring out more color, and after reading some online references, I will be able to reproduce the color more faithfully.

Again, it's Borg 45ED II, with 0.5x binoviewer corrector and extension tube, so it's working at ~f/5.9 with effective focal length of around 280mm, ToUCam Pro to cover the whole lunar disc.

~1950 frames stacked, taken at 2320 (GMT+8).

Sunday, May 27, 2007

20070527 Lunar Again!

This time I used my Borg 45ED II, a 0.5x binoviewer corrector which means f/5.9 effective focal ratio, ToUCam Pro for color imaging of the full disc moon.

Exposure time is 1/500s, zero gain, and you can see, part of the lunar disc is overexposed, color saturation is stretched to try to show the color of the lunar soil at different locations. That's why I used my color ToUCam Pro again. Taken at 2232 (GMT+8 i.e. HKT), around 1000 frames stacked.

Taken at 2235 (HKT), this one has shutter at 1/1000s and low to medium gain, to avoid overexposure like the above, but this one is actually underexposed, only ~600 frames are stacked for this one. The color is very much different from the above after processing, so I wonder what's the objective way to play this color pushing game.

Compatibility test: ProGuider and Guidemaster

It's raining crazily outside, and so I could only do some small test at home, rather than imaging the sun.

Version 2.0 are used, and I found ProGuider can work with my DMK 31AF03.AS, but Guidemaster failed to open the device despite it could be detected.

ProGuider even support autofocusing, my NGF-S with Shoestring FCUSB works correctly with ASCOM driver.

Friday, May 25, 2007

20070525 Lunar Observation

After the DSX test, I setup my LXD55 and place my C5 on it... I found that half of the aperture of the C5 is blocked, so I will have to wait for some time until the moon move downward until it's cleared.

With a GEM, the viewing angle is really very limited. Even now I just use a C5, I couldn't get a good view for most of the time. Years before when my Giro is still working, I could always use a C8. Anyway, equatorial tracking is the best in terms of squeezing the last bit of quality for imaging.

During the wait, I took out my rarely used 2" diagonal, together with the binoviewer. Frankly, the eyes are far more forgiving when taking the aperture block, since I'm doing lower power only. The view is great, I found that I still like visual observation more than imaging, but the environment is just too bad for viewing alone, and that's why I'm doing imaging. So I remind myself, everytime I take image, I should have some views with my eyes, too.

Target list: deslandres which is a walled plain, close to famous features and thus overlooked to me before; Plato, for its shadow; Epigenes, north of Plato; Eratosthenes, again for its shadow; and all the way back to the south, Moretus, again for the shadow.

Equipment is a DMK 31AF03, Tele Vue 2x barlows, Celestron C5 on LXD55:-

Taken on 2253 (HKT), Deslandres, it's also called a hell of crater, for you can find Hell (the deepest one, on top left) and Hell B (the shallow one on top, slightly to the right) there, the very complex one on the bottom middle is Lexell.

One more shot taken at 2302 (HKT), notice the change of the shadow in just around ten minutes.

Taken at 2257 (HKT), on the center of the stage is W. Bond, and the deep crater on its left is my target which is Epigenes, and on the far right, it's C. Mayer which is even more attractive in this processed shot. I made Epigenes to be my target because it's very nice to my eyes with my binoviewers, but it's not as nice in this shot.

Taken at 2259 (HKT), this is a really handsome crater to my eyes, it's called Eratothenes, and it's at the end of Montes Apenninus. I didn't catch enough of 50% of its glory.

This is Plato, taken at 2255 (HKT), note the shadow. The C5 is too small to show those craterlets inside, but I guess if we got a better sky (seeing and transparency), we might be able to spot a few.

Taken at 2300, the most eye catching sight is the crater called Moretus on the middle left, immediately on its right is Curtius.

I read The Modern Moon - A Personal View immediately after the short imaging session, and it's really nice!

20070525 Evaluation of Meade DSX mount

It's a partially clear night after a series of cloudy nights. Seeing is no good, transparency is pretty great but cloud are floating around, making serious imaging impossible.

I setup my DSX mount to evaluate whether it's suitable for imaging or not. I bought it for remote solar observation and so it's important for me to see if it's good or not. My first attempt to use this mount is with Meade DS electronic focuser, but later found that most of these mounts are faulty for that port (I tried two of them), and so I gave up. But this time, I have a NGF-S driven by Shoestring FCUSB and thus it's independent of the mount's electronics.

GOTO is pretty accurate, even to the moon. So, it's great for remote operations. Tracking is fine to the eyes, but on imaging, you can see it's actually shaking. I did it at 325mm at prime focus with a DMK 31AF03. I'd say it's marginally acceptable for this setting. Here's the result:-

It's pretty blur indeed, but marginally acceptable somehow, if you're not very demanding.

I pushed it up with a 2x and the blur is too much, I didn't even try to take any shot with this configuration.

I'd say, I'd want an even lower power scope with this setup remotely, to avoid those shake.

My LXD55: fine tuning and re-greasing - DEC body

The QC of these mounts could be extremely bad, and the grease is of very bad quality, people even called it glue. So, on filing the rough edge and to re-grease it, will be great way to improve this mount.

In order to do the above jpb, one will need to disassemble the mount and the best site is the "Astronomy Boy" website:-

Astronomy Boy

And here I also include my own adventure. To remove the DEC body, you only need to remove the two bolts from the front. However, to disassemble everything, you probably need a wrench:-

Disassembly was harder than I think. The first retaining ring below the setting circle was held so tightly so that I failed to remove it without suitable tool. At last, I bought a new wrench to do the job. I hope that I did that earlier since I had already ruined some of the black paint of that ring, but it didn't hurt functionally, I was lucky. You can see that wrench in the photograph above.

After that ring was removed, I saw those cheap transparency plastic rings which were supposed to be bearings/washers. The has some telfon replacement available, but they were not cheap, so I planned to keep the originals. If I was to pay more, I would go for a better mount.

The next hardest part was to remove the DEC gear from the DEC housing. I nearly soak the whole thing with WD-40 for several days in order to take them apart.

I found two bronze bearing/bushing which were not found in the CG5, maybe those were the enhancement of the LXD55 to make it work for the 10" SNT. They were nicely made, unlike the other parts.

I cleaned up all those greenish glue like grease, home detergent work very nicely. I heard that mineral spirit work even better, but I didn't test it myself. I had polished all the bearing surface carefully afterward, sand down those protruding parts and rough locations (how cheap the quality!!!). I could see why it was so stiff before. And during the polishing, I could firmly believe that the mount would be far better after all these work, since there were too many trivial problems which had not been fixed by the manufacturer.

After cleaning and polishing, I tried to re-assemble the mount. The DEC gear again was very hard to be pushed back into the DEC housing. I found that was because the paint inside the DEC housing was not done evenly. I wonder why they would paint the interior of the housing!!! So, I sand away those paint and it fits rather nicely then.

Then, all the parts were ready for re-assembly. I apply some lithium grease on the bearing surface before re-assembly, then I turned the moving parts to ensure that they were smooth before putting the next parts in. So good, they were far more smooth!

Wednesday, May 23, 2007

My LXD55: The tripod

Here I begin another serial of articles about my work horse mount, the Meade LXD55.

LXD55 is basically a Chinese made Vixen GP clone, with added GOTO system based on Meade Autostar. It's not particularly good quality, actually, it's quite cheap internally. I've some more articles following to show how cheap is its internal, and also how to improve it.

I bought mine from an online friend from Alaska, since Meade factory outline on ebay does not allow direct ordering from non-US location. To save shipping cost, I asked my online friend to throw away the bundled tripod for me. I know the tripod is of low quality, and it does not worth to ship it at all. The ebay price is very fine indeed, and it's probably the cheapest GOTO GEM in the world.

Since I didn't get the tripod, my first project is to find one suitable for this purpose. I could buy a Vixen but there's other options available. I've a Gitzo G1415 which I used with my Giro mount and I found it very compact and light weight, and what is more important is that, it supports my C8 pretty well, so I believe that it will do the job to hold my LXD55.

All I need is to custom made an adapter for it. The G1415 has a top mounting plate with a 3/8" screw on it, if one want a center column, this plate is to be replaced with a center column. To me, a center column is absolutely not needed for astronomy purpose, and to maximize the stability, it simply shouldn't be used. On removing that mounting plate, you can see it's held by something like a compression ring:

Here is the dimension of the adapter, together with a photograph:-

With some measurements, I know I need an adapter like this:-

* 8.5cm outer diameter
* 10cm flange diameter
* 2cm flange thickness
* 7cm bore hole diameter
* 2cm bore hole depth
* 2.5cm overall height
* 1cm * 1cm AZ pin width

And here's a final product made by a local friend. And so we put everything together, we have:-

The counter weight tied to the leg is due to a poor angle from inside my home, if you align the mount briefly to the north point leg, it's not needed. Actually, if one extends the tripod fully, it won't be required, too.

And more to follow, like how to fine tune the mount, clean it and re-greasing. Have a search for "My LXD55" later.

Saturday, May 19, 2007

Indoor testing of DSX-90 mount

I've conducted several tests on the DSX-90 mount.

First of all, I tried a blind alignment, i.e. to level north and to do autoalign. The automatically chosen alignment stars appear to be in right direction, and then I made a GOTO to the sun (as a special asteroid), and it's in good accuracy.

Second test was to test its capacity, I placed my C5 there, carefully balance it and it moves flawlessly. Sounds like a good portable platform for me, in case photography is not needed, and in that case, my Takahashi TG-SP II would fit in.

Sounds like my Unistar Lighter has no suitable use case now, this DSX is not much heavier than the Unistar Lighter but it can track and it can GOTO.

Upgrading the Tele Vue Ranger

Tele Vue Ranger has excellent optics at its age, once considered to be the reference standard at its own class together with its brother, the Tele Vue Pronto. However, we have got many small apochromatic refractors come out to the market these days, Tele Vue finally discontinued their Ranger/Pronto.

My Ranger has served me extremely well, from wide field visual observation, to medium power planet/lunar observation. When I bought my SM40/BF10, it also served me as an excellent solar scope, too. I've some special relationship with it, it's not my first telescope (which is a C90), but I used it the most, I didn't use my first telescope as much as it is. I would say, it's my first telescope which I really use and learn astronomy.

So, it's normal to think of how to upgrade it. Several vendors are providing 80mm f/7 APO lens in cell to the market, to name two, say William Optics's APOGrade lens which is selling at around $400 USD, and another vendor in ebay, selling a lens in cell at around $300. People reported that the William Optic's one is better in terms of quality.

So, one will say, Ranger is a 70mm instrument, so how to use a 80mm lens with it?

Yes, Ranger is a 70mm f=480mm telescope and the lens is going like 80mm f=560mm. Ranger has a 77mm thread lens cell, and therefore, one can make a small extension tube to make up that 80mm difference in focal length, and with a 77mm male thread to mate with the original lens cell! Of course, you will need to remove the original Ranger lens first. Simple?

One can also adjust that 80mm difference in focal length to create more or less back focus, according to your needs like your imaging device, binoviewers, etc.

In order not to vignet the 80mm aperture, one can use similar triangle to calculate the light cone size before entering the Ranger tube which is 77mm at its longest. Given a 80mm f/7 lens, the light cone will be 77mm wide when it's ~21mm from the objective. Therefore, the new lens cell should at least 21mm when joining the old Ranger lens cell with 77mm thread.

To preserve the original focus travel of the Ranger, we will need the extension to be 560-480mm = 80mm and for it's longer than 21mm, it will not vignet the 80mm objective. However, the Ranger lens is recessed from the front thread, we should taken it into account. It's around 2cm recessed, and therefore, the extension tube should be at most 60mm if we want to keep the original focus travel.

Therefore, we can go from 21mm to 60mm as we wish. If we want more back focus like for binoviewer, we should make it shorter, like 21mm or 25mm to be safe. If we simply want to preserve the original focus travel, we can simply make it 60mm.

A pretty simple project, I suppose, provided that if you have a friend who can machine the adapter for you.

Friday, May 18, 2007

Mightex CMOS cameras


Monochromatic camera is pretty expensive, but this one seems cheap enough, the specifications are attractive, featuring a large 1/2" chip with high pixel count, it also supports ROI to increase frame rate at the expense of smaller capturing are, which makes it very flexible.

The large chip size will mean simple for full disc shot, no need to do mosaic.

For solar imaging since the exposure time is relatively short, especially for surface detail when the sky is good, noise shouldn't be much an issue.

If I finally go for remote imaging and didn't want to leave my DMK under the sun for long time, I'd definitely go for one. Previously, CCTV + frame grabber will be the only way for cheaper price, but now we have a USB 2.0 option at a very nice price.

Thursday, May 17, 2007

PST etalon

With the PST etalon acting as an internal module, the sweat spot issue becomes more serious.

On processing some of the newly acquired shots, I found that the images simply cannot be stitched together, and part of the reason i found is that, the image quality on one side is different than the other side, one side is contrasty, and one side is blurred.

Seems like this should be taken care in order to make mosaic. The simplest way is to allow more overlapping between frames, and cut off the blurred part.

Let's see how to move on. Any new equipments, despite they could make you more powerful, have a learnng curve with it. Once overcome, the true power can be unleashed!

Solar image processing: poor alignment

Recently, the sky was pretty bad and the transparency has been very low. It washed out the detail and resulted in very poor contrast. The example image was taken on 2007-05-14 1614 (GMT+8).

Poor contrast will make alignment very hard to do, for the registration/alignment point is not very concrete and may even disappear or smear from frame to frame, here's a stacked image under this situation:-

You can see that the image is very smooth, for the detail are smearing and averaged out each others. Finally, wavelet seems to be able to cure it somehow, but notice that the detail are wider than they actually are:-

The only solution to this problem is to choose another more contrasty feature and re-stack again, but sometimes it could be impossible.

My Herschel Wedge decision

First of all, a Herschel Wedge is probably one of the best white light solar filter one could get.

Herschel Wedge can be scaled up easily, you just need a bigger refractor, and it's durable, easy to maintain and safe.

Next, a Baader CaK filter can be used with it, for highest quality results. Then, the Baader CaK can also be used on Venus. So, it means this small piece is both very high quality and very versatile.


Red filters: last night I tried to screw the red filters on my Ranger and also on my Borg 45ED II and they're perfect fit, so now I just need to wait for a good sky to test them. Another local folk has upgraded his PST ot 70mm with a C-ERF which I sold to him a while ago.

He also uses a Meade DS mount, and even a bluetooth aircable serial adapter for remote control.

Sounds good.

Wednesday, May 16, 2007

Red filters arrived

The package finally arrived, it's not lens caps this time. :-)

They come with a nice plastic case, those transparent cases which screwed together by friction, pretty standard for filters like this.

To my surprise, the filters are with different colors! Despite they all marked with (25), but they're totally different!

One of the 52mm is darkest among three, and another 52mm is slightly lighter, and the 77mm is brightest! Seems like that I've to email them to ask why.

The two 52mm when stacked together, is good enough to serve as ERF, since there will be a layer of air between and the transmission is low enough. The 77mm one, however, is probably too light color, even lighter than the 6.5" aerial filter (to be used with a C5, cell pending).


The top line from left to right are: Polarizer, ND3 which are used with the Herschel Wedge, next is a UV-IR block from Baader, and the last one is a CaK also from Baader, to be used behind the Herschel Wedge, too.

The three red colors are what I described above, they're supposed to be the same color, but they're vastly different. They're used as ERF, I called them Cheapy-ERF in general. The dark one on the far right is a IR pass filter.

Tuesday, May 15, 2007

Borg 45ED II configuration

Since the lens cell of my Borg 45ED II can be connected directly to the 2" visual back, therefore, the whole drawtube assembly can be removed to increase the back focus, vignetting is not an issue for such a small objective.

I shall use this configuration to test the idea about using Herschel Wedge as a ERF, but then the PST-BF5 should be used for its higher transmission, I've tested a regular BF10 will not do, since it's simply too dark, it cuts too much light.

Meade DSX mount arrived

I got the mount which I just bidded from ebay, it's double boxed, and it great shape. This is a brand new mount and it's a new model I can say. It comes with a very nice cradle which is far more elegant to be re-used for other OTA.

The battery compartment is a better fit, and I can see a calculator style lithium battery inside, maybe it can keep the time by itself? But if the Autostar 497 can get it or not? I don't know. Got to check out from the web.

The fit and finish of this mount is obviously better than the old Meade DS/DSX mounts which I owned.

Should give it a test tonight.

Post-testing remarks:

1. the mount works!

2. the autostar will fetch time and date from the DSX mount, the battery is really for time keeping, great improvement!


Also tried the PST etalon with my Ranger, it won't focus without a 2.5x at the nosepiece of my mirror diagonal, and thus should be similar with a BF10.

Monday, May 14, 2007

20070514 Solar

The sun is sinking low in the sky, I just back from Silvermine Bay with my parents and also my own family, pretty tired, but still want to take some shots. Setup is my Borg 45ED II, with 2.5x corrector and PST etalon module, SM40/BF10.

Also tested that it not only won't focus without the 2.5x corrector, but also even with a 2x barlows.

AR955 (1607 GMT+8) and the newly formed AR956 (1609 GMT+8):-

Very poor contrast, strongly processed.

Finally, a failed mosaic... when the sky is poor, the contrast is hard to maintain and it's next to impossible to make mosaic:-

Sunday, May 13, 2007

20070513 Super Foggy Sky

Not just foggy, but cloud is also moving, gain has to be set very high, 1/30s.

Borg 45ED II, SM40/BF10, PST etalon, 2.5x corrector at nosepiece of BF10, DMK 31AF03... I did some visual work today, too... zero contrast, nothing like the view of yesterday... on plugging in the camera, I can fine tune the focus a bit to reveal something, but still, very bad.

very strong processing is applied, is it AR955?

Saturday, May 12, 2007

20070512 Visual Observation

This is the first time I double stack my SM40 with an internal module made from PST etalon, the contrast is superb! 0.1A difference is big enough to make a rather big difference!

To tune the etalons, I shall use the Tmax on the SM40 to adjust the internal reflection to just outside the field of view, and then I can turn the collar of the PST etalon module to get maximum contrast. Very nice indeed!

AR955 is around in the middle of the solar disc, no dark spot can be seen easily at low power (20mm with my Borg 45ED II), several very nice prominence can be seen too!

Then I remove the PST etalon, and everything back to normal, quite a lot of surface detail were gone, the image is far less contrasty... I shall say, the difference is rather huge!

It's time for me to go out now, and when I've time, I shall capture some shots with this new setup! However, to make it focus with my DMK, I shall need to place a small corrector in the nosepiece of the BF10 first.

The next step would be to use this internal module with a suitable ERF, on a bigger telescope!

Additional Remarks: The setup I used is different from PST+SM40 since we skipped the ERF of the PST, and thus the image is brighter. Notice that SM40 has built-in ERF so what I'm doing is just to sandwich the PST etalon between the SM40 and the BF10.

Also, double stacking two Solarmax filter will also mean two ERF in series. Thus, my double stacking configuration will result in a brighter image since only one ERF is used.

USB Power Cable for Takahashi TG-SP II

Finally, I've implemented my USB power cable for my Takahashi TG-SP II, I did it because I got a failed USB device and thus the USB cable can be used for this purpose.

There is nothing special for this small project, the only thing to do is to make sure the cables are correctly connected. For the wiring diagram, you can refer to the link tomy USB batter box.

A Link to my USB battery box:-

And then you may want to check out my USB power cable idea below, to see why it will and why it won't work:-

And then one should be checking repeatedly with a multimeter on the polarity and voltage in the whole process, to make sure nothing went wrong. Make sure you don't use the data cable since it could carry Vcc as well. So, refer to the wiring diagram and check each cables end to end for the pin and cable correspondence.

Finally, I plug in the USB battery box above and my TG-SP II works! And I then plug it in my computer's USB and it works, too.

Thursday, May 10, 2007

Unit finder comparison

Review of the Rigel Quick Finder and the Telrad

Background Information

Since I found that my Celestron Star Pointer (see another article) is inadequate for my C8, I proceed to search for better alternatives. The Telrad and the Rigel Quick Finder are the natural choices, I bought both of them since the shipping cost is too high if I order only one item.

I have a 6x30 finder which comes with the C8 OTA, but since the bracket cannot be removed from the OTA easily, I found it not so portable. At the same time, I'm used to use a unit finder, and that's why I go for these two infamous unit finders.

P.S: I sold my 6x30 Celestron LER finder soon after I got my Rigel Quick Finder.

The Package and the Options

The Telrad comes with a single base, variable brightness control, no battery, and 3 concentric circles of 0.5 degree, 2 degree and 4 degree. It is longer and heavier than the Rigel Quick Finder.

The Rigel Quick Finder comes with two bases, variable brightness control, Lithium battery included, and 2 concentric circles of 0.5 degree and 2 degree. The blinking reticle is a standard feature in the Rigel Quick Finder. It is shorter and lighter than the Telrad, but since it stands on its base, it is actually taller when in operation.

The switches on the Telrad is larger and better placed, so it's easier to use and more accessible. The switches on the Rigel Quick Finder are located on the opposite side when it is in operation, however, I have to say, both are very easy to use.

The Telrad uses standard AA battery and the Rigel Quick Finder uses CR2320 Lithium battery. With the Telrad, you have to provide your own battery and with the Rigel Quick Finder, you have them included in the package.

There are three alignment switches for both of them for alignment.

The Rigel Quick Finder and the Telrad at work

Both works similarly, very easy to view through, with an infinite "eye-relief". Parallax are not a problem in both of them for any person, much better than a red dot finder.

Alignment to the main optics is easy for both units, with the Telrad even easier. It is easier than the Celestron Star Pointer and also a conventional finder in a 3/6 points adjustment bracket. The switches of the Rigel Quick Finder are a bit small, especially the one which control blinking of the reticle, the rest are okay. It's alright for the weather here in Hong Kong weather since it won't be too cold, but if you've to manipulate those switches with heavy gloves on, it would be difficult, if not impossible especially for the blinking switch, but all other switches are large enough, just not as comfortable with the Telrad. Alignment of both units is easier than an conventional optical finder.

The Telrad, having one more larger (4 degree) circle, which is nice for star hopping and it is missing on the Rigel Quick Finder. In a light polluted sky, landmark stars are not always available and so the extra 4 degree of the Telrad is nice, but under better sky, the 2 circles of the Rigel suffice.

The Telrad is larger and it would be awkward to use it on a smaller scope. The Telrad is also much heavier to a degree that the balance of the OTA might be upset. The footprint it casts on the OTA is long as well. Be careful that someone might find their tube rings are hindering the installation of the Telrad due to its long foot print.

To use an unit finder, as usual, you view through the reticle using one eye and see the sky with the other eye. It seems strange and difficult, but it is easy once you try to do so! The sky look exactly like in the star chart, you have more stars or better say, more context, to look for your target. At a light polluted sky, however, an optical finder would be nicer for it provides more light gathering than naked eyes, the magnification it gives also increase the constrast of the targets by darkening the sky background. Better yet, you can augment your Telrad or Rigel Quick Finder with a conventional optical finder. Objects invisible for the naked eyes will be invisible with the unit finders, but there's a chance to glimpse it with a conventional optical finder.

Both are fun and easy to use. I found blinking reticle is not that much useful since you can dim the reticle and it serves the same purpose rather well, in my opinion. However, I guess it will be useful in those truely dark sky which is absent here in Hong Kong, ANYWHERE. Each of them have their own pros and cons, so maybe it's fine to get both of them!

Both finder has adjustable brightness control and the range is wide enough that you can use it without affecting your night vision (not tested in truely dark sky) and you can use it to locate the moon.

Last but not least, you don't have to use optical finder and these nice unit finders exclusively, you can always use both of them. But in my opinion, if you are comparing any optical finder with less than or 30mm aperture, I believe it's better to go for a Telrad or Rigel.

Wednesday, May 09, 2007

Telescope dealers in Hong Kong

Amateur astronomy is not very popular in Hong Kong, partially due to the light pollution and the air pollution, however, I would say it's more related the lifestyle. With such a small demand on astronomical equipments, it's pretty hard to find out where can we buy the stuff that we wanted. After fooling around for more than ten years, here's a list that I collected:

1. Sun Sing Scientific Co. (Celestron dealer) 日昇儀器
- Telephone: 2320-9770
- Mobile: 9361-3351 (Mr. Kwan Yiu Ping - 關耀平先生)
- Website:
- Address: 新浦崗景福街新時代工貿中心 2110 室 (Room 2110, New Trend Centre, San Po Kong, Kowloon)

He's actually an amateur astronomer himself since many years ago, however, he said that now he has no time to play any more, but he's still willing to serve fellow astronomers. He's basically a Celestron dealer, he was selling Takahashi and some other brands before, but now you can probably only buy Celestron from him as well as some mainland China imports.

I bought my C90 from him, a couple of accessories and later my C8, and some binoculars, too. He's a nice guy actually, but be sure to call before you visit, he could be rather hard to find sometimes.

2. Grand Eyes Optical (Meade dealer) 巨眼天文儀器
- Mobile: 9013-0450 (Mr. Chung Kwok Yan Antony - 鍾國欣先生)
- Fax: 29758087
- email:
- Website:
- Address: 17/F, Flat 5, Hang Sing Mansion, 48-78 High Street, Sai Ying Poon, Hong Kong.

The Meade dealer here, you can also buy Japanese stuff from him. He's selling some Taiwan and mainland China import, too. The above address is actually his home, so be sure to call before you visit. He was a very active astronomer, he's still in the game, but not as active as before as I was told.

3. Tat's Telescope Company (Vixen Dealer)
- Mobile: 9218-2440 (Mr. Ng Lun Tat - 伍倫達先生)
- Fax: 29758087
- email:
- Website:
- Address: P.O. Box 1228, Yuen Long Post Office

The Vixen dealer, you may also buy Japanese stuff from him but Vixen should probably the only brand which he will keep stock. He's a very nice guy, still a very active amateur astronomer.
He can also custom machine adapters.

4. Risheng & Brother Company
- Mobile: 9636-5986 (Mr. K.K. Chiu)
- email:

He's the Coronado dealer (also Canon), and he will also sell brands from USA, Germany or Japan, for telescope any size, camera, webcam, etc.

5. Tan14

He's not a dealer actually, but he's willing to order Japanese stuff for you and as you can see from his website, he keeps quite a lot of stock in particular Takahashi refractors. He is now *the* Japanese source for many local amateur astronomers, he can offer really good price and nice service. More like a friend than a dealer. He's also an active amateur astronomer.

Other than that, he can also make virtually any adapters for you, at very moderate price but the quality is extremely good. Highly recommended.

Sunday, May 06, 2007

20070506 Foggy Solar Observation

SM40/BF10/Borg 45ED II at prime focus:-

Taken at 1538, very poor and foggy sky, wash out every detail, no contrast at all.

PST etalon module has a good home

Adapters delivered. This time, I said delivered since the very helpful local folk even take it to my home for me. It's again very well made.

1.25" interface gas enough room for the PST etalon for both sides.

My Borg 45ED II does not have enough focus travel to eat up the length by this whole chain of stuff, but adding a 2.5x corrector at the nosepiece of the BF10 will do the job fairly nicely.

The sky is foggy, and thus I couldn't really tune the PST etalon to a fine position.

The next step is again to put the etalon module back to the PST, tune it and place it to the adapters here. And to try out with various ERF.

The big red aerial filter is passed to my friend to make a plate to lock it on the C5 objective, once it's done, a very powerful solar gun will be ready!

Thursday, May 03, 2007

Alternative mounting ring for red aerial filter

After some thought, I've an alternative approach to mount the red aerial filter on my C5, it's simply a thin metal ring like the following:-

The 3 red circles are 3 holes to be connected to the black metal cell via 3 screws, the black metal cell has 4mm width. The green rectangles are to be cut from the blue ring, which matches the two protruding lock from the objective end of the C5.

3 yellow holes are to be drilled and threaded to connect with the 3 red holes above via 3 screws. The black ring has 4mm width.

The red filter is recessed from the top of the cell for around 6mm which is more than enough to hold the filter on the objective of the C5.