Thursday, June 26, 2008

Automatic Exposure Bracketing

I've tried to use EOS Utility to do automatic exposure bracketing last night.

Basically, EOS Utility does not support exposure bracketing by itself. It just allows you to setup interval shots with fixed exposure settings. However, you can do exposure bracketing like this:

1. Setup exposure bracketing (AEB) in your camera, say for -2EV to +2EV
2. Setup interval shots in EOS Utility
3. Fire

And then EOS Utility will do exposure bracketing essentially. For example, if you want to take 6 shots with exposure bracketing, you will need to set the number of shots to 18 times (i.e. 6 * 3) in EOS Utility.

I found that this setup required a lot of battery power. My notebook can run for 2 hours but with this setup, it lasted for only around 1 hour. And the camera also sucks a lot of power as well, much faster than used standalone. I guess it's because of the active transfer of images between them.

But from the experiment last night, I found that there are some random errors on my setup. I guess it's probably due to the fact that I am using a USB 2.0 PCMCIA card instead of a built-in USB 2.0 port. My old Sony Vaio U3 does not have one, it only comes with those older USB ports and it's now only to provide power. It works finally, but then I've to find a sequence in which it will work, like to boot up the machine first, plug the PCMCIA in, and then plug the power cable to the old USB port to the PCMCIA, and finally connect the camera and start the camera power. I really don't want to buy a notebook before the trip.

Wednesday, June 25, 2008

Automating the Total Solar Eclipse Setup

After listening to the talk by the Hong Kong Astronomical Society of Hong Kong, as well as the comment from Cloudynights solar forum, I believe that I shall concentrate all of my time for visual observation. For most of the part, I shall be using my Canon 10x30 IS, and then to use the Borg 45ED II for higher power visual observation. For the Borg 45ED II, I plan to use a 2x barlows with the 13mm Nagler, that means it will give 50x with more than 1.6 degrees field of view. It will be easy enough for tracking, but then still gives like 1mm exit pupil.

For that matter, I shall automate the Canon 450D + Canon 200mm f2.8L + 2x Kenko side. I shall explore more of the EOS Utility, and I guess it's great enough to use exposure bracketing to capture a variety of exposures.

And in case anything went wrong, I shall not fix anything but to look with my eyes alone!!!

Thanks for all the advice, yes, I believe visual observation is the king. If I were to look at photographs, I don't have to travel.

Tuesday, June 24, 2008

Naughty boy?

My friend finally told me that he wanted to keep his 5" achromat, frankly, it's expected. For this price, he better off keeps it himself. Of course, I would let him keep it and I just told him, if one day he wanted to sell it again, he should contact me first.

After that, my mind swing to something else nearly immediately. Another friend is selling a Borg 101ED, and it's of course a far better scope. It's smaller in aperture, but its far higher in quality. It will be useful for deep sky work, solar and lunar, as well as planets at high power. And more importantly, it's also lighter and usable on my TG-SP II! It won't be great, but it will work at least unlike that 5" achromat. However, it's more than 15 times in terms of price.

I would hold myself, since I have been spending too much these days for the solar eclipse trip, it's no good to keep doing so. Desire is always unlimited, so to exercise self control is the only way out.

Monday, June 23, 2008

Notes after the total eclipse talk

I've attended the talk organized by the Hong Kong Astronomical Society yesterday afternoon. I asked myself whether I should be late for this one since I really wanted to capture a few solar shots before going, but finally I did go there on time.

Here are some notes that I shall take notice:-

1. We should go for the "red channel" for custom, prepare a list of items to be declared, don't risk going through "green channel"

2. I shall still bring my Solarmax, in the hope to capture the first contact with prominences, and as a preview of totality, where to look at those prominences

3. The Borg will be used for high power observation during totality, I shall remove the Solarmax and re-focus at least 10 minutes before the totality

4. I shall buy a small folding chair again

5. Give up the C mount lenses exercise

Friday, June 20, 2008

Total Solar Eclipse Setup

First of all, it's the polar alignment. The Takahashi TG-SP II does not come with a mechanism for polar alignment. I've a V-adapter specially made for Hong Kong, but for overseas trips, I need to use the Manfrotto 410 head to provide the fine adjustment. I've asked a local friend to make an adapter plate so that I can mount a polar scope there for polar alignment. For a small mount like this one, I believe that a polar scope is usually fine enough without the need for drift alignment.

This is the computer. A computer is nearly a must in today's astrophotography setup. You will need a computer to control the exposure of the camera, to will want a computer to help the focusing. Of course, all these could be replaced by dedicated hardware, but a computer is definitely helpful.

This is a Sony Vaio U3, and it's pretty slow in today's standard. It features a Crusode 933MHz CPU with 512M memory. It's small and portable as you can see with this side by side photograph with a JMI hand controller for motorized focusing.

I'll use it to control the exposure of my Canon 450D, it now supports direct control of exposure including BULB exposure without the need of any special cable. I'll also use it to control my DMK31AF03.AS for solar imaging. Notice that this slow notebook can only support up to around 10fps only, but then portability rules for overseas trip. Finally, I will also use the DMK for deep sky imaging as well, together with a couple of fast C-mount prime lenses.

This is the setup. In this photograph, I'm trying to show the location of the counter weight. This is a very small counter weight, but then as you can see, it's enough to balance a camera with a lens, as well as a small telescope with H-alpha solar filter! The TG-SP II is so compact and well designed that it's not just small by itself, but it also requires less counter weight. The reduction of counter weight is done by using the motor as part of the counter weight, and the scope mounting is very close to the RA axis. Counter weight is a big part in an equatorial mount, it usually takes up 3-4kg of your total setup weight, but for this small mount, it is less than 1kg and it's enough for most cases.

Let's talk about the imaging setup. For white light, I will use a Canon 200mm f2.8L with a Kenko 2x Teleplus, of course, I will also need a white light solar filter which I will show in the later photographs. 400mm focal length together with a Canon 450D will give a solar disc bigger than 700x700 pixels in size. And with the outer corona, the field size will be big enough to cover everything. And it's still manageable by the small TG-SP II.

For H-alpha, I will use a Borg 45ED II. The Borg is equipped with a JMI NGF-S to provide fine focusing. Camera will be a monochromatic DMK 31AF03, again the solar disc size will be slightly smaller than 700x700. I hope to be able to capture some special moments before the totality, and even the partial eclipse with it. The solar filter is my Coronado Solarmax 40 with BF10.

I have used a third party ring for my Canon 200mm f2.8L, without using it, the balance point would be different for different side of the meridian. This small ring fixed this problem, and it also allows changing the orientation of the camera. Notice that this shot is taken with the Hong Kong V-adapter rather than the Manfrotto 410 head.

This show shows the cameras end. The Canon 450D is connected to the computer via USB 2.0 interface, and the DMK 31AF03.AS is connected via Firewire.

This is to show the relative location of the dovetail to the mount. You can see that the Canon side is heavier than the DMK side.

The whole thing showing the computer as well. I hope that I will have a table in the observation location, but I know it's not going to be real.

The front end again, showing the thirty party ring for the Canon lens, and the Borg is connected to the dovetail directly, I used this mounting hole instead of the one on my focuser because it allows better overall balance.

Finally, the white light filter is attached for another shot. The filter is a Thousands Oaks Glass Type 2+, this is originally acquired for my Ranger many years ago, now it's useful again.

This setup will also be used at night for wide field imaging. We will have two nights there in the observation site and I hope to be able to do something there as well.

For the Canon side, the Kenko 2x will be removed for deep sky imaging requires more tracking accuracy that I would prefer to do it at 200mm at f/2.8 rather than 400mm at f/5.6, since both 400mm and the slower photographic speed demand more accuracy than my TG-SP II can provide.

For the Borg side, the solar filter is removed, and a 9mm adjustable illuminated reticle from Meade will be used for manual guiding in case required. This can also be used for drift alignment.

Finally, here is another version from facebook:-

Mounting ring for Canon 200mm f2.8L

Just got a third party mounting ring.

I tested the whole setup again, and the balance issue is completely fixed. Balance point is the same for both side of the meridian now.

The setup consists of a Gitzo G106 tripod, a Takahashi TG-SP II mount. I'm still using the good old Intes dovetail mounting plate since the new one from ScopeStuff has mounting holes which is recessed too deep for the mounting screw head to a degree such that the mounting screw cannot sit all the way inside the socket. In short, I need to buy shorter (around 1cm) 1/4" screws in order to use this new and longer dovetail. A Borg 45ED II is mounted by the socket on the tube rather than the focuser to reach good balance. A Canon 450D with a 200mm f2.8L is used, and they're mounted by that mounting ring.

There's no place for the Konica Minolta Z5 for video taking for that old dovetail since it's too short. I tried to put a ball head on the counter weight side of the setup, but I have no suitable screw for that purpose. The screw head is too small for that hole.

Wednesday, June 18, 2008

Telescopes with DSLR

This is a series of test with my DSLR and telescopes, as well as the method of the couplings.

Telescopes used: Borg 45ED II (f/7.2), C5 (f/10 and f/6.3), Tele Vue Ranger (f/6.86)

DSLR: Canon 450D

Coupling: 1.25" nosepiece + Canon EOS T-ring and EOS -> 2" nosepiece (ScopeStuff)

The exposures are fixed at 1/10s at ISO 200 for the Borg, taken on a tripod, and 2 second timer to reduce the shake. Live View with 10x is used for focusing and it's truely useful.

This is taken with the Borg 45ED II at prime focus, the coupling used is 1.25".

This is taken with the Borg 45ED II at prime focus, the coupling used is 2". To my big surprise, the whole field of view is brighter, not just the field edge. I don't expect it's so dramatic, I even re-do the exposures to ensure that I've done everything correctly.

Now we switch to a C5, the exposures are fixed at 2 seconds each at ISO 200:-

C5 at f/10 with 1.25"

C5 at f/10 with 2", notice that since the baffle tube of the C5 is smaller than 2", and actually, it's very close to 1.5" and thus, the increase in brightness is very minimal.

C5 at f/6.3 (with reducer), 1.25" coupling with the 1.25" visual back.

C5 at f/6.3 (with reducer), 2" coupling with the 2" visual back, but this time, the increase in brightness is not negligible.

Since the 2" visual back is longer than the 1.25" visual back, the reduction factor is slightly stronger since the focal reducer is placed before the visual back.

Finally, this is taken with my Ranger at prime focus. I have no choice for this one since it only has a 1.25" focuser. To my little bit of surprise, the image quality is quite nice. Diagonal is not required to reach focus, as oppose to visual observation.

Borg 45ED II, SS EOS 2" adapter, Canon 450D

Good news is that, no extension tube is required for infinity focus.

The image is sharp, no noticeable chromatic aberration at bright targets. I shall try again during day time.

I've also tried to add an extension tube to reduce the minimum focus distance, it works, however, the whole thing is getting too long to be used easily.

Next experiment would be to try it out on the sun with a Herschel Wedge, and also my Solarmax 40/BF10, and maybe also on the moon. The JMI NGF-S works very nicely together with the draw tube of the Borg, focusing is both rapid and accurate.

With a 2" nosepiece, the connection is firm and rigid.

Tuesday, June 17, 2008

ScopeStuff stuff arrived

They arrived. Local insured mail is troublesome, and the post office mentioned that for security reason, there is no delivery service. I've finally fetched it during lunch hour. The nearby post office is not "secure" enough and so I'll have to take a bus for 10 minutes traveling, and then walk back office afterward for around 20 minutes. Troublesome especially during this rainy season.

I first unpacked the EOS T-ring, it's made in Japan as indicated from the box, it's well made and quite heavy as you pick it up. This ring consists of two parts, the outer part contains the interface to the EOS mount. I took a camera mount cap to office to see if it's a good fit. Yes, it's a perfect fit. And this ring is connected to a T-thread ring via several small set screws. With this configuration, the inner part can be common to any camera mount, and the added benefit is that, you can rotate the camera with respect to the inner ring, but then I don't think it's very useful?

Next, I unpack the 1.25" T-adapter, actually, it's just a T-thread to 1.25 nosepiece with filter thread. I plan to use it with my BF10, and also maybe my Ranger, or any 1.25" only telescopes.

Then I unpack the 2" EOS adapter. It was sold for nearly double from another vendor, so I went for this one instead. I want to use it with my Borg, and maybe my Sky90, as well as my C5. What makes it different from the above combination is that, it didn't go through the T-thread, i.e. one side of it connects to the EOS mount, and the other side is a 2" nosepiece. That should reduce vignetting, since T-thread is smaller than 2". This adapter is also threaded for 2" filter. When I unpacked it, to my surprise, it actually consists of the same T-ring as above! But there's one major different, and it's also why it's so different is that: I said the above T-ring has two parts, now, the outermost part which connects to the EOS mount is the same, but then the inner part does not produce T-thread but instead it's a very nice machined 2" nosepiece!

So, I ended up to have two identical parts, but anyway, it's still nice for it brings convenience, you don't have to remove it and re-attach it everytime.

Finally, that a 8.5" dovetail plate. It's Vixen GP compatible, it's made from solid aluminium and it has a couple of holes and slots pre-dilled to allow different mounting rings, etc. No screws were included in the package. Two of the holes are threaded, and I guess they're 1/4". There are three other holes which should accommodate 3/8" screws and the screw heads can be recessed inside. There are also two other slots like the above 3/8" holes and this adds flexibility. I will use this one to mount my Borg, my Canon as well as my KM DC there side by side.

Monday, June 16, 2008

Nexstar Parts

Removed all these things from the Nexstar 5 mount (not i, not the latest version, but the very original). If you're interested in any of them, let me know.

It includes the hand controller, the motors with encoders, the gear drives, some washers. Everything work perfectly except the PCB which is faulty.

20080616 Sun

I took half day of annual leave today, not for the sun, but for my daughter Almy. She has her teeth fixed by the dentist, and she needed to take a rest (after quite heavy anesthesia) It's very cloudy.

I did try to setup my Borg + SM40/BF10, but the condition was so bad. I missed the best moments. Just got a very short and messy video clip:-

BTW, this is how I extend the small Borg to reach the sun which is in a poor angle during summer:-

This is impossible for anything other than the small and light weight Borg 45ED II, anything else would be too bulky, heavy and dangerous to put it this way. This is a good reason for me to stay with a 40mm filter.

Sunday, June 15, 2008

20080615 Cloudy day sun

It's cloudy, I didn't even setup any telescope for the observation. All I did was just to use my 450D and the Canon 200mm with 2x to shoot. Filter is Thousand Oaks Type 2+.

1513 (GMT+8):-

Friday, June 13, 2008


This is the first time I played with a RAW file, the RAW produced by Canon 450D cannot be open directly from Photoshop CS2, and therefore, I use Digital Photo Professional bundled from the camera to open the file. I did nothing there but "convert and save" it to TIFF. TIFF is an lossless compression format, supporting more than 8-bit. Since 450D supports 14-bit now, so by saving it to JPG, you lost some signal already.

Then I open the TIFF from Photoshop. To my surprise, the image is tack sharp! It's just taken by the kit lens hand-held! Previously, the images are found to be less than very sharp, even with the 200mm f2.8L, now I know the reason. The JPEG file produced by the camera always leave something to be desired.

Therefore, I believe that we shall use RAW whenever we're doing something serious. And I'm very sure that astrophotography would require that absolutely. Next time when I shoot the sun or the moon, I shall try RAW instead. Deep sky imaging needs RAW for sure.

Thursday, June 12, 2008

Astronomy during busy days

The moon was hanging outside last night when I arrived my home at around 10pm something, the sky was hazy, and the moon was too bright to do anything. We got cloud, big and small, thick and thin. It's just not the right sky to do astronomy.

Who will try to setup the equipments under this kind of situation? Yes, I'll! To me, setting up my equipments is a very nice experience by itself, I don't have to expect good results, I don't have to wait for the best conditions. Whenever I got chance, I will want to do something. It is especially true when I'm doing all these inside my home. All I will need to do is:

1. power up the LXD55, move it close to the window
2. open the window
3. put the scope there, attach any camera, and done

As most of us will agree, having new gear will be another big motivation. Believe it or not, new stuff even as small as a new memory card, or even a new adapter will bring you joy. Astronomy is quite a complicated hobby, you always have so many adapters to fool around, so it's always nice to try out different combinations before you do something serious. And therefore, those sub-optimal skies are best used to test equipments.

I tried out my Canon 450D + Canon 200mm f2.8L last night, the level of chromatic aberration is very low, less than 1 pixel I would say, and it's contrasty and sharp too. Remember the sky was pretty bad.

Who said auto-exposure and auto-focusing won't work? It works for the moon at least, but yes, it really won't work for anything else except probably only also for the sun.

Wednesday, June 11, 2008

20080611 Moon

The sky is not very clear, it's a bit hazy but acceptable.

Mount: Meade LXD55
Camera: Canon 450D at ISO 100
Exposure: Auto-focus, auto-exposure (spot metering)
Lens: Canon 200 f2.8L + Kenko 2x Teleplus

This is to test the sharpness of this lens, however, the hazy sky is the limit. There's still rooms for improvement.

First one is saved in JPG(M), so it's smaller in size, single shot, crop and processed:-

Next one is saved in JPG(L), again single shot, crop and processed. I found that JPEG nearly cannot stand any processing, noise will simply jump out. I'll need to learn how to play with RAW asap:-

The next two shots were taken with slightly longer exposure, to show the hazy sky:-

DIY Motorized focusing

Just got a couple of small gears and pulley from here:

This is a pretty nice supplier for the components, other surplus sources should be checked as well, but for smaller motors (3mm shaft) like those I had ordered like half a year ago are quite hard to find. The above supplier is nice since they had no minimum order amount and the shipping cost is reasonable, for my order, it costs only $104 HKD shipped, and it's already the cheapest source I could locate.

I will use the pulley or gear, together with a belt to drive focusing knob via a DC geared motor. The JMI hand controller will be used, and a mono audio cable jack will be the interface, and so it's basically plug and play. By cutting a mono audio cable into two, you can have interface plug and cable for two motors.

I plan to glue the motor onto the 2" visual back, or maybe using those hose clamping to fix it in place. Let's see how it works out. I guess it would take 2-3 weeks to arrive.

Additional Remarks on 15th of June: the items were sent on 11th of June, expect two to three weeks for the delivery and then I will begin my work!

Additional Remarks on 17th of June: the items arrived, well packed, fast and good. I shall try to fit them on my mini dc geared motor tonight. It seems a good fit judging by my eyes, and the pulley seems nice and what I have in my mind. The motorizing project should be quite close now.

Daily solar snapshots

The sun is so dynamic that I really want to capture a snapshot everyday. But like most of us, with a day time job, it's really a hard thing to do.

With that in mind, I started to investigate if I can have a remote controllable setup via Internet. If that can be done, I could do it during lunch break at office, to control my setup at home. After a lot of fine tuning, basically the setup is ready. By using "remote desktop", you can control the whole setup via Internet easily. To solve the pointing issue, a webcam with baader filter can be used as a remote finder. Focusing can be done cheaply via a Shoestring FCUSB together with a JMI NGF-S. T-max tuning is harder, but we can always leave it untouched after fine tuning once. Finally, I gave up this project due to safety reason. I've two kids at home and the unattended setup might be too dangerous for them.

There's another possibility. With my newly acquired 450D + 200mm f2.8L + 2x, I can capture the solar disc in white light (Thousand Oaks Solar Type 2+) hand-held! Given that I can do it so easily, and with a solar disc not too small to track sunspots, it's perfectly easy and do-able during lunch break.

That would be great if some manufacturers to come up with a blocking filter specially designed for DSLR lenses. If that's available, H-alpha is also possible. Of course, without this "dream product", I can still do H-alpha with my Borg 45ED II, and even CaK. I shall try out the Borg 45ED II based setup once the adapters are ready. Hand-held is my target mode of operation, to minimize the setup and tear down time.

With just 325mm of the Borg, it should be as easy, but then the 90 degree diagonal will make hand-held harder than straight-through. However, with just a 10mm blocking filter, the field of view is more limited, yes it could cover the solar disc and have quite a lot of rooms left, but then you need some more field of view for easier searching.

Once the gears are ready, time for experiment.

Tuesday, June 10, 2008

Tele Vue 8-24mm non-click stop zoom (Chinese)

這是我好幾年前寫的一篇用後感, 而事實上, 經過好幾年的使用後, 最終我也把這個目鏡賣掉。但直至今天, 我仍覺得這個目鏡相當不錯, 但它的最大缺點是失光比較嚴重, 而視場也不夠闊。失光問題, 對於細口徑和高倍的觀測實在不利, 而近年來, 我亦把自己的儀器 downsize 了。倘若方便勝於質素, 而閣下亦使用較大口徑的望遠鏡時, 這目鏡仍不失為一個好選擇。

Tele Vue 8-24mm Zoom 使用後感

我使用了這個變焦目鏡已超過了一年的時間,回想起當初考慮到底變焦目鏡是否可取時,我發覺當初做的決定是非常正確的,因為自從我買了這個目鏡之後,它總會在每一次的觀星活動中陪伴著我,簡直可以說是為我的 Tele Vue Ranger 找到了一個終生伴侶!

變焦目鏡一向給人的感覺就是光學質素差,並不適合在天文方面使用,價錢也貴,同時把它們和定焦目鏡比較起來,品質也比不上。但隨著科技的發展,這已經不是絕對了,相反,我發覺 Tele Vue 8-24mm Zoom 比起一般平價定焦 Plossl 來說,實在有過之而無不及,甚至和貴價的 Plossl 比較起來,如 20mm Tele Vue Plossl,也不會輸蝕。

這個變焦目鏡,當設定在 24mm,並配合 Tele Vue Ranger 來使用,已經可以提供兩度有多的視場,對尋找天體來說,已經相當足夠;若把它設定到 8mm 時,它所提供的倍率亦可達 60 倍,若加上 2x barlows,觀察行星亦足夠。我亦常常把它和 Tele Vue 5x Powermate 配合一同使用,使得其倍數範圍可以由 100 倍至300 倍那麼有彈性;有時我亦會把它和 Orion 2x Shorty Barlows 來使用,倍數範圍則可由 40x 到 120x。

其光學性能可以在這個例子看到:曾經有一天晚上,大氣穩定度極佳,那天是我第一次看到土星的 Cassini Division,那時我是使用 Tele Vue 5x Powermate 來達到約 120 倍。當天晚上,我亦清楚的第一次看見木星的大紅班,並看到有八條以上的雲帶,而更重要的是,我所使用的只是一支 70mm 口徑的望遠鏡!我所指的清楚看見,是指我甚至不用 averted vision 也可以看見,同行的朋友也看見!同一天晚上,也是我第一次看到獵戶座星雲是扇形的!不幸的是,那天晚上我沒有帶同其他定焦目鏡來作比較,但看到如此好的成像,也讓我知道這個變焦目鏡一點也不會叫我失望!自此之後,我的定焦目鏡很多時候也被我留在家中,惟一幸免的只有 32mm Sirius Plossl,因為它能提供最大的視場。但有時候,我也發現 32mm 也會被整夜的留在目鏡盒之中。

把變焦設定在 24mm 時,AFoV 只有約 40 度多一點,對於現代目鏡來說,實在比較窄。但因為我還沒有太多使用超廣角目鏡的關係,我覺得絕對可以接受;若把變焦設定在 8mm 時,AFoV 有約 55 度,有人說在這時候,這個目鏡的質素會變差,但我並沒有發現這個問題。變焦的能力實在方便非常,例如當我尋找東西時,我可以降低倍率以擴大視場,一但找到了,可以立即增加倍率直至效果最佳為止,而無需轉換目鏡,而只需要輕微的再對焦!


變焦目鏡在深空天體觀察時亦非常有用,因為我們可以使用低倍來尋找天體,當找到天體後,我們亦可以調整倍數以控制其 contrast 和構圖,這是定焦目鏡所不能做到,除非你有很多,很多定焦目鏡。許多時候,你會發覺因為天體的本身和大氣的情況,你需要不同的倍率來觀察,這時候,也正是變焦目鏡發揮其身價的時候。

這個變焦目鏡體積比一般 32mm Plossl 要大少許,亦重少許,但它卻能夠代替數個定焦目鏡,使得整套觀測組合更為輕便。現在,我經常只會帶一個 32mm Plossl 以提供大視場,變焦目鏡和 Tele Vue 5x Powermate 以提供高倍。

Monday, June 09, 2008

20080609 Sun (and Moon)

Cloudy basically, but there's some very clear gaps. They are not very big, but enough for snapshots. This is taken hand-held when I took my kids to play outside:

Camera: Canon 450D
Lens: Canon 200mm f/2.8 with Kenko 2x
Filter: Thousand Oaks Type 2+ (also a Kenko UV)

1125 (GMT+8):-

I didn't use the highest solution setting, so the solar disc image is smaller.

I believe that by removing the (protective) Kenko filter, and by using a tripod and the image can improve a bit... also seems like my Thousand Oaks have some pin-holes, that they are numerous enough to a degree that it might affect contrast.

Additional one at around 17:00 (GMT+8):-

Got chance to shoot again, this time was done indoor via the extended dovetail and the binoculars L adapter to put the Borg 45ED II all the way outside the window, transparency was no good, with a misty layer on the upper atmosphere, I would rate it 3-4/10 at best and there was so much cloud floating around. Seeing was like 2-3/10, better than none.

The solar disc was again quiet, with a small filament, plus a few small prominences.

Camera: DMK 31AF03
Telescope: Borg 45ED II
Filter: Coronado Solarmax 40 + BF10

1618 (GMT+8):-

1619 (GMT+8), cloud was averaged out by stacking, so the detail is not sharp at all:-

BTW, I did make Jelly with Alby, and then make Almy to sleep, and then helped Alby to have her writing exercise while waiting for the cloud break! Not bad, right?

Later I went to another playground with my kids again and I saw the moon, this time, taken hand-held with a 200mm f/2.8 Canon 450D at prime focus, four frames stacked:

Auto-focus, auto-exposure, this fast lens is really nice! Nothing bad even when compared with a telescope.

Friday, June 06, 2008

Planning for the solar eclipse trip

For the solar eclipse, I will use the following:-

Mount: Nothing but the TG-SP II, latitude adjustment will be using a Manfrotto 410 head, polar alignment will be done with a third party polar scope attached to the 410 head, tripod will be a Gitzo G106 or maybe a bigger one, still thinking

Power of the mount will be from the USB port, or a 4AA rechargeable battery pack.

Video and Photography:-

1. Video: I'll use a Konica Minolta Z5 with a 2G SD card, that would allow more than one hour of continuous recording at 640x480x15, I will use a white light filter before and after the eclipse. It will be used at maximum zoom.

This camera will be left untouched during the process, just as a record of the whole event, as well as, to capture the voice response of different people.

2. H-alpha: I'll use a Borg 45ED II, Solarmax 40 + BF10. Camera will be a DMK 21AU04 (with reducer) or maybe a DMK 31AF03 (without reducer), I plan to take a few shots from the very beginning of the partial eclipse, and then somewhere in the middle, etc.

I am wondering if the USB bandwidth (and also power) is enough for both the DMK and the external hard disk which I'm going to buy, got to test before the trip.

The solar disc is bigger in H-alpha especially when we have prominences. Therefore, it would be nice to capture the eclipse in H-alpha, and it should be slightly earlier than in white light, so it would be nice to record this time. It would also be nice to capture, if there's any, when the moon covers some prominences. It's better to do at higher power, and at the same time, I will need to check the orientation where the moon cuts in. Partially covered active regions could be nice, too.

All these events will be in early phase of the totality, so it won't affect (3) and visual observation at all. Again, maybe visual first and then photography as a way of detecting any of the above events could be nice! It ensures visual observation, and at the same, allow easier detection of the event, if there's any.

3. White light: I'll use a Canon 200mm f/2.8 together with a Kenko 2x teleplus, camera will be a Canon 450D, a white light filter will be used before and after the total eclipse. It will be used to capture the critical moments, like the totality, those diamond ring, etc.

For the above three, I will only be operating (2) and (3). (2) will only be operated well before the totality, and (3) will be my choice during the totality. (1) is automatic basically. I'll spend more time for visual observation than photography.

During totality, I will concentrate on (3) and visual observation. For (3), exposure bracketing should be used to enable wider dynamic range. I also wish to do a wider field shot, let say with the kit lens for over 10s to capture the background stars. Of course, I will give this up if it costs too much of my visual observation time.

Visual:- A simple 10x30 Canon IS binoculars with white light filter before and after the totality.

Hardwares are more or less fixed, some small items are still pending, some integration tests are yet to be done.

Software is the next, I mean what I will have to shoot at night during the two days in the site which is supposed to be pretty dark - at least way darker than Hong Kong sky. I'll use the kit lens to capture a few milkyway shots and that would not require carefully planning, but I also plan to use the 200mm f/2.8 to take some wide field shots. Time to look for some colorful regions and interesting targets. I know unmodified DSLR is not going to do a very good job for those red areas, so I will try to keep my target list on those other areas, like bigger star clusters, galaxy, and colorful nebula, etc.

Finally, I guess that since I'll be bring a DMK, I will also take a couple of very fast c mount prime lens to play video astronomy, and it should help especially on those H-alpha rich regions where a unmodified DSLR might feel limited.


If the weather, or whatever on-site condition prohibits the above plan, I will go back to 200mm f/2.8 + 2x + 450D combination on a TG-SP II. If even this one is not very practical, the Canon 10x30 IS is the last tool, of course, with my eyes.