Tuesday, October 28, 2008

DMK 21AU04.AS with Asus Eee PC

I got a chance to try out an Asus Eee PC 900 which has an Intel 900MHz CPU, 1G memory as well as 16G SSD storage. Since it is so small and portable like my aging Sony Vaio U3, I wonder if it is a good computer for field usages as an amateur astronomer. Therefore, I pulled out my DMK 21AU04.AS to try out its performance.

The Asus Eee PC is a great success. I believe that it is so attractive because of its price, portability and performance. It has created a new class of computing device which people now call it a netbook. Of course, with a fully functional operating system like Linux or Windows XP, you can do a lot more than web browsing and checking your email box.

The model which I had tried is selling at $3xxx HKD (i.e. around $400 USD) and so it's very attractive indeed. It has three USB 2.0 ports so that you can hook your camera to it, be it a cooled CCD, or a ToUCam Pro, Meade DSI, Lumenera or TIS DMK/DBK/DFK. You can also use it for guiding camera, and you still have one or two ports left for devices like Shoestring GPUSB and to control your mount.

While the built-in battery is decent, but it is by no means enough for a whole night of usage. And here comes another attractive thing for amateur astronomer... it accepts 12V power input, and that's simply great. You can directly use your Sealed Lead Acid battery without any transformer, that means portability and it is also very energy efficient.

For guiding purpose, there should be no problem since you can install Windows XP to it, and many popular software will work like PHD guiding, etc. The USB bandwidth requirement is no big deal for guiding.

What interest me most for this test is those bandwidth hungry equipments, like a fast frame rate camera. The CPU of these netbooks is not fast in today's standard, and the SSD is not very fast as well. In my test, I used 640x480 which is the highest for my DMK 21AU04.AS, and I can get as high as 25 fps. And this is also the fastest frame rate that we can get with this setup. Using software ROI of IC Capture will not help for this kind of slow CPU, for the extra CPU cycle required for cropping will further degrade the frame rate.

So, given a 60 fps camera, is 25 fps enough?

Yes, I would say.

For planet imaging, you cannot use shutter faster than around 1/30s unless you are using sub-optimal sampling. For most of the time when I use my scope at f/20, f/30 or even slower, 1/15s with moderate to high gain will be the most appropriate, that implies that you can use 15 fps at most. So, the Asus Eee can do it.

For solar imaging, if we are targeting surface detail, we can easily go faster than 1/60s (actually, 1/500s is not uncommon), and so you can still get 25 fps at most. This left something to be desired, but it's still use-able, not too bad. If we're targeting prominence, we will use as slow as 1/30s or even slower shutter, in that case, the Asus Eee can do without problem.

Finally, if you're using slower ToUCam Pro which you will use 10 fps for most of the time due to the compression, the Asus Eee can deliver what you needed, and there's nothing to give up.

However, since I already got my Sony Vaio U3, I will not buy an Asus Eee at the time being, and my work horse camera is a DMK 31AF03.AS which can give 1024x768x30 fps and thus the Asus Eee is clearly insufficient, not to say that it lacks a 1394 port. My notebook hunting continues...

Goodbye DBK

I just passed my DBK to a local friend yesterday night.

I was selling my DBK since I found that I don't really have a serious scope for planet imaging. I consider 8" to be around the minimum to be really a serious planet scope. However, what I have is just a C5 and so I better leave it to someone else who can push it to the limit, use it more properly.

The DBK really shines. The first time I used it with my C5, it outperformed nearly all my old C8 shots taken with a ToUCam Pro. So, if you are really serious about planet imaging, do get one!

If I still want to capture some planet images, I can still use my monochromatic DMK, or my ToUCam Pro - which I still have two at home. :-)

Monday, October 27, 2008

C mount lens as guidescope?

Before I moved to a DSLR, I have tried a couple of prime C mount lenses for some testing deep sky imaging with my DMK, but now since I already bought a DSLR, I am wondering how can I use these C mount lenses effectively.

The longest C mount lens which I had is a Cosmicar 150mm f3.2, and I believe that it's fast and long enough to guide my longest DSLR lens which is a Canon 200mm f2.8L! Given the Cosmicar is so fast, I believe that guide stars are readily available especially when used with a monochromatic DMK camera!

Time to really test this concept.

Goodbye Baader CaK

The filter is now packed and ready to be shipped.

I found that I didn't use it enough for the past days, and actually, I found what attracted me most for the Sun is H-alpha. H-alpha can penetrate through (thin) cloud by overexposure, and you can get prominence at least, of course, it's not possible for surface detail and that's the case for CaK as well. With the poor Hong Kong sky and my very limited time, I would rather give it up at the time being.

The Baader CaK is very good and it has a very special property that it can be scale up very easily with your scope, and there's no other filter which can do something similar. By pushing up the aperture, there're always some surprise waiting for you to discover. Therefore, I would like someone who is more hard working to take over this. It simply wants a better home that my equipment cabinet.

Sunday, October 26, 2008

20081026 Sun (H-alpha and CaK)

Seeing is 3/10, transparency quite low at 4/10.

Telescope: Borg 45ED II
Filter: Coronado Solarmax 40 with BF10 / Baader CaK + APM Herschel Wedge
Camera: DMK 31AF03
Mount: Meade LXD55

The sun is very silent today, no active region and nearly no prominences. We're still somewhere in the solar minimum.

1503 (GMT+8), H-alpha:-

1508 (GMT+8), CaK:-

Saturday, October 25, 2008

20081025 Sun (CaK)

Seeing sucks, I would say it's 1/10, transparency is undefined, cloud keep moving really fast and never stop. I'm lucky (patient?) enough to have a 6s gaps, and here we go!

Telescope: Borg 45ED II
Filter: APM Herschel Wedge + Baader CaK (with ND filter)
Camera: DMK 31AF03
Mount: Meade LXD55

1336 (GMT+8):-

Friday, October 24, 2008

Lunt Solar Systems (the obstruction)

We were told that there will be no central obstruction, and today I found pictures of the filter from their website:


Yes, there's no central obstruction, but there *are* obstructions. Of course, this is kind of expected for the bigger models, however, this is not what I have expected before.

Having said that, their 50mm filter seems a real winner in terms of uniform illumination and bandpass, and it is a huge step ahead of competitions. Without the obstruction, the contrast is way better as well. And for the bigger filter models, we shall wait and see.

Equipment re-organizations

If you have been do astronomy for more than a few years, you will know what I mean.

The History

I started with a Celestron C90 (actually, a pair of 10x50 binoculars) with a camera tripod borrowed from a friend. I soon realized that I need a finder, and after getting a finder, I soon realized that I need a real mount or else I couldn't find a target easily, once I lock, the target lost. ;-)

After getting the mount, I realized that I want more field. A wider field eyepiece is the first step, but then the next step is to replace my C90 with a wide field refractor, so it comes my Tele Vue Ranger. This is the scope which I really used, it goes with me for overnight hiking, wild camping, etc. I even take it down stair to have some quick look, I guess that I have found what I really wanted, not until...

Aperture fever! You got it! My Ranger is my real first lover, I would say, so I will never sell it. I go for a Celestron C8 which is about the biggest that I can move around! That's really a great scope but it certainly wants a bigger mount, so I bought a Giro with Tech2000 drive to do planet imaging! Indoor planet imaging is fun, so much fun that I soon become in a serious lack of sleep. Other than imaging, I still love visual observation the most. Giro is too heavy and so I bought a Unistar mount, I can even go hiking with my C8 now. That was a very successful move. And then I found that I hit some bottleneck, maybe it's due to altazimuth tracking or indoor seeing condition. So I went for a LXD55... But then I found that the real bottleneck was time and energy.

Life Style Change

Life changes... I got two kids and then I soon found that I don't have so much time now, so I downsized from a C8 to a C5. I no longer need big mounts, so I sell my Giro + Tech2000, and the LXD55 is fine enough with a C5 to do some occasional indoor imaging. I don't have much time to sleep, so I couldn't keep up with indoor planet imaging. Instead, I went to the sun. White light, Hydrogen alpha, and then a Herschel wedge for the best white light, and then CaK... And I found portability is the single most important thing so I went for a Borg 45ED II... Very small really, but for the sun, pretty enough.

To push the envelop, I bought a DMK for narrow band solar imaging, and it's really powerful and fun! I also bought a DBK for planet imaging, too.

Life continue to change

I found my permenant lover? Right now I would say that's certainly the sun, but what attracted me most, is still deep sky visual observation, while I couldn't afford the time, nor the heavy gear, I still want to see how should I move on.

On the other hand, DSLR imaging seems interesting and do-able. Let's see how it moves on.

Thursday, October 23, 2008

Soldering work

Conducted some soldering work a few days ago. If you have any equipments which require power in the field, you will probably need to do some soldering work yourself.

First up is a field notebook transformer, it can provide various voltages from 12V which is readily available from field sources like Sealed Lead Acid battery. My transformer failed a few months ago and after close inspection, it was found that the fuse inside the original cigarrette lighter plug! To simplify the whole thing, I had removed the plug and installed two alligator clips there so that it can be attached to a Sealed Lead Acid battery directly! Don't worry, there's another fuse somewhere and it won't burn my notebook. However, with these clips in place, the whole setup is simpler and more portable.

Next is a power supply cable for my 1394 hubs. I have a cable made with 9V battery interface, but then the native voltage of 1394 should be 12V instead. So, I bought a cable which has a 2-pin style socket in one end, and I've installed two alligator clips on the other end. Therefore, this cable allows me to connect a Sealed Lead Acid battery to nearly any plug - and I've got so many these kind of plugs from different transformers, for example, to any notebook which is 12V native, to my LXD55, and any other things.

Very neat and convenient.

Sunday, October 19, 2008

20081019 Sun

Seeing was no good like 2-3/10, transparency is great today at 7/10. The active region is basically gone, what we have is just remnant.

Telescope: Borg 45ED II, close up with Tele Vue 2x
Camera: DMK 31AF03.AS
Filter: Coronado Solarmax 40 with BF10
Mount: LXD55 on my Gitzo G1415

1333 (GMT+8), surface detail shot, prominence pushed processed:-

1334 (GMT+8), prominence shot:-

1338 (GMT+8), 2x barlows added:-

1339 (GMT+8), 2x barlows added:-

At least we have some activities!

Saturday, October 18, 2008

20081018 Sun

The sun remains basically silent with the exception of a few small and subtle active regions. In terms of prominences, it's slightly better. Seeing was 2/10, transparency ranged from 2/10 to 6/10, depends on the moving thin cloud.

Telescope: Borg 45ED II
Camera: DMK 31AF03.AS
Filter: Coronado Solarmax 40 with BF10
Mount: LXD55 on my Gitzo G1415

1258 (GMT+8), this shot is taken through cloud, by pushing up the exposure:-

1259 (GMT+8), this shot has some thin cloud moving, so they're averaged out by stacking:-

1300 (GMT+8), this one is taken without thick cloud:-

Saturday, October 11, 2008

20081011 Sun

I missed good weather! Today we have plenty of sunshine! Seeing is less favorable at 3/10, I would rate it. Transparency is 6-7/10, very good in our standard.

Telescope: Borg 45 ED II
Filter: Coronadao Solarmax 40 with BF10
Camera: DMK 31AF03.AS
Mount: LXD55
Focuser: JMI NGF-S

Full disc surface detail, full disc prominence (normal + pushed) were taken.

1335 (GMT+8), surface detail centric exposure, prominence push processed:-

1337 (GMT+8), surface detail centric exposure, prominence push processed:-

1338 (GMT+8), prominence centric exposure:-

1339 (GMT+8), this big prominence is relatively dimmer, so I pushed the exposure to pick up the dimmer part:-

And then a Tele Vue 2x barlows is added to push up the image scale, and a 3*2 mosaic was attempted, finally a closeup of the dim but big prominence was also taken. The mosaic was basically failed, they cannot be stitched together after processing:-

1347 (GMT+8), that prominence again, close up:-

The lower part of the mosaic, consisting of two parts, this is the best of the batch:-

The middle part of the mosaic, consisting of two parts, just as record:-

The upper part of the mosaic, consisting of two parts, just as record:-

Next, I pulled out my C5/PST setup for close up...

1401 (GMT+8), very poor contrast, part of the aperture blocked by the wall:-

1404 (GMT+8), very poor contrast, part of the aperture blocked by the wall:-

1408 (GMT+8), 2x barlows added, very poor contrast, part of the aperture blocked by the wall, and seeing did not support this image scale at all:-

Friday, October 10, 2008

Selling my DBK

Don't get me wrong, the DBK is superb! So, why selling it?

First of all, originally I planned to buy the DBK for two purpose:

1. Planet imaging: it's obvious, since it makes no sense to use it for solar imaging, especially in H-alpha

2. DSO imaging: I want to try if a DBK works out well with C mount lenses, or with telescope plus strong focal reducer - a strong focal reducer will work since the CCD is very small

However, after all these months, I found:

1. Planet imaging: it's really superb! My C5 shots taken with the DBK can kill my C8 shots taken with my ToUCam Pro! So, why selling it?

It's because I have no plan to upgrade in terms of aperture. While the C5 can do something nice, but it's just not serious enough, and so I would rather leave it for those who has a bigger scope.

2. DSO imaging: Now I've a Canon 450D and this is simply more portable and easier to use than a DBK which requires a notebook in the field.

Therefore, I would rather give it up at the time being. And for planet imaging, I will go back to my monochromatic camera, like my DMK 31AF03.AS or my DMK 21AU04.AS, color or not, is less important.

A new standalone autoguider

First of all, I've zero relationship with the vendor and I just come by their product announcement and found them worth to introduce:


In short, it's something like a small and compact, non-cooled STV with the price tag of a second hand ST4! A standalone autoguider has been a dream for SLR/DSLR imagers, and I believe no one would love to do manual guiding for more than 10 minutes! Nowadays when you want to stack, you will easily need to guide all night long on the same star for the whole night, boring and exhausting indeed.

A notebook with a webcam could be a solution, but then they eat up battery fast, and of course, it's far more bulky and heavy than a standalone autoguider.

They have a promotional pricing for pre-order, but of course, we can always wait until we have real user experiences before going. Your turn.

Monday, October 06, 2008

When the bright side is hidden

When the bright side is hidden, the dark side becomes the bright side!

Canon 450D + 200mm f2.8 at f2.8, tripod mounted without tracking

Saturday, October 04, 2008

20081004 Sun

We have a typhoon around, but the sky is not completely covered, and of course, the cloud is running fast. I got a 20s gap for surface detail and around 15s of non-completely covered gap for prominence.

1452 (GMT+8), prominence shot, exposure pushed to penetrate thin cloud:-

1454 (GMT+8), surface detail shot:-

1455 (GMT+8), prominence shot, exposure further pushed to penetrate thin cloud and show dimmer detail:-

Telescope: Borg 45ED II
Filter: Coronado Solarmax 40 with BF10
Mount: Meade LXD55
Camera: DMK 31AF03

Seeing is 2/10, transparency from 1-5/10.