20151218 Moon

Seeing was no good again due to the strong wind, it's not too bad as it will be getting warmer in a few days.

The moon was going to the edge of my observation window and thus I could only get this one, resolution lowered.

2018 (GMT+8), Ranger at prime focus.

20151216 Sun

Winter finally comes! Having said that, it means 16 degree Celcius only... it's going to drop to around 13 tonight, so wind is getting strong.

Rather nice transparency at 6/10, seeing 1/10 as created by the wind....

Reducer lens always inside the BF10 unless stated explicitly.

First up is an image taken with ROI feature, frame rate goes up to over 40 fps, but given the very poor seeing, it does not help much.  Taken at 1433 (GMT+8):-

This is what it called "skip" mode, full resolution is not used by skipping some pixels, which results in higher frame rate, but with the same field of view.

By using full resolution, the frame rate is lower and as you will see from below, the image is blurred far more by seeing.

So now the "skip" mode is even more useful than ROI. 

I found that ROI is not well implemented by SharpCap, it is not user friendly at all, one should be able to draw the ROI on screen instead of setting offset and the frame size!

The Dark Cube at Work: 20151202 Sun

After some experiments, the Dark Cube now works.  A reducer was used in order to fit the whole solar disc into a single frame, given it has 5M pixels, making it a bit small is still fine enough.  The reducer lens is just a 30mm binocular objective, dropped into the barrel of the BF10 so that it was sandwiched between the blocking filter and the camera.   The focuser drawtube of my Ranger was fully retracted, and the fine helical focuser has enough travel.

Seeing 3/10, transparency 2-3/10 with cloud around, so I only got around 200 frames to stack.  The T-max/RichView could be tuned more carefully if there was less cloud.

AR2458 on the left, a few small prominences around.

Taken at 1409 (GMT+8).

The Dark Cube: new monochromatic 5mp CMOS camera

This is the second light, I've placed a simple convex lens between the BF10 and the camera nosepiece, this is effectively a reducer.

The result is that, the chip can hold the smaller solar disc with ample spaces so that I could move the sun around while imaging.

I've set sharpcap to get 600 frames, i.e. more than 2 minutes at around 4-5 fps with full 5mp resolution.  Since the solar disc was moving around, the Newton's ring was averaged out and the dust removed too.

The file is 8.5G in size!  Transfering the file from my tablet to my PC took nearly an hour via wifi!  Crazy indeed, and I've tried to move that file via a micro SD card but then the system complains that the file system on the SD does not support that large a file! 

Registax is moving slowly...

The time stamp was not from the camera and not from the driver too, as the manufacturer said, I've to double check with Sharpcap to see if I might turn that off.  A bit annoying...

The image was a bit soft, I suspect it could be a result of:

1. bad focus, you know, I'm effectively imaging at very big image scale despite I'm working at less than around 400mm since the pixel density is oh so high!

2. poor seeing, again, due to the big effective image scale... also the relatively long capturing window will blur fine detail.  I shall check.

In summary, if I were to take a fine full disc shot, use full 5mp resolution.

If I were to capture fine high resolution detail, I should go for ROI, and that will allow much faster frame rate and then, I could freeze seeing.

New monochromatic camera, setting up

Got a new one, I guess not many people use it, it's based on CMOS which is quite risky.  I don't know if it has Newton's ring... if there is, I will use the drift and average method.

It has 5M pixel so that I no longer need to go for barlows and the chip is quite big so that mosaic work is minimized.

The problem becomes frame rate due to the large volume of data.

With my Windows 8.1 tablet, it could go up to 5+ fps when saving to the internal SSD... it drops to lower than 1fps when saving to a good micro SD card, but then I know it's due to the internal card reader rather than the card itself.

When my Eee PC, the frame rate is slightly less than 3fps....

So, the tablet will be used for imaging, and I will have to free up space from the internal SSD to store the video clips.  I was thinking to remove the android partition which I seldom use.  But then I will want to make a partition dump as backup.

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First light, since the frame rate is low, it could be hard to gather too many frames to stack, for example, to stay within a 100s time window, we could have only around 500 frames to play with:-

Note that the camera driver will insert time stamp on the upper left... !  Anyway, most of the newton's ring is averaged out except on the upper right area... I shall explore way to improve.  The amount of detail is nice, and we don't need to go for mosaic.

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To free up extra space for AVI storage, I have decided to erase the Android of my Teclast.  However, I reserve the right to go back later, so I only remove the user data partition which is around 16G in size.  Before formatting that partition, I use:

http://www.macrium.com/reflectfree.aspx

to backup the partition image, so when I need it again, I will restore that particular partition.  Actually, I have another Android tablet so I will not use that on my Teclast.  And in fact, the Teclast Android is buggy, for example, the wifi password would not be saved and I will need to enter it every time after rebooting.

By removing that partition and reformatting to NTFS, we could use it for image capturing but then I found that the drive letter than I assigned via Computer Management (Windows 8.1) will be lost every time I reboot.  After some investigations, I found that partition was set hidden.  To unhide it, use diskpart commandline to unhide... select disk, select partition, partition detail, attribute volume set/clear hidden

too cryptic?  not already for old age IT guy.

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To remove the Newton's ring, I will try to DIY a tilting device and there are some C mount extension tube from taobao, and they might be good candidate for the modification work, and it might be a good idea to sandwich a small reducer lens between the tilting mechanism so that I could have full disc in a single shot!

Before making the tilting adapter, I will try to image the sun without tracking...  i.e. just let the solar disc drift from one side of the CMOS to the other side slowly, and hopefully, the rings will be average out.

Canon FD 300mm f2.8 conversion: internal reflection

When using as a telephoto lens, I found internal reflection if there is bright light source around.  With careful inspection, it was due to a silver ring inside the adapter chain.  Therefore, I've blackened that ring, and now the problem was solved.

Tonight, I tried to use it again on the moon, and the result is very good.

Then, I placed the EOS-1.25" eyepiece adapter in, and I will need to insert a diagonal between the lens and the diagonal, the internal reflection issue comes back!  I soon realized why, it's because the silver barrel of the barlows!  On shielding it with black cover, it's all solved!

It's a good astrograph, it's a good day time telephoto lens.  However, it's not so good as a telescope for:

1. a diagonal has to be inserted, and thus, it has effective focal length of more than 900mm... so it's no longer a wide field instrument.

2. for high power observation, it's not wide to use a f2.8 objective

Therefore, I am going to sell it.

Replacement camera for my Lu055M

Since the death of my Lu055M, I had been trying my ASI 120mc on H-alpha imaging but the result is acceptable at best. I had an ASI 120mm before, but the newton's ring is too annoying so that I sold it soon. The image taken with a 120mm is great, however. I was impressed from the image on the real time screen, not to say the stacked version! I had been looking at those CMOS camera again, and I had one in mind and it features a CMOS sensor which should have newton's ring problem! The chip size is bigger, big enough to fit in the whole solar disc with my Ranger and it has 5 mega pixels and so I have no more need to make mosaic. With my Ranger which has 480mm focal length, the solar disc image would be smaller than 4.2mm but of course, with the prominences at the edge and it might exceeds the size of the CMOS sensor a bit. To elminate the newton's ring, the simplest way is to let the solar disc to drift round the sensor while capturing. Flat field might not work since the pattern of the newton's ring might change rather rapidly even if the solar disc moves a little bit in the field. Let me see how it works out, and the bottomline is that, it's going to be a fine lunar camera.

Concept: Motorized focuser for my Ranger

Formerly, I was using a NGF-S and then upgraded to a NGF-CM. But those were sold due to the exit from solar imaging, and after getting the Solarmax II, I had been looking for a JMI focuser, but so far I could find any good deal. I had bought a Event horizon focuser but then it was incompatible with the old interfacing adapter. With the recent jump in shipping cost, and the lack of good second hand offering, I am thinking to motorize the original helical focuser of the Ranger. Going up to 2" for the Ranger is not very attractive and that also lowers the motivation towards JMI focuser, too. So I will be looking for a timing belt (同步皮帶), and a suitable timing pulley (同步輪/同步皮帶輪) and DIY suitable mounting adapters. The mechanism should be better be removable, and I could engage and disengage the motorizing mechanism too. Let's see how to move on. -- At the mean time, I will to use my adapted Canon FD 328 for visual purpose, see if it is acceptable or not for wide field scanning and high power observation.

Testing of the Canon FD 300mm f2.8

This is not a good test, but this is what I could do at the moment.  Dark sky should be where it shines.

The target object is the moon, and I've used a tele vue 5x before a star diagonal to push the power up...

I found that if I keep on indoor light on, the image will be totally washed out.  It seems like the lack of baffling is the killer of the contrast.  But for deep sky imaging at darker sky, it should be no problem?

20151014 Sun

My daughter was sick leave at home, so I was there with her.  Chance to pull out my solar gear and captured this one:

Color cam is not really for H-alpha imaging... again resolution killed by the bayer filter matrix of the ASI 130mc, got to buy a new monochromatic camera soon!  Seems CMOS sensor with rolling shutter is to be avoided?

AVI converted to older format via virtualdub and then processed with Registax 5, downsized to reduce the effect of the artifacts.

20150929 Sun (very poor sky)

Just stacked, and a waste of time to further process.

1524 and 1525 (GMT+8), prime focus.  ASI 120MC.

20150928 Sun with ASI 120mc

Yes, you read it right, and I'm using a color camera to do H-alpha since my monochromatic LU070M was dead.

This frame shows the problem, the bayer color matrix ruins part of the resolution... 

As a work around, I downsize the images and here are the results:-

First up is a prime focus shot, taken at 1539 (GMT+8):-

Next is an overexposed prime focus shot, at 1542 (GMT+8):-

We have a huge prominence stretching all the way out and go back to the solar limb, what a sight!

Finally, a 3x close up:-

which is the downsized frame of the very first image of this page.

My Lu070M is dead

Today I found that my Lu070M is dead, I try to fix it but in vain.

Computers could still detect its presence, its serial number is shown too.  But then the captured screen remains all black, not even noise was shown.

I wonder if I should buy a ASI 120mm again or to let the Solarmax go.  I'll wait to see if I could find something good and cheap, first.

Meanwhile, I'll use my ASI 120mc at the time being.

Australia trip first shot 20150807 Gold Coast Surfer Paradise

This is a simple shot from the balcony of the hotel room:

Note the Omega globular cluster!

I did take longer exposure, but it didn't help much, so this one is left as a record.

A clean sky is half way to success, it's bright there but you could still do something.

20150923 Sun

Cloud moving around, so I only managed to get one single shot as below:

1400 (GMT+8), prime focus, i.e. 480mm.

Teclast x98 Air

It's a Chinese Windows 8.1 tablet, featuring a OTG port.

I have tested last night, ASI 130mc could be used without problem.

However, Lu070m failed probably due to insufficient power from the OTG port.  A powered USB hub should work, but I got to test again.

This could be perfect for webcam imaging and guiding purpose.

--

To give a little bit more background, it features dual boot so you could choose between Windows 8.1 and Android 4.4.4 during startup.  There is no hot swap between two systems unlike some other Chinese offerings.

The 64G storage was split around half-half, with the Windows side having slightly more memory.  After installation of Office 2013 (bundled for free), SharpCap, ASI and Lumenera drivers, Stellarium, ASCOM Platform, PhD Guiding, BibleWorks, VLC player, Dropbox (occupying around 6G of space), I got around 9.5G space left.

I will need a buy a fast 64G micro SD for image capturing.

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Installation Notes of ASCOM platform:

It required .NET 3.5 but Windows 8.1 has .NET 4 instead.

When I try to install .NET 3.5, the system refuses to install and after applying all the Windows Update, it success... but then it eats up a few gigabytes too.

--

Finally, I bought a 32G SD with 48M/s speed.  I will try to use it solely for imaging purpose, and upon capturing, I can take the card out, and process the files from my PC.  32G ought to be enough for one or two imaging sessions.

And then I also bought a OEM bluetooth keyboard and mouse, to be used with the tablet.  It's nicely designed so that it makes the tablet notebook like!  Best of both world, a small portable notebook, a tablet which can run all my astronomy applications, guiding, image capturing, processing, plus the android side for daily work.  The added bonus is the capacity to run Bible Works!

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To further simplify the whole thing, I've bought a OTG cable which allows direct connection to the camera:

Final form of the converted Canon FD 300mm 2.8 in EOS EF mount

This is the adapter used. It consists of a 77-58mm step down ring, and then a 58mm focusing tube, plus a 58-42mm step down ring. The flange distance is then adjustable to suit different situations.

A 58mm tube is used instead of a 42mm tube which I previously acquired, to avoid any vignetting.  A M42 to EOS EF ring with electronic focus confirm is used, it is glued together to ensure proper orientation of the tripod socket. 

A large piece of glass!

70mm refractor on the left and 300mm f2.8 lens on the right... as an amateur astronomer, we all love aperture!

My very first autoguiding exercise

The Sky Adventurer has only single axis guiding, so it would require good polar alignment to guide successfully... of course, it's rather hard to do indoor.

Finding a bright enough star is not easy too... but I managed to get one.  The polar alignment was rather off despite the target star stayed in the field for quite long, and that indicates not too bad polar alignment.  However, it did drift away slowly and PHD guiding was complaining.

Cloud moved in before I could try EQ Align to fine tune the polar alignment.

Now at least I know that my ASI 130mc and the ST4 port of my Sky Adventurer works, I will need a better night to try the whole thing again.

A small DEC motor was on order, together with some electronics, and I will try to make my Sky Adventurer with dual axis motor/guiding.  Not very confident, but why not have a try?

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For dual axis guiding, the guide scope and the imaging scope  should be on the same side of the L adapter, so the balancing side should carry something heavy as well... is that making the whole thing meaningless in that case?  The Sky Adventurer is wide field and portable!

I guess I will be taking a 200mm lens for my trip, so the polar scope should be enough and no need of guiding.  So, I will be bring a 50mm lens, a 200mm lens plus a 2x tele extender and that's all.  The 300mm f2.8 will be left at home.

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To test the concept of using camera lenses as guide scope, I found that I have to insert a 2x barlows in order to reach focus with a camera lens.  It's good in the sense that, the guiding lens is always working at higher power!  Suppose I have two lenses, 200mm and 300mm respectively.  If I use the 200mm as imaging scope and the 300mm as guide scope, the guide scope will be working at 600mm due to the barlows.  Even if I swap their role, the 300mm as imaging scope and the 200mm as the guider, but then the guiding side will still have 400mm focal length!

Sky Adventurer dual axis guiding

The Sky Adventurer features a ST4 style guiding port which allows RA guiding, but that also means it only correct PEC.  The DEC part is manual driven only, so we couldn't guide in a dual axis way.

Motorizing the DEC part is the first step, here we have two approaches:

 

The one on the left is to use an inline shaft coupler, I got one at home which matches quite nicely.  Problem is that, the motor would make the whole thing much more bulky.  The next method is the one on the right, it uses two gears, one on the original manual control knob and another one on the motor, but I got only one such gear ready at home.  I will need to buy one more and the motor could be placed below the DEC body, I will want a smaller motor in that case, and I will also need to find a way to mount the body and mesh the gear correctly.

The following wiring scheme could be used:

Guider -> 

ST4 port of my own, getting the DEC signal to drive the motor -> 

ST4 port of the Sky Adventurer

So no need to modify the Sky Adventurer, just add a "relay box" and steal the unused DEC signal.  A simple geared motor controller could be used to drive the DEC.  Too good to be true?  Best of both worlds?  Let's see... I shall start hunting for suitable parts.  We need gear with 6mm shaft bore.

Further downsizing: Skywatcher Sky Adventurer

This is a huge move again.

My GOTO Mark-X is very portable but yet, it requires a "heavy" 410 geared head, and it is rather heavy and bulky as well.  So here I go for an even smaller mount.  This mount should be able to do astrophotography and it should be able to let me use my C5 visually or for planet imaging.

First of all, the tripod that I'm going to use is a Velbon mini-white.  It is ultra-portable as you can see from the above picture on the right.  It can even sneak within a lens compartment of my Fastpack 350!  Next is the Sky Adventurer, the mount body could be hidden in a lens compartment of my Fastpack, too!  The polar wedge is lighter and easier to use than the 410 geared head, and again, could be fitted into a lens compartment.

This is what I have fitted within the lower padded compartment of my Fastpack 350 as shown above:

Upper left: Canon 50mm f1.8, plus a ASI 120mc for guiding.

Lower left: Skywatcher main body which is a self contained mount with hand controller and battery compartment, polarscope!  It even features an ST4 style guider port!

Upper middle: a Velbon mini white tripod, frankly, it's even more miraculous than the Sky Adventurer and they are also a perfect fit.

Upper right: polar wedge for the Skywatcher

Lower right: a Canon 200mm f2.8L

Also a Canon 70D with a 8mm fisheye lens

What's left is a L adapter containing also the DEC body on the upper compartment, and the notebook computer in its own compartment.  Too good to be true, right?  A simple backpack containing all the lenses, tracking mount with guiding, guider and camera!

The picture on the right is the testing setup.  It takes a Ranger without any problem and I would say a C5 is easy for this small guy with proper balancing on the other side of the L adapter.

20150427 Sun

Heard that there's a long filament these days, and I got time at home, so why not?

First up is a prime focus shot stitched from two shots at 1431 and 1432 respectively.

Then we have 3x shots:

1434 (GMT+8), this one is aimed at taking the filament and prominence in a single shot, but it's too big to fit into the field of my Lumenera Lu070M.

AR2327 and AR2311, taken at 1437 (GMT+8):-

An exposure aimed at the prominence, and it shows more detail than the 1434 shot.

An exposure aimed at the filament, and it shows more detail the 1434 shot as well.

Enjoyable short session.

Dedicated Guidescope?

I am thinking about the need of a guidescope which is important for astrophotography.

However, if you're going to bring several camera lens for different focal length, we might actually use them to guide each others.  For example, if you're going to bring a 200mm f2.8 and a 300mm f2.8, they might be able to serve as the guidescope of the counterpart with suitable adapters.

In case the focal lengths are quite different, say 100mm and a 300mm, a tele-extender might be added to make them close.  We know that the guiding accuracy might suffer if you use shorter focal length to guide longer, but that's what you have to live with when we want absolute simplicity.

Remember the good old days, my friend used a FS60C and Sky90 in that way with great success.

Conclusion is that, for relatively wide field imaging, and I know that 300mm is pushing the limit, we might not need a dedicated Guidescope.

Selling my GOTO Mark-X

It's a very great mount, high capacity, compact, precise, and the most important thing is that, it's a working piece of history, a collector's item.

But still, I'm moving to lighter weight stuff.  So here we go, if you're lucky enough to see this, feel free to make an offer to me.  I have a reserve price in mind, but why not just offer and ask?

Here is a few pictures of the mount.  First of all, the controller and the motor is not original, but from Carton which is the OEM of the discontinued Tele Vue System Mount.  The speed of the motor could be fine tuned by turning a small knob inside the hand paddle.  It supports both northern and southern operation, and it has stop and 2x mode.

On the back of the paddle, there is a detachable battery pack of two 18650 Lithium batteries.   A set of two will last for many observation sessions.  The battery pack could be attached to the back of the hand paddle neatly as shown.

So, it could be removed any time.

The black motor mounted on the Mark-X.

A U-adapter was mounted securely on the Mark-X, with one side with a worm geared driven DEC slow motion control block and GP style dovetail saddle, the other side was a 3/8" screw which allows attachment of a ball head, I will throw in a good ball head if the offer is good enough.

Another view of the mount, the mount body is very new indeed.

Finally, everything could be packed in a small padded camera bag which is included in this deal.

Thank you for looking, and waiting for any reasonable offer.  If there is no offer within a week or so, I will put it on local astronomy forums.

The Quest of a 4" refractor/astrograph: experiment and fine tuning (Canon FD 300mm f2.8)

As an amateur astronomer, I have several Canon EF adapters lying around. I found this one to be perfect for such purpose, since there are three fixing screws so that you can turn the M42 thread again the EF mount!

So the orientation of the lens could be fixed easily!   Note the pencil mark I made above in order to find out the best orientation.

QED.

Tonight, I have conducted photographic and visual test.

Visually, it's sharp at low magnifications.  I have used a diagonal by placing a 2x barlows lens in front of it, serving as a relay lens.  It could reach focus without problem.  Pushing the power will result in softening, unacceptable I would say, and it looks like internal reflection due to the extra lens elements on the rear part.  My primary impression is that, this is not a good visual telescope, and it is not going to replace my C5 therefore.

Photographically, it's great.  It's very sharp and free of any color fringes.  On pushing it with a Kenko 2x, I found that it will produce error, but of course, if I use a M42-EOS adapter with built-in chip, the error will go away, and I will have focus confirm signal too.  So, I will need to buy myself a rotatable M42-EOS adapter with built-in chip, and then the project will probably close.

Conclusion: this is a very nice camera lens, but not exactly a great telescope.  I found that my 200mm f2.8L suffers from the same problem, while the Canon 100-400mm is a great telescope, however.  Faster lens is not really good candidate for visual purpose at high power.

The Quest of a 4" refractor/astrograph: implementaton (Canon FD 300mm f2.8)

After removing that three little screws, it's still pretty hard to remove the rear part... but then I've a tool which was used when I was disassembling my PST before!  With it, it could be done rather easily!

Rear assembly removed cleanly:

The 77mm P0.75 male thread was left:

I'm getting excited!  With the M77-M58, M58-M42, M42-EOS adapters in place, we have the following compact 4" refractor with 300mm focal length!

The amount of 77mm thread is enough, on the contrary of my previous imagination!  Next, the flange distance is correctly made for EOS with a single extension tube.  This becomes a very fast f/2.8 compact refractor!  Unluckily, when all the adapters were screwed together, the orientation of the built-in tripod socket was in a bad position, I have to find a solution for that.

 
The above configuation allows infinity focus without any problem!  The built-in focuser is butter smooth despite it is a very aged lens.  Canon L series is really really serious!

To switch it into visual configuration, the extension tube should be removed, and a EOS-1.25" adapter is used.  Unluckily, the amount of optical path length is insufficient for a star diagonal.  The following picture shows how I could reach infinity focus with an eyepiece.

This is a 300mm wide field refractor, with my 20mm widescan, it yields 15x with 5.3+ degree field of view, very sharp and respectable!

To use a star diagonal, I must insert a 2x barlows in front of the diagonal, so it becomes a 900mm focal length telescope.  The exact focal length must be measured.  I must try to use it for planet imaging soon, and if it's good enough, I shall sell my C5.

Keywords: Canon FD 300mm f2.8 conversion EOS digital EF mount astrograph telescope flange distance eyepiece M42

The Quest of a 4" refractor/astrograph

This is a progress report of the following:


http://osastrolog.blogspot.hk/2015/03/4-refractor-project.html

The FD 300mm f/2.8 is still being delivered by Hong Kong Post, way slower than anticipated and it's abnormal.  Other parts arrived.

The first one is the most critical, ordered new.  It's a M42-EOS adapter with chip which allows focus detection.  The FD 300mm f/2.8 should have 77mm thread upon removing the rear aperture control part, so a 42-58mm adapter was sandwiched between the M42-EOS and a 58-77mm stepping ring.  It's rather compact and strong enough as shown below:

However, as expected, the amount of 77mm thread is a bit little since it's originally designed for filter, but now it's going to hold a lens-camera combination.

In order to create the proper flange distance, a 3-piece extension tube will be used to connect to a camera.  The FD 300mm f/2.8 will then become an astrograph or for regular imaging.  In case the combination could not meet the flange distance, an adjustable M42 tube should be ordered.

To be used in visual mode, the extension tubes would be removed, and instead, a 1.25" barrel adapter will be used, plus a diagonal which should probably make up the optical path length to allow infinity focus.

Of course, the combination above might be a bit optimistic, and might require some more fine tuning, like adding extensions.

You know, I am getting excited.  A poor man's portable astrograph and wide field 4" refractor all in one!  Even an expensive new EF 300mm f/2.8 will not be able to serve in that visual configuration without a 2x barlows as a relay lens!  Best of both worlds.