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20160326 Sun

The sky cleared up, with seeing 4/10 and transparency 7/10.

Sharpcap upgrades again from 2.7 to 2.8 this time, and it's apparently faster.

Taken at 0453 (UT), using the "skip mode", i.e. to skip some pixels in order to burst the frame rate at the expense of lower resolution:

Another one at 0523 (UT), using near full resolution (crop a bit), the frame rate is much slower, and it might result in some field rotations... a much bigger file (nearly 9G of data), but high resolution full disc shot in a single capture!

A new member

I always love my trusty Canon 10x30 IS, it's so portable and powerful... even its rubber coating was damaged by the DEET a few years ago.

I got a good deal recently on a Canon 18x50 IS!  I had always been looking for something like that, for example, I suffered from a broken Canon 15x50 IS before from ebay which costs me the return shipping cost and so much frustration!  Finally, this is a local deal which is about perfect!

IS works very nicely and with the higher power and the heavier weight, I expect it won't be as great as the Canon 10x30 IS for the stability, but the added aperture, and the far higher power is going to shine!

Longing to use it in the field!

I guess it will be a great partner to be used with wild camping trips.

--

2016/3/27 night:-

The sky cleared up a bit with transparency 3/10, I picked it up for some scanning from inside my home.

I saw nothing when I pointed it to the muddy sky.  However, after engaging the IS, stars popped up from the view, and the stars are pinpoint!  I could see the subtle color differences between stars, but then there is no chromatic aberration except on a few brightest stars, but I suspect they might be from atmospheric dispersion or effect of poor seeing.

I am pleasantly surprised by its optical quality.  High power scanning with image stabilization is just fantastic! 

20160309 Partial Solar Eclipse

My original plan was dull and boring, i.e. making high resolution H-alpha eclipse shots.  But the sky was so bad earlier this morning rendered this plan impossible.  So armed with my Canon 70D with a 100-400mm lens, and a 20 years old thousands oaks solar filter, what can I do?

I did a field trip yesterday night to see whether the location is suitable or not.

And this was how it looks this morning:-

Gave up? Not yet...

At 0814 (GMT+8), I first saw a hint of the sun...

Then at 0821 (GMT+8), it was even better

Soon I realized that I could take some images which clear sky would not allow, this was taken at 0844 (GMT+8),

Another mug shot at 0835 (GMT+8),

The sun was climbing up, taken at 0844 (GMT+8),

The sky was once cleared enough so that my filter must be used, taken at 0857 (GMT+8),

More shots with terrestrial object at 0920 (GMT+8),

Another one at 0922 (GMT+8),

The last one at 0954 (GMT+8),

Something that couldn't be done with great sky...

20160229 Sun

This is a special date, once in four years.  This is a special holiday for my daughter, and so I go out to have lunch with me.  So, I missed the normal observation time window.  By then, I can move my equipment cabinet in order to open the window of another side to capture the sun.

Using "skip" mode  which results in faster frame rate at the expense of lower resolution, 1539 (GMT+8):-

Using full size mode results in very low frame rate, but no need to do mosaic, alternative coloring scheme, 1546 (GMT+8):-

Teclast x98 Air 3G

A couple of months ago, I've backup the android partition and removed it.  The built-in drive is much faster than the micro SD (despite I've bought a faster micro SD) and therefore, much better for image capturing for the Sun and planets.  However, it has very limit space... in order to maximize the size, today I decided to remove all android related partitions.

To further free up spaces, I've mounted the micro SD to a NTFS folder and then moved the dropbox folder there.  So, I will have around 10G more space.

This is to prepare for the partial solar eclipse, as well as future imaging requirements.

20160227 Windy Night Pre-Collimation

After the arrival of the C5 Bob's knob, I installed them right away.  During the process, I found that the retaining ring of the corrector was loosen! 

Anyway, I installed the new collimation knobs one by one, and then remove the corrector altogether for cleaning.  To my surprise, the secondary was a bit fogged, and thank God that after some cleaning, it is shinny as new!  I removed the corrector entirely in the hope to find the original marker at the edge so that I could correct the (relative) orientation of the corrector.  Luckily, I found it!

Collimation with terrestrial target is not going to be accurate, so I just very roughly collimated by looking at the front of the scope, wishing that the correct was in proper location at the same time.

The sky cleared suddenly tonight, and I pulled out the Nexstar mount to do the collimation with tracking.  It is windy so I don't expect to do a full collimation but just a rough one, so that I could fine tune it within a few seconds before I do any imaging.

Pointing at the sky randomly, no star was shown basically no matter how I adjusted the focuser, and it indicates really bad collimation.  Swing to Sirius reveal a very ugly out the focus pattern, fine tuning the focus does not help but it shows an very asymmetric pattern, added with the turbulence generated by the poor seeing, I was a bit shocked.

Then I turned the focuser knob to a very out-of-focus position until the pattern was stable.  Adjust the collimation screw one-by-one, to know which screw corresponding to which direction.  After a couple of minutes, rough collimation was done. 

A good collimation is not just about correctness, but it is also about the even tightnesses of the screws.  The reason is that, if all three collimation screws were tight, it could hold much better than loose screws during transportation or even storage.  Therefore, I keep adjusting all three screws carefully, in order to tighten (not over tightening) all those screws.  Things were done within another couple of minutes.

I ended up using over 15 minutes in doing that.  Re-adjusting the focuser, the diffraction pattern is now much better!  Due to the poor seeing, for the most of the time, I couldn't see a nice diffraction pattern but then during moments of brief stableness, I could see it was quite nice.  Maybe even enough for imaging too.  I also found that background dim stars are shown.

When I was about to call an end to the task of tonight, I do a swing to M41, and it was shown very nicely.  I guess only a very minor touch will be required next time when I want to do imaging.  Last time the Jupiter imaging session was in vain both due to poor collimation (but I got no screw driver with me), and mis-orientated corrector, and now they were all fixed.

20160209 Sun

AR2497 and 2494.

Pretty good seeing, 1428 (GMT+8).  T-max tuning could be improved, however.

Bob's knobs ordered for my C5

Went out last night for Jupiter imaging, setup everything but found that collimation was off!

Too bad that I forgot to bring a screw driver.... no way to tune!

So, I ordered a set of Bob's knobs! 

I was tempted to buy compatible screws, but then I feel that I need to respect the original inventor!

I found my newly bought small camera bag could fit my C5 and the Gitzo G105!  The zipper pockets could hold eyepiece too!

I'd keep my C5 therefore.

--

Some day-back records:

A few days ago I took some solar images.

Two nights ago I went out for visual observation with my Canon 10x30, but then nothing could be seen except M42 and M45... M35-38 failed, M41 was suspected.

Last night was the Jupiter imaging session, failed badly.

20160125 Winter Sun (冰天的太陽)

Armed with a new focuser together with a clear sky, there is no reason not to shoot.

It's record breaking cold in Hong Kong, at 3 degree Celcius and strong wind, it's not bad to be able to shoot indoor.

First up is sun taken with crop mode, note the Newton's ring... 1403 (GMT+8):-

On using full chip mode, I could drift the sun around while capturing and that effectively remove the newton's ring, it's also much higher in resolution.  1407 (GMT+8):-

Click for full size.

A little adapter designed and 3D printed by a local buddy Jack Wong

The Skywatcher Sky Adventurer mount has a small polar scope illumninator, but then it has to be taken off before attaching the dovetail rail or a ball head.  It is not very convenient in the sense that 1) when the mount was moved accidentally, polar alignment could not be done without taking off everything 2) when attaching the telescope or camera, the setup might moved and then polar alignment has to be redone.

To solve this problem, a local buddy designed a small orange adapter and then 3D printed it so that the polar illuminator could be attached to the dovetail rail!

JMI NGF-CM w/DRO

I've been looking for a NGF-S or NGF-CM, but in vain.

Too great that I came across such a deal in CN classified, and better yet, the seller agreed to sell me because I had been active and helpful in CN!  It's not unexpected since there involves extra effort to ship overseas.

I'm excited, you know, this deal seems to be prepared for me.  That focuser didn't even come with a telescope adapter, not even for SCT, but I had one for my Ranger!

Solar imaging quality could be improved finally...

Finally got the tracking number, and it just left US last night:

cw796258549us

expect to arrive Hong Kong in 6-10 days, i.e. earliest arrival could be Monday.

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.

--

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.

--

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.

--

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.