Wednesday, July 05, 2017

20170704 Jupiter

Very poor seeing after a small thunderstorm, so just to test the new motorized  focusing solution.






1247 (UT), C5 with 2x barlows... the direction of the wind could be seen easily.

My Teclast has its bluetooth dead, I have to use another notebook for image capturing.

I've tried to use a USB hub (powered) to add a bluetooth dongle plus the ASI, but then it won't have enough power to drive... I guess the powered hub is not really powered.

C5 motorized focusing

The Nexstar mount is not something very solid, and on focusing, the image will shake.  Motorized focusing is a good solution.

I believe a few pictures are better than words, basically, this is a N20 type DC geared motor, plus pulley and belt.





Here is a short video to show the end result, also to demonstrate the backlash of the system.


I will probably add a pulley on the focuser shaft to provide a better coupling.

Sunday, June 11, 2017

20170610 Jupiter

Transparency 7/10, seeing 4/10.

C5 with 2x barlows, ASI 120mm


1412 UT, I've aligned by Rigel with the C5, hopefully will make future alignment faster.

Still wonder if I shall keep a C5, or go for a smaller refractor?  I don't know indeed.

Tuesday, June 06, 2017

20170606 Home@Walnut Jupiter

Cloud come and go, it's just crazy to do imaging like this:






I waited for so long just to align the mount with Jupiter.

I waited for another cloud gap for *brief* collimation.

And then I waited very long to capture a prime focus one, taken at 1401 UT:-


And then I realized the cloud amount was reduced, so I wait to capture with a 2x barlows, taken at 1410 UT, no more detail could be shown:


Moving cloud could imply poor seeing.


It's far more comfortable to shoot indoor!

Thursday, June 01, 2017

A new project: resuming Home@Walnut observation

It's raining today, and thus it's probably the end of the three consecutive clear nights.

Last night I setup my Nexstar + C5 in the old location where I observe indoor, and it's workable.  So, I should begin the migration, i.e. to move all my gears there.  I shall move one of the plants to my office, and then the rest of the plants will be placed on top of the dry box.

Another project is the motorize the focuser of my C5.  Previously I was thinking to sell it, and replaced it with my modified FD 300mm 2.8, but then it's no good at high magnification and so I will keep my C5 and further enhance it.

Tentatively, I will use one of those small motors, add brass gear on the focuser, and then drive it like the Sky Adventurer.  Let's see.

Wednesday, May 31, 2017

20170531 Home@Walnut testing of the 328

I did the final modification by introducing a short back tube of 2" diameter, it was fitted exactly from the rear lens of the 328 and the 1.25" adapter.  So, if that could not eliminate the internal reflection, it is then the intrinsic issue of the 328 optical chain, nothing to do with my modification. Therefore, I call it the final modification.


That tube looked really dark.....

The first test was conducted visually with a Canon 2x extender before a 1.25"diagonal, plus a 20mm eyepiece.  The resultant focal length should lie between 600mm to 900mm.  That is effective magnification of 30x to 45x. 

The moon is very contrasty and sharp!  Free of any false color, so I am encouraged.

Here is the first shot:


It seems okay, but the experienced eyes will know there is something wrong.   Adding a 5x powermate confirms that it sucks:






The contrast is very low, a signature of internal reflection.

Later on the same night, when Jupiter reached my window, I tested and confirmed that internal reflection was reduced, but it still exists,virtually no detail could be detected.

That modified 328 should be reserved only for imaging of DSOs.

Tuesday, May 30, 2017

20170530 Dragon Boat Festival Imaging

Again, I went back to that playground last night.

No wind tonight, better seeing... I guess around 6/10.

I setup the Nexstar in the wrong direction, I thought it will work, but then it fails to track properly, in short, it tracked with exactly opposite direction.  I believe two points alignment would do, but since I do only solar system alignment, so it won't know unless the initial position is fixed.

At first I guess there might be something wrong, and I redo the alignment but things kept on wrong.  Finally, I reversed the mounting direction of the tube, and thing got right by then.

There were no visible bright star on the sky due to the heavy light pollution, so I don't have any good target for collimation, I couldn't use high power diffraction pattern on dim stars.  So I just randomly picked a star, defocus a bit and collimate briefly with it.

I setup my scope where there were many flying insects, and my head was buried in the plants during alignment, so bad.  So I really have no mood on doing good collimation or focusing.

Moon at prime focus, 1319 UT


Jupiter with 3x barlows, 1330 UT, 150% resized


Jupiter at 1330 and 1332 UT, C5 with 3x:-



Nexstar mount, C5, 3x GSO barlows, ASI 120mc camera with my trusty and cheapy Teclast tablet.

Monday, May 29, 2017

20170529 Short imaging session


Quite windy these days, so I brought only the Ranger for this fun imaging session.


The moon is setting, so this is just a prime focus shot, taken at 1222 UT.


And we have a 2x shot, of the Jupiter, taken at 1228 UT.


Finally, push up to 5x, i.e. 2400mm focal length, taken at 1236 UT.

Using the Ranger is much easier for this Nexstar mount.