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  #21  
Old 23-01-2018, 12:19 AM
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tempestwizz (Brian)
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Thanks Les. It seems the pictures in the Takahashi .pdf are the ones missing from the CelestialPortraits website document. Also that the CelestrialPortraits document is a translation of the Japanese on the Tak site. Classic Jinglish!

I was hijacked by ‘she who must be obeyed’ today, and so have made no progress. Tomorrow!

I do have photos by the way, I’ll post them when I can work out how to do it successfully. My first attempt failed.

Last edited by tempestwizz; 23-01-2018 at 12:32 AM. Reason: Add a little more information
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  #22  
Old 25-01-2018, 09:39 PM
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tempestwizz (Brian)
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Update: I’m still adjusting, and awaiting darkness again for another real star test.
My latest theory is that there are two points of focus that need to be brought together with the spacing of the front element from the two at the rear.
In earlier adjustment attempts I noted that when inside of focus, the adjusters for the main assembly seemed to have most affect on the airy disc pattern, and when outside of focus, the front element adjustments seemed to have most affect on the pattern.
As I have progressed, it seems I am getting interference patterns set up from two sets of airy Discs rather than just one.
I am also reconciled to my ccd camera set up not providing a clear enough view of the Discs. Perhaps because too small, but I’m now resorting to making an adjustment and then visually looking through the scope with my 3.6mm Tak eyepiece. Hopefully these are signs I’m getting closer.
Meanwhile I’m going nuts. I can see airy Discs in everything now. I can understand the photographic term ‘circles of confusion’ much better now.
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  #23  
Old 27-01-2018, 11:25 AM
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After all my tweaking, a live star test showed the scope is now apparently working reasonably well. I wasn’t sure how to test it out, but I thought I’d go through some doubles. I can easily resolve gaps between a mag 3 and mag 6 star separated by 2 arc seconds. I have nice small round and coloured stars that correspond to the descriptions in my atlas. It is working the best I have ever seen it.

But in the back of my mind, I’m thinking that when I shine a laser collimator through the scope, the reflections from the elements should all be central. And for me they are not. Not even close.

In my first post I asked if someone with a TOA could do this test and report what they see to me to confirm my supposition. So far, no one has come back to me with that information. And I’m thinking it must be critical to the whole process.

So again, please, can somebody carry out this simple laser test on their good TOA and let me know what they see?

Cheers Brian

Last edited by tempestwizz; 27-01-2018 at 11:30 AM. Reason: Error in sizing
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  #24  
Old 27-01-2018, 03:54 PM
sharpiel
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Brian,

Have you confirmed your laser is accurately concentric and squared?
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  #25  
Old 27-01-2018, 04:50 PM
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Yes. Many times and at great length. It is one of the solid 2” Howie Glatter variety.
As a confidence check, spinning the laser collimator in the focuser does not alter the positions of the reflections.
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  #26  
Old 30-01-2018, 12:20 PM
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Sharpie graciously offered his assistance a couple of nights ago, and we were able to ascertain that the laser reflections within his TOA did not select to the central spot of the focuser either, although they were within less than 1 cm by eye, and closer to the centre than mine were. Sharpie advised that he does not photograph through it, but his scope performs very well visually.

This seems to infer that maybe there is a range within the collimation adjustments that returns acceptable viewing results. Maybe there is the one perfect setting, but around it a region of acceptability .

Armed with this information I decided to have another attempt to align the central reflections better than what I had. Mine consisted of one major reflection about 1.5 cm from centre at 12 o’clock position, and another lesser on about 2 cm out at 10:30.

I again completely removed the lens assembly. Initially I checked the reflections with just the front element removed and I was greeted with an asterism of a three dot pattern. One fainter dot up at an 11 o’clock position and two brighter ones at about 3:30 and 4:30 position but closer to the centre.
As another source of confusion, I noted that when I held the assembly(only the two rear elements) against the mounting plate, and rotated it, the asterism did not rotate with the assembly. As I rotated, the asterism moved around as a whole with a small circular motion, but did not itself rotate.??

I rotated the laser source and racked the focuser in and out, but it had minimal affect on what I observed.

Not to be put off, I removed the rear element and replaced the assembly (with just the central element now). I noted a single returned reflection not far from the centre.
I used the adjusting screws to centre this reflection, and now noted that when I rotated the whole assembly, this central dot remained in place.
I then replaced the rear element, and noted again that I had a three star asterism again, although the two brighter reflections were much closer to the centre now. Rotation the whole assembly produced the same result as before. The asterism did not rotate but moved (now slightly) as a whole around the centre.
In an effort of completeness, I removed the rear element, and rotated it 90 degrees before replacing it. The affect on the observations was again minimal. I rotated it a further 90 degrees and again minimal change (if any).
Convinced that the rotational placement of the rear element has no major affect on things, I replaced the assembly into the OTA and secured it with the mounting screws.
Now I loosely held the front element onto the assembly, and noted that I now had my major reflection very close to the centre of the focuser. Rotating the front element had no affect on location of the reflection.
I fixed the front element back on with the mounting screws, and then went through the fine alignment with the artificial star.

The settings for the adjusting screws were not far off, and I quickly achieved alignment again. (5 previous days of practice helped too).

With fine adjustment set, the laser major laser reflection is within about 4 mm of the centre. The earlier second and fainter reflection is no longer visible.

Although the sky conditions were not good last night, Star tests showed the scope appears to be working well. I managed to visually split a 2 arcsecond double star despite the unstable conditions.

I’m quietly confident that I now have the scope back to better than I have seen it before. I have demonstrated to myself at least that it is possible to completely strip it down and rebuild it with minimal equipment. Artificial star and Howie Glatter laser collimator.
I’m still to work out how to get iPhone pics small enough to post here.

The words of my father echo in my brain,
“ you’ll never know if you don’t have a go”
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  #27  
Old 30-01-2018, 12:37 PM
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Tinderboxsky (Steve)
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Brian, there is a way to resize images using your IPhone. Simply email the images to yourself. Mail will ask you whether you want to resize the file to save data etc. The "small" option offered is too small and very low resolution. I have used the "medium" option successfully to resize to fit IIS and still have reasonable resolution. The "large" option will work too depending on the number of images and the total file size.
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  #28  
Old 30-01-2018, 12:53 PM
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The Mekon (John Briggs)
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Well done Brian. Taking on a challenge like this takes some courage. And a big raspberry to all the naysayers (they seem to have all disappeared)
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  #29  
Old 30-01-2018, 04:30 PM
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Well done indeed !!!

Don't forget to put some desiccant sachets to dry out any moisture .... I usually put some velcro on the inside of the dew cap and then stick a bag of desiccant to the other half of velcro...
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  #30  
Old 30-01-2018, 04:54 PM
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Atmos (Colin)
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Took me a while to build up the courage to fiddle with the collination screws on my focuser let alone strip down a triplet objective.
I bow before your magnificence

As for iPhone size, I have a 6S and I find the Medium size when emailing is perfect for IIS getting it to ~150kb.
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  #31  
Old 01-02-2018, 02:37 PM
sharpiel
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Any further updates on testing Brian?

I'm very interested to see your step by step dis and re assembly journey in all the pictures you took along the way. Not many of us will have seen the internals of a TOA.
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  #32  
Old 02-02-2018, 11:32 AM
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tempestwizz (Brian)
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Sorry, nothing further to add yet. We’ve been clouded over pretty solid the last few days. Quite cold for Laos. I will try and get my photos into a postable file meanwhile.
Thanks for the words of support..
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  #33  
Old 02-02-2018, 11:16 PM
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tempestwizz (Brian)
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As promised some pictures of the lens elements from the TOA 130 during the collimation exercise.
Basically shows the system exposed with the lens hood removed.
The front element has a ring of plastic tape around its circumference making an air/dust seal between it and the second element.
Can see down the throat of the OTA.
Can see the assembly in a couple of angles, and with the front element removed.
Also looking into the scope with a Howie Glatter laser collimator inserted. Trying only to show what is reflected back onto the collimator face.
One pic has two obvious reflections, one brighter than the other. At that stage, the airy disc patterns looked quite acceptable, and the ‘live ‘ test produced good stars, . I could separate a 2arc second double. I couldn’t see any colour fringing on the edges of the moon.

After removal of the assembly and replacing only the centre element for alignment firstly, and then without changing the alignment positions for the inner elements, replace all the elements and re-tweaked the front element for good airy Discs again, I got the second Howie Glatter picture. The Brighter of the two earlier reflections is now almost spot on the centre. There is still another (in real life much fainter) dot visible.

But in actual viewing, i cannot really notice a difference after my second attempt. Everything seems to be quite OK still.

I’ll stew on it for a few months, but I think I’ll be happy with it.
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  #34  
Old 04-04-2018, 12:56 PM
sharpiel
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How's it performing Brian? Still happy?
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