Collimation tools

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MariusD69 Romania
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Collimation tools

#1

Post by MariusD69 »


Hello!
I bought last year a TS RC8 (I'm the third owner), but I didn't like how the stars looked like. I collimated it with Cheshire and laser, then checking on image with this method : http://www.deepskyinstruments.com/truer ... 1.0.pdfand . Now, the stars look better but not perfect. I would need a better collimation tool (and money for it). Options: Howie Glatter laser collimator with holographic attachment or a Takahashi collimation scope. I would choose the Tak, even though I need an adapter (M90x1F to M36.4x1F(M48x0.75M)) that can be found only in Russia (or Belarus) for $ 40. This is probably the best method using Tak scope: https://www.dropbox.com/sh/1349fp34gqpb ... 1dL4a?dl=0 Due to the situation with the virus and the state of emergency, I cannot order items from outside EU because I can't travel to another city where the customs is. Maybe TS could make it as custom adapter (at a price 3 times higher). Still, I don't know if the distance between primary and secondary is correct( this is critical for RC). That's why I ordered a Ronchi eyepiece.
Finally, while looking at the collimators I saw an interesting one: an adapter with "peep-hole", crosshair and LED. Basically it's a self-lighting Cheshire : https://www.teleskop-express.de/shop/produ...typen.html
I thought: DIY!
The first version is similar to the commercial one. I made it with a 2" barrel. The crosshair is glued on a plastic disk. The power supply is from three AG3 batteries, placed on the side, because they disturb the eyes if they are near the viewing hole. This should be just above (not at the bottom of a 2 "adapter) and large enough (I made it 3.5mm) to have a wider image inside the RC. If it is made for newton it can be smaller . I made a second version using a 40mm T2 extension, but it looks better with 2" barrel. When you look through the hole you see a dark dot ( the viewing hole) which must be placed in center of secondary ring. Instead of crosshair you can use a simple white paper with a hole in the center (it's very important to be exact in the center of barrel). Rotate it to check this.
Version 2.0. Adding a scope (with focus system) and adapting it to the LED collimator. It's basically a LED Tak (the Tak collimator has a Cheshire in front of the objective). I had to make another LED collimator: a 50mm 2" extension with a 1.25" adapter. The chosshair is on the bottom of the adapter (where the M48 thread is), the red LED illuminator is inside the extension and CR2032 battery power outside of it. I made the scope with a Scopetronix 40mm projection eyepiece- as objective (T2 output with sliding barrel), Baader T2- 1.25 "adapter with focus, Super 25mm eyepiece. This can be focused on the secondary mirror's ring, or on the spider (it depends on what I want to see). From my tests, it's better to keep a distance between the "peep-hole" and objective lens (I have about 3cm). Image: Scope v1.0
Version 3.0. Adapting a USB camera( 1.25" body) with 8mm lens to the scope (afocal system). It is useful especially when adjusting secondary screws- you can't watch and adjust at the same time, only if you have orangutan arms.
I made another scope: 50mm CCTV lens with C-mount output, adapted in front and back to T2, an eyepiece from a binocular placed inside of C-mount/ 1.25". With an T2 extension (60mm +17mm+40mm T2/1.25"adapter) I connected the camera to the T2 thread from objective.
Why didn't I use directly a camera with lens placed directly to the "peep-hole"? Because I need to focus at different points (secondary mirror or spider) and it's very hard to collimate camera and lens (the sensor may be not placed in the center of C-mount, the optical axis of this small cheap lens usually is not the same with mechanical axis of mount). I tried to do this collimation with a Philips SPC900 webcam and after 1000 white hairs I quit. It is far much easier to collimate a scope and to retrieve the image with afocal system.
In order to get rid of adapters with tighten screws (we all know the induced problems- push and tilt), I made some modification:
-I changed the 2" adapter of focuser (I replaced before the original monorail Crayford with a 2.5" R&P focuser) with this: https://www.teleskop-express.de/shop/pr ... nd-2-.html From its M54f thread I connected M54m/M48m adapter, then 2" barrel/M48m (the LED collimator), M48/T2; T2/M42; M42 macro ring ( the 50mm CCTV lens is fixed inside it), etc.
Ideally, the system should be used before focuser (with that M90x1/M48 adapter), the same way like Tak scope from the link above. Or, before using the system, the focuser must be align with primary mirror like the first step here: http://www.hnsky.com/RC_collimation.htm
* I will not say that this collimation system is better than Tak, but it could be the same if it's executed carefully with proper items. I just used what I found in the box with adapters and it can be improved by those with more resources.
** Please excuse my grammar mistakes (my English is from "Teach Yourself English" books). The only practice is from this forum.
Attachments
Scope v1.0.jpg
LED collimator v1.0.jpg
Camera+Collimator+scope 2.0.jpg
Final LED collimator.jpg
Test LED Tak.jpg
Marius
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helicon United States of America
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Re: Collimation tools

#2

Post by helicon »


Thanks for sharing your experience.
-Michael
Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope
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Re: Collimation tools

#3

Post by JayTee »


Ingenious Marius. Very nice work.

Now I'll see if I can't duplicate this and have one for myself, for my RC.

Cheers,
JT
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Re: Collimation tools

#4

Post by Lady Fraktor »


Very nice work Marius.
Years ago almost everyone I knew made their own collimation caps and sight tubes, now you rarely find anyone doing this.
A nice exception :)
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
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Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
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