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Old 31-07-2023, 01:14 PM
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mldee (Mike)
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mldee is offline
 
Join Date: Aug 2008
Location: Near Warwick, Qld, Australia
Posts: 656
Pimp my RC8 and collimate with OCAL

After many moons of my RC8 and other scopes slumbering in my obs, which has a decidedly heavy 10" truss f4 Newt astrograph firmly attached to the CEM60, never to be removed, I decided to resurrect the RC8 on a second external pier with a recently completed small roll off shed for pier cover. That's now all done.

So, time to get the RC8 into working order, and after reading up on all the latest forum news, it's been full steam ahead. First item was to purchase the 90mm to 42mm adaptor plate to allow OCAL direct connection to the rear mirror threads. Done.

Second was the GSO tilt adaptor plate to rectify any tilt in the imaging train. Done.

Third was to procure a decoupling adaptor plate to detach the imaging train from the mirror assembly. In process. Basically just The Big Pimp. Guy on the FB RC8 forum design:https://tinyl.io/93aM

The collimation steps started with no imaging train, Laser then OCAL connected direct to the mirror then collimate. Pretty straight forward after watching all the YouTube videos on the subject.

Check and adjust imaging train for tilt using laser + flat mirror technique, then connect imaging train to OTA and adjust secondary mirror for good laser return spot.

Connect OCAL to imaging train camera position, preferably threaded. Check and fine-adjust mirror and tilt as necessary until optical alignment seems correct. See pic below. Repeat laser and OCAL steps until both are good.

Place the RC8 on a mount and confirm with defocused star test. Fine adjust secondary mirror screws to achieve a perfect donut shape. It should only require minor movement of the screws. I did it in the freezing cold in about 2 minutes.

Finally, replace the stock GSO focuser with the TS optics rack and pinion model, due to slippage and subsequent unreliable autofocus in NINA. Done and the TS version highly recommended and easy to install the ZWO EAF bracket.

Hopefully all this was not just a lipstick/pig effort

Now I get to do low-elevation northern imaging with Bortle 2 exposure durations

Pics show RC8 Pimp/collimation setup and OCAL results.
Attached Thumbnails
Click for full-size image (DD RC8 final.jpg)
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Click for full-size image (RC8 Coll full OCALsetup.jpg)
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Click for full-size image (RC8 GSO OCAL 1.jpg)
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Click for full-size image (RC8 OCAL result 1.jpg)
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Click for full-size image (RC8 OCAL settings.jpg)
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Click for full-size image (RC8 tilt adaptor plate 3d.jpg)
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Click for full-size image (RC8  tilt adaptor plate.jpg)
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Click for full-size image (RC8 TS camera 1.jpg)
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