24th October: More PST modding PT2: GPC.

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A little online homework later: The plastic ring is actually a push fit inside the small end of what is intended as a 2" nosepiece. [Which I earlier called an adapter.] The GPC is then pressed into the plastic ring and trapped in place by the next component. Usually a binoviewer. The flange on the GPC is very thin and sharp so threading the GPC into the ring might bring tears or blood. Pressing it into place in the plastic ring should be done square-on and gently. The thin flange is obviously intended not to use up any more focal length [nor thread length] than absolutely necessary.

The GPC lens housing has lots of useful text in English wrapped around it. Using the GPC as a Barlow will cause colour error. The device is designed to compensate for Glass Path Length of the Baader MkV/Maxbright binoviewer. The knurled ring on the nosepiece is intended as an adjustable stop for the T2 male thread. Care should be taken not to allow the GPC to fall out of its plastic ring prior to trapping it safely by threading on the binoviewer or following component. The convex side of the lens should face the telescope.

The inside of the nosepiece is threaded for a 2" filter. So there may be a way to adapt something to this thread. To support the GPC safely in a PST H-alpha telescope conversion.  An empty 2" filter ring?


The AOK front etalon adapter is also threaded for 2" M48x 0.75mm filters. The GPC flange fits inside the 2" thread in the nosepiece though rather loosely. So concentricity must be carefully attended to. A couple of male, all threaded, 2" filter rings could trap the GPC between them in the front, AOK etalon adapter quite nicely.

 https://www.teleskop-express.de/shop/product_info.php/info/p4516_TS-Optics-Adapter---continuous-male-M48-thread--as-with-2--filters-.html

No need for any extra expense or modification. The Baader 2" binoviewer nosepiece is intended to hold the GPC firmly in a plastic ring with the correct orientation. Convex lens pointing towards the telescope. Read the instructions printed in tiny text around the GPC lens barrel.

Once the large, knurled ring is removed from the nosepiece the whole assembly can be slid straight into my 2" x 60mm WO extender. Which screws onto my home made backplate. The AOK front etalon adapter pushes the Baader nosepiece forwards to a suitable position inside the WO extender. See images above.

Click on any image for an enlargement.

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