Ritchey–Chrétien Collimation without Tears

A concise yet hopefully comprehensive description of how to successfully collimate an RC telescope, in the comfort of/on your dining table. Full size images on Astrobin : https://app.astrobin.com/u/Herbert_Hamber Complete 36-page pdf file here : https://drive.google.com/file/d/1dzDI6eC_n3wWqjKN7Gsas-YW3RIguLfX/view?usp=drive_link https://www.facebook.com/groups/618595048870859/permalink/1726172814779738 https://www.facebook.com/groups/231817878809111/permalink/1006119311378960 Collimation done with the $165 OCAL electronic collimator (v. 2.0 and 3.0) from Aliexpress. On two iOptron (GSO) RC8 and RC6 scopes, completely stock out of the box w/o any extra gadgets. With three metric hex drivers and a flashlight the whole procedure can be completed on a kitchen table in less than ten minutes, with dead-accurate results. As explained in the video, the OCAL is best suited for RC telescopes, and NOT for SCT's (due to the front glass corrector plate) or Newtonians (for which a $22 Svbony laser collimator is known to work perfectly well). Equipment used : iOptron RC8, RC6, Celestron C8, HEQ5 and AVX mounts, Risingcam IMX571 cameras, no guiding, no apps, no gadgets, optical polar alignment, manual focus with Bahtinov mask. Images stacked in DSS and minimally edited in Gimp. My recent images featured in USA Today: https://www.usatoday.com/story/news/nation/2024/03/21/telescope-images-capture-galaxies-see-photos/72856126007/ How to collimate a *Schmidt-Cassegrain* telescope in a few minutes with an artificial star : https://www.youtube.com/watch?v=hqRVIDj4aZA How to collimate a *Newtonian* telescope in a few minutes with a $22 laser collimator : https://www.youtube.com/watch?v=8G98RTP6jbY SVbony $22 laser collimator for Newtonians : https://www.amazon.com/gp/product/B00LX34ZH2/ Possibly useful links : iOptron 8-inch Ritchey–Chrétien Telescope : https://www.highpointscientific.com/ioptron-8-photron-rc-telescope-ota-6112 https://agenaastro.com/ioptron-photron-8-ritchey-chretien-astrograph-telescope-steel-ota-6112.html http://www.gs-telescope.com/content.asp?id=149 iOptron Ritchey–Chrétien 6-inch Telescope : https://www.highpointscientific.com/ioptron-6-photron-rc-telescope-ota-6111 https://agenaastro.com/catalog/product/view/id/12621/s/ioptron-photron-6-ritchey-chretien-astrograph-telescope-steel-ota-6111/ http://www.gs-telescope.com/content.asp?id=150 Celestron Schmidt-Cassegrain 8-inch Telescope : https://www.amazon.com/Celestron-NexStar-8-SE-Telescope/dp/B000GUFOC8/ref=asc_df_B000GUFOC8 https://www.highpointscientific.com/celestron-c8-a-sct-aluminum-optical-tube-with-cge-dovetail-91024-xlt https://agenaastro.com/celestron-c8-a-xlt-cge-ota-91024-xlt.html OCAL electronic collimator $168 : https://www.aliexpress.us/item/3256806481941775.html https://www.aliexpress.us/item/3256806174495568.html https://www.aliexpress.us/item/3256807018278684.html http://www.ocalworld.com/en/product-show.html https://agenaastro.com/ocal-electronic-collimator-pro-version-3-0max.html OCAL Software here : http://www.ocalworld.com/en/software-download.html OCAL manuals : http://www.ocalworld.com/en/product-tutorial.html Note that the newer (green) OCAL 3.0 has a serious flaw, the large dark lens on the camera makes it impossible to see the black donut printed on the center of the RC secondary mirror. This is absolutely crucial for precise RC collimation. The older 2.0 version (red camera housing with shiny metal ring around the dark lens holder) does not suffer from this fatal flaw. Excellent Orion GSO RC8 manual : https://www.manualslib.com/download/2047191/Orion-Ritchey-Chretien-8268.html Disclaimer : I am not sponsored by anybody, nor do I receive any free or discounted merchandise. Original size images on Astrobin : https://www.astrobin.com/search/?q=RC8+Hamber #celestron #astrophotography #telescope 0:00 Introduction 1:00 Collimation Methods for Reflectors 1:48 Ritchey-Chretien Collimation 2:24 OCAL Camera Installation 3:30 Collimation via Concentric Circles 5:15 RC8 Star Test and Sample Images 6:11 The Schmidt-Cassegrain Case 7:21 C8 SCT Star Test and Sample Images 7:54 RC6 Electronic Collimation 8:26 RC6 Star Test and Sample Images 8:59 Hale Telescope 200 inch