{"id":717,"date":"2015-02-09T16:04:19","date_gmt":"2015-02-09T15:04:19","guid":{"rendered":"https:\/\/www.primalucelab.com\/astronomy\/blog\/?p=717"},"modified":"2021-08-31T14:44:47","modified_gmt":"2021-08-31T12:44:47","slug":"flessioni-in-autoguida-autoguide-flexures","status":"publish","type":"post","link":"https:\/\/www.primalucelab.com\/blog\/flessioni-in-autoguida-autoguide-flexures\/","title":{"rendered":"Autoguide flexures"},"content":{"rendered":"

Autoguide flexures: the use of an autoguider to improve the tracking accuracy of the telescope mount not only requires a sensitive camera and a good guide telescope (or an off-axis guider) but also a properly machined\u00a0mechanical system that is able\u00a0of supporting it without problems or flexures.<\/p>\n

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I decided to write an article about it when, last week, I received a call for help by an amateur astronomer who could not guide: despite the guide graph that he observed in PHD Guiding software was good, without\u00a0obvious peaks or tracking errors, the images were “moved” and the stars elongated. I do not have with me his pictures but here you have\u00a0an example of how the\u00a0image may appear.<\/p>\n \n\n

\"Autoguide
Autoguide flexures: the use of unsuitable mechanical supports generates flexures and then ruin the images.<\/figcaption><\/figure>\n\n \n\nAfter checking with him that the telescope was perfectly aligned and working, I made hime\u00a0describe to me the guiding system and ….. surprise! He was using\u00a0a guide telescope in parallel to the main one (an apochromatic refractor) with guide rings similar to these that\u00a0have:\n\n1) Plastic screws to lock the guide\u00a0scope\n2)\u00a0Single screw to lock them on plates or support rings\n\n \n\n
\"Autoguide
Autoguide flexures: cheap guide rings.<\/figcaption><\/figure>\n\n \n\nDespite this kind of support\u00a0have the great advantage of a very cheap cost, it is undeniable that it has\u00a0some construction problems that, potentially, can generate autoguide flexures and then thwart the efforts we make in astrophotography . In fact, no high sensitivity autoguide or high precision mount\u00a0can\u00a0work perfectly if the mechanical system is not rigid. What happens is very simple: when we use rings similar to these, during extended exposures in deep-sky exposures, the parallel guiding telescope moves imperceptibly (but it moves ….) relative to the main one. The guide camera\u00a0continues to adjust the position of the mount\u00a0based on the star pointed by the guide telescope but it moves with respect to the main one: the result is a noticeable “shift”.\n\nThat’s why\u00a0guide rings, also if\u00a0simple instruments, must be carefully machined to avoid autoguide flexures. Let’s see\u00a0for example in our PLUS guide rings and see the differences from the previous ones. They’re more espensive (although not so much) but they have large aluminum screws (with Nylon head to avoid scratching the guide telescope) and they have\u00a0at the base 3 threaded holes to a more stable allow installation. Moreover the base (where there are 3 holes) is flat to allow an even more secure fastening.\n\n \n\n
\"Autoguide
Autoguide flexures: our PLUS guide rings avoid flexures.<\/figcaption><\/figure>\n\n \n\nOur PLUS guide rings can be installed on support rings or plates of all brands (thanks to the presence of a centrale threaded hole) but they connect to the best to all the elements of the PLUS system using, for each ring, 2 M6 screws. This way you will be sure that the telescope will be installed\u00a0in parallel with high rigidity and that you will not have autoguide flexure problems that ruin your pictures.\n\n \n\n
\"Autoguide
Autoguide flexures: PLUS guide rings allow to support the guide telescope preventing dangerous flexures.<\/figcaption><\/figure>
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