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02-15-2019, 10:27 AM   #1
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Join Date: Aug 2008
Location: Massachusetts
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T Adapter for telescope

I plan to use my ISTds with a 4 in Celestron refractor. I need help to determine the correct adapter. There is a 2 inch adapter on the draw tube that attaches to a 1.25 inch diagonal for use with 1.25 inch eyepieces. The diagonal unscrews and would accept a 1.25 adapter. Also, not sure if someone makes a 2 inch camera adapter that would fit 2 inch opening(not threaded). Is there a benefit for type ?

Thanks for your suggestions.


02-15-2019, 10:48 AM   #2
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Join Date: Feb 2010
Location: Maryland
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Yes it is best to get a 2” K-mount adapter since it will be more versatile later if you go to full frame sensor. Here’s one:

Pentax K SLR / DSLR 2" UltraWide True-2 Prime Focus Adapter - Telescope Camera Adapters |

For prime focus without diagonal you probably will need a 2” extension. Hard to know until you try. See here:

Last edited by Pentax Syntax; 02-15-2019 at 10:54 AM.
02-16-2019, 12:47 PM   #3
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Join Date: Sep 2014
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Glad to see some astrophotographers here, Pentax Syntax suggestion is spot on Highpointscientific has a great selection and lots of help if you have any questions. From my very basic understanding depending on the tube length image may not fill the sensor.
Ordering a Skyguider from HPS this spring, along with my current camera and lens set up try and improve my astro shots. Not sure how deep space I can get with a 200-400mm lens and unmodded DSLR but soon to find out, but a start. Just watched Deep Sky Imaging by Glenn Newell on Youtube awesome stuff!

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