Screwing or not screwing the coma corrector to the newton focuser that's the question - Forums

Topic starter

6 days ago

Hi,

I have searched for this basic question without obvious answer. I have newtonians for astroimaging and they need a coma corrector. Up to now, I had a GPU or MPCC screwed to my focusers because I heard that it was better. BUT I am preparing a new setup and might have to choose the televue paracorr (photo) to get the right focal length after correction with a 250F4 newtonian. This coma corrector doesn’t offer an obvious way to be screwed to a focuser unless I design and ask some dedicated manufacturer to mile it for me. So here comes the question?

Is screwing the only way to achieve a centered and rigid imaging train (in my case, rotator, Electronic tilt adjuster, EFW, camera)?

What is the experience in real life of those of you who are using some self centering focuser adapter to carry their imaging train?

Thank you in advance for sharing your experience,

CS Frédéric

andrea tasselli

Frequent contributor

6 days ago · Edited: 6 days ago

I never attached my CCs to the focusers with anything other than the 3 screws (so press-fit) and I was never the worse for it, you only need to be very very careful when securing the imaging train in order to avoid introducing tilt. I have tilt corrector though.

Tony Gondola

Frequent contributor

6 days ago

Threaded connections can introduce tilt as well so to my mind, the only advantage is that it’s more secure. To counter that I have the back end secured with a simple lanyard as a fail-safe for forgetfulness.

TiffsAndAstro

6 days ago

I never realised there was a way to screw the entire image train together for newts. Main reason I've avoided them

Wil be interesting to read responses. No way would I use screws or a compression ring.

Joey Conenna

6 days ago

I have only ever used slip in coma correctors secured by a compression ring. I currently use a Feathertouch crayford with one screw pressing the compression ring tightly onto the Paracorr II coma corrector. I could use two screws for more security, but I forgo three screws as the coma corrector might not register with the drawtube consistently (it could float in the middle). I routinely rotate the coma corrector / imaging train for framing and tighten the screw to secure everything and have not had issues with tilt or things not holding. I would prefer a threaded connection, but I am living just fine without one.

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Frédéric Ruciak

Topic starter

5 days ago

Hi, thank you for your feedback, I can go for “slip and tight” without fear. For those wondering how to screw here is the link to an adapter that works with TS GPU to screw on a 54mm female thread of a focuser. It works with MPCC too. https://www.teleskop-express.de/en/adaptors-10/adapter-camera-bayonet-132/ts-optics-adapter-from-m48-2-filter-thread-to-m54x0-75-thread-4041

CS Frédéric