2" filter use on Skywatcher Newtonians

[DevonSkies]

My Skywatcher 250PX Dobsonian,  like many SW Newtonians, comes with 1.25" and 2" eyepiece adapters. Unfortunately these aren't threaded, which leads to a problem if you want to use 2" filters with a 1.25" eyepiece. I have found a solution to this, which might be of use to others who have a SW Newt with a 2" focuser.

The solution is to replace the 2" eyepiece adapter with a 2" extension tube of the correct length, combined with a low-profile 2"-to-1.25" adapter. I looked at a few options and settled on the Revelation 35mm self-centering 2" extension tube:

http://www.telescopehouse.com/accessories/eyepiece-adaptors-and-extension-tubes/revelation-self-center-35mm-extension-tube-2.html

This is the same length as the original 2" eyepiece adapter, and it is threaded to accept 2" filters. It fits straight into the focuser and replaces the original 2" EP holder. I then added the Revelation 2"-1.25" self-centering adapter:

http://www.telescopehouse.com/accessories/eyepiece-adaptors-and-extension-tubes/revelation-self-center-adapter-1-25.html

The two adapters combine to make an extension tube with exactly the same length as the original 1.25" EP holder. Both adapters are threaded, so a 2" filter can be fitted to either part. I chose the self centering adapters because they have a low profile and therefore don't alter the amount of focus travel available with the SW focuser.

I hope this will be of use to someone else!

Note: apparently some earlier SW Newtonians don't have a standard 2" drawtube fitting, so this method won't work. So it's worth checking your focuser has a standard 2" fitting before spending any money!

Ed

[rockystar]

I've got these also (Altair Astro branded), with the same thought in mind - along with the fact that they are much sturdier than the supplied extensions.

I was also thinking of upgrading my eyepieces to the Morpheus range and doing away with the adaptor - word of caution though (for anyone thinking of doing the same), you will need the 50mm version, as there wasn't enough outward focus when using in 2" mode.