SW coma corrector in-travel mod

[Rustysplit]

Following on from Simons's post re the Baader mk111 and focuser travel, I thought it might be useful to show what I did to my coma corrector to gain the all important in-travel.

I really like the standard SW CC as it acts as a .9x reducer as well, thus giving a slightly wider fov for any given eyepiece. It also speeds the scope up, thus making my native F5 work at F4.5. TBH, not too important for visual, other than it may begin to show up weaknesses in mid range ep's? The other benefit is it's cost compared to a Paracorr, less than a 1/3rd, and the fact the Paracorr actually narrows your fov by about .15x iirc.

Whilst my 27mm Pan came to focus , my Radians needed just a bit more in travel. The pics show what I did. There used to be a wider flange around the base of the thread on the actual CC, which butted up against the shoulder of the focuser. I stuck it in a lathe and turned this down to the same 2" size as the the rest, and also turned a section of the visual ep adapter shoulder. You have to be careful not to machine this bit too much, or the end will come off   This has given me another 10mm of in-travel and means that the CC can stay in the focuser with no need to swap spacers about, other than slipping in a low profile 1.25" adapter for the Radians.

Works like a charm, and it will still accept a T-ring for astrophotography. Hope this may be of some use.

[SimonfromSussex]

Nifty adaption Alan, where does this sit in the focuser?

At point A or point B?

Also can I ask where did you get the eyepiece holder?

I wonder if this would work with mine, it's just whether I can get focus (assuming the adapter sits at point A)?

[Rustysplit]

Sits in at point A mate.

 The ep adapter comes with the SW CC as standard. With the baader, you would get a similar thing if you had bought the visual kit I think. From the top of the ep adapter to point A is 46mm.

[SimonfromSussex]

Cheers matey, sadly the one that comes with the baader only has a 1.25" hole, I assume your's takes 2" & 1.25"?

If the ethos will focus with the tip of the eyepiece at point A (which I can test without an adapter) then if I can find an ep adapter like you have it might work.

I have a horrible feeling the ethos needs to be deeper in the focuser though  .