Lunt 50mm + ZWO focusing problem

[baggywrinkle]

I have been trying to achieve focus with my ZWO120MM mono camera on a Lunt 50mm Solar scope with a helical focuser. Just not enough focus travel. I tried a 2x Barlow and that did not work either. Any advice please? 

[Owmuchonomy]

Yep, been there done that. My astro diary of 3rd March reads "...it is necessary to pull the blocking filter out from the focuser by about 11mm".  I don't have my Lunt 50 now but I remember using the photo adapter ring that came with it as a spacer.

[Moonshane]

the general way to focus with a helical is to set the helical focuser at about half travel point, then pull the accessory out (assuming it's safe to do so) to a point where you are in focus and then use the helical as a fine adjuster. 

[baggywrinkle]

Just had an email from Simon Bennett at the Widescreen Centre and he advises to  'remove the 1.25” eyepiece holder, with the T-thread on top. If you unscrew this holder from the blocking diagonal, you expose another T-thread

If you then unscrew the 1.25” nosepiece from the ZWO camera, you can then put the camera body directly onto the diagonal, saving about 40mm of backfocus. You can then rotate the blocking diagonal in the telescope to orient the image as required.

the 1.25” eyepiece holder, with the T-thread on top. If you unscrew this holder from the blocking diagonal, you expose another T-thread.'

 

Will give that a try.

 

If you then unscrew the 1.25” nosepiece from the ZWO camera, you can then put the camera body directly onto the diagonal, saving about 40mm of backfocus. You can then rotate the blocking diagonal in the telescope to orient the image as required.

[Pete Presland]

I posted quite a few photos regarding this subject last August,  a quick lunt 50 ser ch should find them.I also did the screwing direct into the diagonal in the end, but switched to a DMK21AU618 after getting fed up with the newton rings.

[knobby]

2 hours ago, baggywrinkle said:

Just had an email from Simon Bennett at the Widescreen Centre and he advises to  'remove the 1.25” eyepiece holder, with the T-thread on top. If you unscrew this holder from the blocking diagonal, you expose another T-thread

If you then unscrew the 1.25” nosepiece from the ZWO camera, you can then put the camera body directly onto the diagonal, saving about 40mm of backfocus. You can then rotate the blocking diagonal in the telescope to orient the image as required.

the 1.25” eyepiece holder, with the T-thread on top. If you unscrew this holder from the blocking diagonal, you expose another T-thread.'

 

Will give that a try.

 

If you then unscrew the 1.25” nosepiece from the ZWO camera, you can then put the camera body directly onto the diagonal, saving about 40mm of backfocus. You can then rotate the blocking diagonal in the telescope to orient the image as required.

This works fine, thays Howw

[knobby]

Sorry can't edit on phone for some reason,  screw direct to diagonal and pull diagonal out of focuser about 10 mm.

[baggywrinkle]

I can now use the ZWO.....happy bunny!