Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Lens cell factory defect?

  • Please log in to reply
25 replies to this topic

#26 Rutilus

Rutilus

    Vanguard

  • *****
  • Posts: 2,459
  • Joined: 17 Dec 2010

Posted 14 January 2020 - 02:40 AM

So are you suggesting to try and adjust the pressure of the retaining ring?

Adjusting the pressure on the retaining ring will make no difference.

If you can not see a very clear strong Newton ring pattern in the lens, then your lens is fitted

with a spacer ring, and adjusting the pressure on the retaining ring will make no difference to the S.A.

 

With my scope I replaced the spacer ring with thinner spacers, the star test shows a better ring pattern each

side of focus, but it still has slight under-correction, but better than when I first received the scope.

There is only so much that you can do. While being an achromat, my scope still shows plenty of Planetary detail.

Here is a drawing I made of Mars, each drawing was made 24 hours apart but in the  same seeing conditions,

one was made with my 120mm Achromat and the other with my Takahashi TSA-102.  

Attached Thumbnails

  • 120-cn.jpg

  • Bomber Bob and balticsensor like this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics