Jeff, can they be used with the Antlia 3 nm mounted rings or are they only for unmounted glass?
As Jeff explained, the Antlia filter must be disassembled by removing the lock ring.
The 2" ScopeStuff filter cell appears to be the same as the Blue Fireball filter cell sold by Agena, found here: https://agenaastro.c...-cell-s-2f.html
And it can be used with the Antlia 2" 3.5nm filter... with the following adjustments.
The Antlia filter does fit nicely in this cell. But I had to find a different lock ring for the cell, because the stock lock ring is very thick. By the time a 2mm thick filter is installed and the Blue Fireball lock ring is added, there are no front filter threads left to use. So I used a thinner lock ring from a Neewer filter which worked perfectly and left about 2.5mm of front threads.
The Antlia filter glass does fit the Blue Fireball cell nicely. However, It did not fit a Neewer cell that I tried first. Conversely, a 2" Optolong filter fit the Neewer filter cell but not the Blue Fireball. There is a few millimeters difference between the diameters of these two glass filters.
jay.i, in answer to your question about why front threads might be needed, I use 2" filters as part of my Nikon camera lens adapter, seen in the photos below. The Blue Fireball cell is very stout for a strong connection, but it is thick with a light path of about 7mm. You can see it in the photos with the smooth silver line on the rim. This adapter system uses a RAF C-mount to M48 adapter, the filter cell, an M48 to M42 adapter and the M42 to Nikon adapter. I use it with each of my four prime lenses, including an f:2.8 300mm, with excellent results.
2" Antlia 3.5nm filter in a Blue Fireball filter cell
Filter cell installed between C-mount NVD and Nikon adapter
With 50mm camera lens attached
Edited by GeezerGazer, 06 January 2021 - 11:12 PM.