First Light: BST Explorers 18mm, 12mm and 8mm with 200p Skyliner.

[sockgoblin]

On 14/01/2017 at 21:29, sockgoblin said:

Ive now tried the 12mm with my Heritage 130p and it didnt play nice at all. The central vane and mirror kept appearing in the view and the curvature of the view was very apparent , my 12mm Revelation plossl is much better on the little scope

OK Ive tried to understand what is going on and it appears that I, and not the Eyepieces, am the problem.

Each of the BSTs have a retractable cover that unscrews to form a hood around the glass. On my skyliner 200p each of the EPs worked well with the cover at full extension. On the Heritage 130p full extension of the cap must place my eye in such a position that I can see the secondary mirror and the mirror vane as a black line and blob superimposed on the primary mirror. If I position the lens hood halfway in all is well as my eye is allowed to go to the correct place to see the image.

I can replicate the issue with my Vixen NPL 32mm so I know that is not a problem with the BSTS.

 

[Charic]

Raising the eye-guard may have a slight effect on the position of your eye, in relation to the eye-relief. On my Starguiders all guards are fully extended when in use.
My TV  Delos features a twist-grip locking feature, keeping the eye-guard in the set position, even when re-stowed!

I also came across one BST where the eye-guard mechanism did not appear to rise in the correct manner.  A firmer grip freed the mechanism, probably over-torqued during manufacture, therefore only  allowing  the outer rubber grip to rotate, rather than rise. That same eyepiece has never caused any issue since.