The left is “after”, and the right is “before”.
Here is the wise solution of extending the back-focus.
It is the restorable customize of the focuser setting.
The improved version of the EMS-UL is just ready to produce.
You may remember the announcement of the new version of EMS-UL posted on My 18th. With the stock of the new joint rings being ready, I am finishing the number-1 pair of the new EMS-UL SET for the US.
The new EMS-UL of the standard(minimum) spacing has evolved in terms of the following.
1.light-path-L1 was shortened by 2mm.
2.The rigidity of the joint increased by the simpler structure.
From 3-pieces to 2-pieces of the parts included.
3.Aperture rim is added at the end of the joint ring.
(It will improve the contrast.)
Now, I am announcinG the new definition of the light-path of the EMS.
The new definition of the light path consists of the two parts.
One is the L1,the fundamental lighg path, from the rim of the barrel to the rim of the filter flange. And the othre is L2, that is the height of the eye-piece adapter, in this case, 2-inch sleeve.
And the total light path is LL=L1+L2.
The comparison of the light path between the old and the new EMS-UL is the following.
OLD EMS-UL— L1+L2=92+58=150mm=LL
NEW EMS-UL— L1+L2=90+58=148mm=LL;
LL= total light path.
To minimize the L1 has the significant meaning in benifiting the margin of the back-focus of the scope. On the other hand just reducing the L2,the height of the adapter, is like a trick that must be canceled at the actual usage.
I will also show you the precise light-path of the EMS-UM in passing.
I must apologize to you for the wrong desplay of 120mm for a long time.
The reason was just simple. At the release of the EMS-UM, the original 31.7mm-adapter was 42mm in height, but later changed to 44mm by the report of users that so many eye-pieces touched the protective filter on the tip of the barrel.