Hi all,
First, many thanks to acropolite for the bundle of optical fiber,
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Resulted that the EP I had to make a reticle for couldn't be wired like the first one I made. The field stop in this 25mm Super Plossl is positioned at the focus of the EP. All I had to do was measure the widest diameter of the stop's span and cut two optic fiber lengths to this length. I then drilled out undercut ledges to sit the fibers across the span. The undercuts help give some mechanical retention to the epoxy glue used to fix the fibers, lest the hold of the glue fail, the undercuts will hold.
The first picture shows the EP with its barrel removed for access to the field stop. The tiny undercut holes were done using a 'Dremel' type tool. The second pic show the barrel restored and how well protected the delicate fibers are.
Mental.