On-axis imagining of obstructions mystery

There is something I've been trying to figure out but not sure
what caused it.

Set up an SCT with eyepiece on and aim at bright object like
moon or daytime targets. Stay 1 feet away from the eyepiece
and look at it. You can see the secondary obstruction of the SCT
in the eyepiece and as you get closer ot the eyepiece. The secondary
obstruction would get lighter and at the proper eye relief
distance of the eyepiece, you can still notice a very faded image
of the secondary obstruction causing contrast lost in the center
of the image. Now the mystery is what causes it? Equipment
tested is an 8" Celestron SCT done many times few years ago
and still at a lost to explain it.

Parallel light rays enter the objective at different angles and the
rays converge to a point at the focal plane and the eyepiece.
So theoretically you are not supposed to see or notice
the secondary obstructions when viewing thru the eyepice,
yet you can in a very faded sense. Anyone got any theory why?
Thanks.

Teni