> Michael Hart wrote:
> <<<There is a small threaded hole on the Optec which allows the use of a small
> brass round head machine screw. The screw is sanded or filed to just allow it
> to insert in the slot on the Optec for the 1-1/4" eyepiece screw. Using this,
> the Optec is indexed to the NGF-S. I do not own the Optec SCT adapter.
> >>>

> Mike,
> I don;t seem to have this hole. There is a hole on the front end of the
> Optec for the guide pin of the Optec SCT adapter. (facing the telescope). And
> there are 3 holes with screws in them, to secure the 416 to the Optec. Where
> would this one be located?
>
> Paul
> The Arcturus Observatory
> http://cometman.com
>

Mine has a threaded hole about 45 degrees from the elongated hole
used for the Optec SCT adapter. I had Optec thread it for me- I believe
they now drill and tap all current models. If your doesn't have one,
you could remove the camera specific adapter via the three set screws
you mentioned and drill the rim for an indexing pin. The indexing pin
is fabricated from a small brass machine screw with the head pointing
away from the CCD camera.

Purchase a long 4-40 brass round head machine screw and a matching
tap and drill. Before you cut off the screw, chuck it into a drill and sand
the side down for a moderately tight fit in the slot on the NGF-S for the
1-1/4" thumbscrew. If it is a bit loose, this isn't critical, as you can
always apply clockwise or counter-clockwise pressure to duplicate
the position. Cut the brass machine screw to about 1 mm long which
is just short of the thickness of the flange. Finally, drill the aluminum
flange quite near the center- err towards the outside rim. Don't try to
run the tap all the way in without frequent tap reversal or the threads
will be rough and the tap may seize.




--
Michael Hart
Husen Observatory

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