Thursday, October 07, 2010

little better

Tried to collimate the 76mm Firstscope reflector.

Removed the primary mirror. Made a 76mm diameter circle. Punched a hole in the centre. Marked the mirror. Reassembled. Someone suggested that if the back screw holes were slotted, you could tilt the primary.

The mirror is fairly thick glass. About 7 or 8 mm.

The secondary mirror appears to have been glued to the holder slightly rotated. Does this affect performance? There are 3 long screws that go through the vane into the mirror mount. Between the vane and mount is a small rubber grommet. It appears that the 3 screws can be loosened and tigthened to change the tilt.

The secondary vane screws (with a locking nut) into a tall nut (both 7mm) which holds one side of the focuser. Remounting is a challenge. It's easier to lock the secondary vane to the big nut, then tighten down the big nut with the (Phillips) screw atop the focuser.

Never could see the entire primary through the pinhole collimator. Is this critical?

With the dot on the mirror, I believe I was able to finally get the optical path collimated. And I believe the star and planet images have improved. Particularly when objects are kept in the centre of the field. My left eye had something in it that wouldn't clear; I just can't see (perceive) as well with my right eye.

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