AstroSystems is the largest supplier of secondary holders and spiders to the astronomical community. There are no tools needed to adjust holders of 2.6″ or larger in minor axis size; they come standard with thumbscrews. Holders from 2.1″ and smaller are supplied with a hex key that gives positive seating in the hex screw even in the dark. All sizes feature our innovative four screw/two-axis adjustment that greatly simplifies collimation. With a four screw adjustment, each screw is centred between the spider vanes, making collimation adjustments a snap. Two nuts with nylon washers position the holder laterally and also allow easy adjustment of the rotation. The secondary mirror is held securely yet safely against the front lip of the aluminium bezel with polyester batting. Available in 21 sizes, ranging from 1.3″ to 6.5″. Use the link below for dimensions, exact weight and sizing.
1.3″ to 1.5″
These have a #10 mounting stud and a 3/16″ to 3/8″ bushing to fit 3/8″ spiders. The smaller diameter mounting stud reduces the weight by 30%. They utilize set screws for adjustment and the hex key is supplied.
1.8″ to 2.75″
These have a 1/4″ mounting stud and a 1/4″ to 3/8″ bushing to fit both 1/4″ and 3/8″ spiders. The smaller diameter mounting stud reduces the weight by 30%. The 1.8″ to 2.1″ utilize set screws for adjustment and the proper size hex key is supplied. The 2.5 to 2.75″ have thumbscrews for easy, no tools collimation.
3.0″ to 3.5″
These have a 3/8″ mounting stud and have thumbscrews for easy, no tools collimation. Shown at centre in the above photo.
4.0″ to 4.5″
These larger holders have a proportionately thicker shell for proper support of thicker, heavier secondaries and a 3/8″ mounting stud. They utilize 1″ long thumbscrews for easy, no tools collimation. Shown at right in the above photo.
5″ Holder showing foam mirror support
5″ Holder, 3/8″ adjustment plate, 1/2″ stud and 0.040″ shroud
The larger holders have a proportionately thicker shell for proper support of thicker, heavier secondaries, a thicker (3/8″) adjustment plate and a 1/2″ mounting stud. They utilize 1″ long thumbscrews for easy, no tools collimation. These are also supplied with a foam insert to support heavier secondaries accurately within the holder, necessary for accurate collimation in short f/ratio telescopes .
Please state actual minor axis, Major axis and thickness of the secondary mirror when ordering 2.6″ and larger holders.
If a built in offset is REQUIRED select With Offset (please specify amount of offset at checkout).
If a built in offset is NOT REQUIRED select With Offset.
