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Newtonian Secondary Holders |
Cassegrain Secondary Holder (see below) |
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Newtonian Secondary Holders |
Cassegrain Secondary Holder (see below) |
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 centered 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 aluminum bezel with polyester batting. Available in 19 sizes, ranging from 1.3" to 7.0". Use the link below for dimensions, exact weight and sizing.
This has a #10 mounting stud and a 3/16" to 3/8" bushing to fit 3/8" spiders. The 25mm holder attaches the secondary mirror with double sided tape. The smaller diameter mounting stud reduces the weight by 30%. This utilizes set screws for adjustment and the hex key is supplied.
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.
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.
These have a 3/8" mounting stud and have thumbscrews for easy, no tools collimation. Shown at center in the above photo.
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.
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| 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.
Built in offset, add $18.00 on holders up to 4.5"(please specify amount of offset).
Offset is included in the price of 5" and larger holders (please specify amount of offset).
Dimensions and sizing of secondary holders
Installation and Operation Instructions (pdf)
| Size | ShipWeight | Price | Size | ShipWeight | Price | |
|---|---|---|---|---|---|---|
| 1.0 (25mm) | 1 | $32.00 | ||||
| 1.3 | 1 | $32.00 | 3.0 | 3 | $47.00 | |
| 1.36 | 1 | $34.00 | 3.1 | 3 | $47.00 | |
| 1.52 | 1 | $34.00 | 3.5 | 3 | $51.00 | |
| 1.75 | 1 | $35.00 | 4.0 | 4 | $57.00 | |
| 1.83 | 1 | $35.00 | 4.25 | 5 | $62.00 | |
| 2.0 | 1 | $36.00 | 4.5 | 6 | $67.00 | |
| 2.14 | 1 | $38.00 | 4.75 (120mm) | 6 | $79.00 | |
| 2.25 | 2 | $40.00 | 5.0 | 7 | $110.00** | |
| 2.36 (60mm) | 2 | $42.00 | 5.5 | 7 | $115.00** | |
| 2.5 | 2 | $42.00 | 6.0 | 7 | $125.00** | |
| 2.6 | 2 | $44.00 | 6.25 | 8 | $130.00** | |
| 2.75 (70mm) | 2 | $46.00 | 6.5 | 8 | $135.00** |
**Deduct $18 if not offset
AstroSystems is the largest supplier of Cassegrain secondary holders to the astronomical community. There are no tools needed to adjust holders of 2.6" or larger, they come standard with thumbscrews. All sizes feature our innovative four screw/two-axis adjustment that greatly simplifies collimation. With a four screw adjustment, each screw is centered between the spider vanes, making collimation adjustments a snap. Two nuts with nylon washers position the holder laterally. The secondary mirror is held securely yet safely against the front lip of the aluminum bezel with rigid foam and polyester batting. Available in custom sizes from 3" to 9.0".
| Size | ShipWeight | Price | Size | ShipWeight | Price | |
|---|---|---|---|---|---|---|
| 3.0-3.5 | 3 | $68.00 | 5.6-6.0 | 8 | $125.00 | |
| 3.6-4.0 | 3 | $78.00 | 6.1-7.0 | 9 | $145.00 | |
| 4.1-4.5 | 5 | $88.00 | 7.1-8.0 | 10 | $165.00 | |
| 4.6-5.0 | 7 | $98.00 | 8.1-9.0 | 11 | $185.00 | |
| 5.1-5.5 | 8 | $111.00 |
To Order: Size ranges listed above are for pricing only, holders are made specifically for one mirror diameter. State mirror diameter, thickness and bevel width.