GoldFocus Plus - Cassegrain Ordering
*** Important Notice ***
Use this ordering page only for ordering a
GoldFocus Plus Collimation System for Cassegrains (SCTs, RCs)
which supports focus and collimation for Cassegrain telescopes,
including Schmidt Cassegrains and Ritchey-Chrétiens.
This model of GoldFocus Mask has a hole for access to the secondary mirror
adjustment screws with the mask in-place and the GoldFocus Analysis Software
analyzing real-time collimation and focus.
If you want to order a
GoldFocus High-Precision Focusing System or GoldFocus Plus
Collimation for a different telescope, then click on one of the following:
GoldFocus High-Precision Focusing System
GoldFocus Plus Collimation for Newtonians
GoldFocus Plus Collimation for Refractors
If you already know which GoldFocus Mask size you need to order, click
Select Mask
to immediately go to the GoldFocus Mask size selections. Otherwise follow the steps below
and scroll all the way to the bottom of the page.
Determining the GoldFocus Mask Size
The GoldFocus focusing system for digital imaging is a combination of a specially designed GoldFocus Mask and the GoldFocus Analysis Software. An image of the GoldFocus Mask is shown at the right.
The GoldFocus Plus Collimation Mask for Cassegrains comes in 9 standard sizes. Each size is fully adjustable across a range in order to give a good fit for any telescope within its size range. Choose the GoldFocus Mask size which is correct for your telescope.
Follow the 3 steps below to select the correct size GoldFocus Mask for your telescope.
- Decide Between Outside or Inside Mount for Your Telescope.
- Measure the Outside or Inside Diameter of Your Telescope Objective Bezel Ring.
- Locate Your Measured Outside or Inside Diameter in the Table and Find the GoldFocus Mask Product Number at the Left of the Table.
Step 1 - Decide Between Outside or Inside Mount for Your Telescope
The GoldFocus Mask has mounting studs which hold the mask in place on the telescope objective bezel ring. The mounting studs can go either outside or inside your telescope objective bezel ring. See images below for examples of outside and inside mounting.
The GoldFocus Mask can be mounted directly to the objective bezel ring, a glare shield, or a dew shield. Choose the outside or inside mounting according to how you will be using the GoldFocus Mask.
Note: The Inside Mount of the GoldFocus Mask requires clearance inside the bezel ring to a minimum depth of 15 mm (0.6 inches) for the mounting studs to project inside the bezel ring. If your telescope does not have the clearance required for the Inside Mount, then you will need to choose the Outside Mount. If you have any doubt about the required inside clearance, then choose the Outside Mount.
Before proceeding to the next step, decide between Outside Mount or Inside Mount that is appropriate for your telescope.
Step 2 - Measure the Outside or Inside Diameter of Your Telescope Objective Bezel Ring
Measure the outside or inside diameter corresponding to which of Outside Mount or Inside Mount you have chosen for your telescope. Measure the objective bezel ring, glare shield, or dew shield according to how you will be mounting the GoldFocus Mask. Use a ruler or tape measure to measure the diameter accurate to about 0.1 or 1/8 inches or 2-3 mm. See the image below for an illustration of how to measure the outside or inside diameter.
Step 3 - Locate Your Measured Outside or Inside Diameter in the Table and Find the GoldFocus Mask Product Number at the Left of the Table
Using the appropriate table below for either Inches or Millimeters measurements, locate your measured outside or inside diameter in the range of sizes listed under the corresponding Outside Mount or Inside Mount column. Read the GoldFocus Mask Product Number at the left side of the row containing your measured diameter.
*** For Example Only - You Must Measure Your Own Telescope ***
Example 1 - Consider an 8" Schmidt-Cassegrain. Suppose the bezel ring projects out with ample clearance of over 15 mm (0.6 inches) from the front of the bezel ring back to the corrector lens. This telescope has enough clearance to use the Inside Mount. Suppose the measured inside diameter of the bezel ring is 9.1 inches. Look under the Inside Mount Diameter Range column in the table for GoldFocus Mask Sizes - Inches. The measured inside diameter of 9.1 inches falls in the range 8.1-10.0 inches under the Inside Mount Diameter Range column. The GoldFocus Mask Product Number on that row is G107 and that is the required size for this example telescope.
*** For Example Only - You Must Measure Your Own Telescope ***
Example 2 - Consider a 102 mm Maksutov-Cassegrain. Suppose the corrector lens is nearly flush with the front of the bezel ring so that there is little or no clearance from the front of the bezel ring back to the corrector lens. This telescope cannot use the Inside Mount and must use the Outside Mount. Suppose the measured outside diameter of the bezel ring is 113 mm. Look under the Outside Mount Diameter Range column in the table for GoldFocus Mask Sizes - Millimeters. The measured outside diameter of 113 mm falls in the range 90-118 and also in the range 108-146 under the Outside Mount Diameter Range column. You have a choice between two sizes and the smaller 90-118 is probably preferred. The GoldFocus Mask Product Number on that row is G50 and that is the required size for this example telescope.
GoldFocus Mask Custom Sizes
If you have special requirements for a GoldFocus Mask, you may inquire about a Custom GoldFocus Mask by e-mail at: info@goldastro.com
GoldFocus Mask Size Selection
GoldFocus Plus Collimation - Cassegrain
GoldFocus Mask Sizes - Inches
| GoldFocus Mask Product Number |
Outside Mount Diameter Range (Inches) |
Inside Mount Diameter Range (Inches) |
Add to Cart | Price (US $) |
| GC88 | 6.1 - 7.8 | 6.6 - 8.3 |
 |
$ 114.00 |
| GC97 | 7.0 - 8.6 | 7.4 - 9.1 |
|
$ 120.00 |
| GC107 | 7.6 - 9.5 | 8.1 - 10.0 |
|
$ 128.00 |
| GC119 | 8.4 - 10.6 | 8.9 - 11.1 |
|
$ 135.00 |
| GC127 | 9.3 - 11.3 | 9.8 - 11.9 |
|
$ 140.00 |
| GC137 | 9.9 - 12.4 | 10.4 - 12.8 |
|
$ 145.00 |
| GC147 | 10.8 - 13.3 | 11.3 - 13.9 |
|
$ 151.00 |
| GC167 | 11.7 - 15.4 | 12.1 - 15.9 |
|
$ 166.00 |
GoldFocus Plus Collimation - Cassegrain
GoldFocus Mask Sizes - Millimeters
| GoldFocus Mask Product Number |
Outside Mount Diameter Range (Millimeters) |
Inside Mount Diameter Range (Millimeters) |
Add to Cart | Price (US $) |
| GC88 | 156 - 197 | 168 - 210 |
|
$ 114.00 |
| GC97 | 177 - 219 | 189 - 231 |
|
$ 120.00 |
| GC107 | 194 - 242 | 207 - 255 |
|
$ 128.00 |
| GC119 | 214 - 269 | 226 - 282 |
|
$ 135.00 |
| GC127 | 237 - 288 | 250 - 301 |
|
$ 140.00 |
| GC137 | 252 - 314 | 265 - 326 |
|
$ 145.00 |
| GC147 | 274 - 339 | 286 - 352 |
|
$ 151.00 |
| GC167 | 296 - 390 | 308 - 403 |
|
$ 166.00 |
GoldFocus Analysis Software
The GoldFocus Analysis Software is included with each purchase of a GoldFocus Mask and is not available for separate purchase.
