Product Overview
Give your long-focus scope a wider, brighter personality. The Antares 2" 0.7× reducer threads on like a standard 2" filter and shortens your telescope’s effective focal length, opening up larger swaths of sky and cutting exposure times—perfect for galaxies, nebulae, and sweeping star fields.
Why you’ll like it
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0.7× class reduction at 66 mm working distance (from the reducer’s rear lens to the sensor).
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Tunable field of view: add spacers to increase reduction for even faster imaging.
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2" format with standard filter threads for easy integration with cameras, wheels, and diagonals.
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High-quality, fully multi-coated optics for crisp, contrasty images.
How spacing changes the reduction
As you increase the spacing (back focus), the reduction increases (wider field, faster f/ratio). Use the table below as a practical guide. Values are approximate and based on the common reducer relationship around this class; plate solve to confirm your exact result.
Spacer → Reduction quick reference (sensor distance measured from reducer to sensor)
| Added Spacer vs 66 mm | Back Focus (mm) | Approx. Reduction | f/10 Becomes |
|---|---|---|---|
| +0 mm | 66 | ~0.70× | f/7.0 |
| +5 mm | 71 | ~0.68× | f/6.8 |
| +10 mm | 76 | ~0.66× | f/6.6 |
| +15 mm | 81 | ~0.64× | f/6.4 |
| +20 mm | 86 | ~0.61–0.62× | f/6.1–f/6.2 |
Tips
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Start at 66 mm for the nominal 0.7× experience.
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Add spacers in small steps and confirm with a quick plate solve to dial in framing and star shape.
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Very large spacing can push the system too hard and may introduce edge aberrations—balance speed with image quality.
Examples of FOV when used with some cameras
ASI294 (4.63 µm, 4144×2822)
| Added Spacer vs 66 mm | BF (mm) | Reduction (×) | Eff. FL (mm) | Pixel Scale (″/px) | FOV (°) |
|---|---|---|---|---|---|
| +0 | 66 | 0.70 | 700 | 1.364 | 1.570 × 1.069 |
| +5 | 71 | 0.68 | 677.3 | 1.410 | 1.623 × 1.105 |
| +10 | 76 | 0.65 | 654.5 | 1.460 | 1.679 × 1.142 |
| +15 | 81 | 0.63 | 631.8 | 1.516 | 1.740 × 1.184 |
| +20 | 86 | 0.61 | 609.1 | 1.572 | 1.802 × 1.227 |
ASI533 (3.76 µm, 3008×3008)
| Added Spacer vs 66 mm | BF (mm) | Reduction (×) | Eff. FL (mm) | Pixel Scale (″/px) | FOV (°) |
|---|---|---|---|---|---|
| +0 | 66 | 0.70 | 700 | 1.109 | 0.927 × 0.927 |
| +5 | 71 | 0.68 | 677.3 | 1.147 | 0.958 × 0.958 |
| +10 | 76 | 0.65 | 654.5 | 1.186 | 0.991 × 0.991 |
| +15 | 81 | 0.63 | 631.8 | 1.228 | 1.025 × 1.025 |
| +20 | 86 | 0.61 | 609.1 | 1.273 | 1.063 × 1.063 |
ASI585 (2.90 µm, 3840×2160)
| Added Spacer vs 66 mm | BF (mm) | Reduction (×) | Eff. FL (mm) | Pixel Scale (″/px) | FOV (°) |
|---|---|---|---|---|---|
| +0 | 66 | 0.70 | 700 | 0.854 | 0.912 × 0.513 |
| +5 | 71 | 0.68 | 677.3 | 0.883 | 0.943 × 0.531 |
| +10 | 76 | 0.65 | 654.5 | 0.914 | 0.977 × 0.550 |
| +15 | 81 | 0.63 | 631.8 | 0.946 | 1.010 × 0.568 |
| +20 | 86 | 0.61 | 609.1 | 0.982 | 1.048 × 0.589 |
