3D Astro Bahtinov Focus Mask - 170mm ID
- This item is currently on backorder from the manufacturer.
- Orders are fulfilled in the order they are received once inventory arrives.
Stock count is accurate & shown in real time.
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
Contiguous US / Lower 48:
Free shipping applies to orders over $50 using our chosen carrier/method. Faster paid options are available at checkout.
Alaska, Hawaii & US Territories:
Free shipping applies to many—but not all—products. Enter your ZIP code in cart or upon checkout to confirm options and costs.
International:
International orders do not qualify for free shipping. Shipping, duties, brokerage, tariffs, and taxes are the customer’s responsibility. Some items may be restricted due to export, size, or manufacturer limitations.
3D Astro Bahtinov Focus Mask (170mm Inside Diameter)
This focus mask features a 170mm Inside Diameter (ID). It is designed to slide easily over the front of your telescope's dew shield or lens cell.
With the mask on, you can see a diffraction spike pattern. Focus until you achieve a symetrical pattern. Once the best focus has been achieved, you can remove the mask and use the scope as normal. This mask is deliberately designed to fit loosely over the front dewshield so that it can easily be removed when focusing is finished. It doesn't fit firmly like an end cap, this is to ensure the imaging setup isn’t disturbed when removing. If you're unsure which size you need, follow the "Selecting the Correct Bahtinov Mask Size" steps below to properly measure your telescope at home.
- 3D printed from PLA
- Color: Silver-gray (subject to change without notice)
Selecting the Correct Bahtinov Mask Size
- Measure the outside diameter of your telescope tube or dew shield at the front (sky-end) using a caliper, ruler, or tape measure.
- Measure the widest point across the center, from the outside edge of one side to the outside edge of the other.
- Use millimeters (mm) whenever possible. If measuring in inches, multiply by 25.4 to convert to mm.
- Choose a Bahtinov mask with an inside diameter 1–3 mm larger than your measured diameter.
- The mask should rest loosely on the dew shield—it is not intended to fit tightly like a lens cap.
- Example: A dew shield measuring 108 mm in outside diameter should use a 110 mm Bahtinov mask.
- Double-check your measurements before ordering to ensure the best fit and avoid unnecessary returns.
Important Notes
- Please note that this is a 3d printed product typically made of a plastic material (see item description above for the exact material used).
- The cosmetic finish on 3d printed items will vary and will not be as polished or smooth as metal items. It is not uncommon to have imperfections such as scratches, scuff marks, or inconsistent surface finish. However, these have no functional impact on the use of the item.
- 3d printed items should not be subject to very high operating temperatures (for example, left in storage in hot sheds, cars, etc.) and exposure to sunlight should be minimized.
- Notes on some commonly used 3d printing materials:
-
- PLA: Most commonly used material in 3d printing; derived from corn or sugarcane so is biodegradable; basic PLA should not be exposed to over 125° F and exposure to sunlight should be minimized; available in custom formulations that can withstand higher temperatures and solar exposure.
- PETG: Another very popular 3d printing material; has smoother surface finish; water resistant; should not be exposed to temperatures usually above 160° F.
- TPU: More expensive but more durable; is elastic and resistant to low temperatures, abrasion, oil, chemicals and wearing; can withstand ambient temperatures up to 175º F
- ABS: A strong material used for strong and durable parts; able to withstand temperatures of up to 200º F
For more technical info about 3d materials, please visit this link.
-
Other Information
- Country of Manufacture: United States
3D Astro Bahtinov Focus Mask (170mm Inside Diameter)
This focus mask features a 170mm Inside Diameter (ID). It is designed to slide easily over the front of your telescope's dew shield or lens cell.
With the mask on, you can see a diffraction spike pattern. Focus until you achieve a symetrical pattern. Once the best focus has been achieved, you can remove the mask and use the scope as normal. This mask is deliberately designed to fit loosely over the front dewshield so that it can easily be removed when focusing is finished. It doesn't fit firmly like an end cap, this is to ensure the imaging setup isn’t disturbed when removing. If you're unsure which size you need, follow the "Selecting the Correct Bahtinov Mask Size" steps below to properly measure your telescope at home.
- 3D printed from PLA
- Color: Silver-gray (subject to change without notice)
Selecting the Correct Bahtinov Mask Size
- Measure the outside diameter of your telescope tube or dew shield at the front (sky-end) using a caliper, ruler, or tape measure.
- Measure the widest point across the center, from the outside edge of one side to the outside edge of the other.
- Use millimeters (mm) whenever possible. If measuring in inches, multiply by 25.4 to convert to mm.
- Choose a Bahtinov mask with an inside diameter 1–3 mm larger than your measured diameter.
- The mask should rest loosely on the dew shield—it is not intended to fit tightly like a lens cap.
- Example: A dew shield measuring 108 mm in outside diameter should use a 110 mm Bahtinov mask.
- Double-check your measurements before ordering to ensure the best fit and avoid unnecessary returns.
Important Notes
- Please note that this is a 3d printed product typically made of a plastic material (see item description above for the exact material used).
- The cosmetic finish on 3d printed items will vary and will not be as polished or smooth as metal items. It is not uncommon to have imperfections such as scratches, scuff marks, or inconsistent surface finish. However, these have no functional impact on the use of the item.
- 3d printed items should not be subject to very high operating temperatures (for example, left in storage in hot sheds, cars, etc.) and exposure to sunlight should be minimized.
- Notes on some commonly used 3d printing materials:
-
- PLA: Most commonly used material in 3d printing; derived from corn or sugarcane so is biodegradable; basic PLA should not be exposed to over 125° F and exposure to sunlight should be minimized; available in custom formulations that can withstand higher temperatures and solar exposure.
- PETG: Another very popular 3d printing material; has smoother surface finish; water resistant; should not be exposed to temperatures usually above 160° F.
- TPU: More expensive but more durable; is elastic and resistant to low temperatures, abrasion, oil, chemicals and wearing; can withstand ambient temperatures up to 175º F
- ABS: A strong material used for strong and durable parts; able to withstand temperatures of up to 200º F
For more technical info about 3d materials, please visit this link.
-
3D Astro Bahtinov Focus Mask (170mm Inside Diameter)
This focus mask features a 170mm Inside Diameter (ID). It is designed to slide easily over the front of your telescope's dew shield or lens cell.
With the mask on, you can see a diffraction spike pattern. Focus until you achieve a symetrical pattern. Once the best focus has been achieved, you can remove the mask and use the scope as normal. This mask is deliberately designed to fit loosely over the front dewshield so that it can easily be removed when focusing is finished. It doesn't fit firmly like an end cap, this is to ensure the imaging setup isn’t disturbed when removing. If you're unsure which size you need, follow the "Selecting the Correct Bahtinov Mask Size" steps below to properly measure your telescope at home.
- 3D printed from PLA
- Color: Silver-gray (subject to change without notice)
Selecting the Correct Bahtinov Mask Size
- Measure the outside diameter of your telescope tube or dew shield at the front (sky-end) using a caliper, ruler, or tape measure.
- Measure the widest point across the center, from the outside edge of one side to the outside edge of the other.
- Use millimeters (mm) whenever possible. If measuring in inches, multiply by 25.4 to convert to mm.
- Choose a Bahtinov mask with an inside diameter 1–3 mm larger than your measured diameter.
- The mask should rest loosely on the dew shield—it is not intended to fit tightly like a lens cap.
- Example: A dew shield measuring 108 mm in outside diameter should use a 110 mm Bahtinov mask.
- Double-check your measurements before ordering to ensure the best fit and avoid unnecessary returns.
Important Notes
- Please note that this is a 3d printed product typically made of a plastic material (see item description above for the exact material used).
- The cosmetic finish on 3d printed items will vary and will not be as polished or smooth as metal items. It is not uncommon to have imperfections such as scratches, scuff marks, or inconsistent surface finish. However, these have no functional impact on the use of the item.
- 3d printed items should not be subject to very high operating temperatures (for example, left in storage in hot sheds, cars, etc.) and exposure to sunlight should be minimized.
- Notes on some commonly used 3d printing materials:
-
- PLA: Most commonly used material in 3d printing; derived from corn or sugarcane so is biodegradable; basic PLA should not be exposed to over 125° F and exposure to sunlight should be minimized; available in custom formulations that can withstand higher temperatures and solar exposure.
- PETG: Another very popular 3d printing material; has smoother surface finish; water resistant; should not be exposed to temperatures usually above 160° F.
- TPU: More expensive but more durable; is elastic and resistant to low temperatures, abrasion, oil, chemicals and wearing; can withstand ambient temperatures up to 175º F
- ABS: A strong material used for strong and durable parts; able to withstand temperatures of up to 200º F
For more technical info about 3d materials, please visit this link.
-
Other Information
- Country of Manufacture: United States
3D Astro Bahtinov Focus Mask - 170mm ID