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Tri-Bahtinov, Isolation Mask & Dust Cap Kit
Black component photographs shown. Shape varies by telescope model.
Three-piece kit, image 1 of 5.Focus and alignment system
Check focus and alignment, isolate one pattern when needed, and cover the telescope when you finish. A matched three-piece system with no shield required.
Model, fit, or choosing parts — we can help before you order.
Focus and alignment system
Includes the tri-Bahtinov mask, isolation mask and dust cap. A dew shield is sold separately.
Creates three diffraction patterns to help you judge focus and optical alignment on a bright star.
Used with the tri-Bahtinov mask to cover two sectors and examine one pattern at a time.
Covers the telescope or matching shield between sessions to help keep dust off the front optics.
See how focusing masks and a cap work with a matching shield. Read the telescope accessory guide, compare dew shields, or browse matched accessory kits. Choose the same telescope model for every matching part.
Designed to work together
The masks and dust cap fit both your telescope directly and the matching StargazeWorks dew shield. Choose pieces for the same telescope model and use the setup that suits your session.
Use the tri-Bahtinov directly on your telescope or with a matching StargazeWorks shield, sold separately.
Add the isolation mask when you want to examine one of the three diffraction patterns. Follow your telescope’s instructions for adjustments.
Remove the focusing masks before observing or imaging. Use the cap on the telescope or matching shield when you finish.
Preview a color
Real parts, in use
Original photographs show a Celestron SCT example. Check the captions for the parts shown.
Made for your model
Select the full model name in the menu above, then choose your color. Similar apertures can have different fittings.
Sky-Watcher Explorer 150P / 150PDS and Quattro 150P use different fittings. Pick the one you own. Need help finding your model?
Before your first night out
Printed to order in carbon-fiber-reinforced PETG (CF-PETG), with a matte finish and fine print layer lines.
No. The masks and cap fit the telescope directly. They also fit the matching StargazeWorks shield if you add one later.
The tri-Bahtinov produces three diffraction patterns. The isolation mask covers two sectors so you can examine one at a time. Use it over the tri-Bahtinov; it does not replace it.
Choose the full telescope model name, then your color. Similar apertures can have different fittings. Sky-Watcher Explorer 150P / 150PDS and Quattro 150P use different parts; select the one you own. Contact us if your model is unclear or not listed.
If a part does not fit the telescope model on your order, contact us within 30 days of delivery. Confirmed fit or manufacturing issues receive a replacement at no charge. The guarantee does not cover selecting the wrong telescope model.
Normally dispatches in 1–3 business days. U.S. standard shipping is $8, or free on orders of $70 or more, with an estimated 3–5 business days in transit after dispatch. Express shipping is $15, with an estimated 1–2 business days in transit. Delivery estimates are shown at checkout.
Tell us your model, which StargazeWorks parts you already have, and what you want to do. We can help you choose the right pieces or check how your setup works together. Use the question form on this page or contact us before ordering.
Let’s get your setup right
Tell us your model, which StargazeWorks parts you already have, and what you want to do. We can help you choose the right pieces or check how your setup works together. Send your question here. We’ll reply by email.
Normally dispatches in 1–3 business days.
On orders $70+. See delivery details.
Free replacement for confirmed fit or manufacturing issues reported within 30 days for the model ordered. Full policy.