Black tri-bahtinov mask photographed separately

Telescope Tri-Bahtinov Focus & Collimation Mask

Meade ETX-90 Mak / Black

$23.99

Product detail1 component

Tri-Bahtinov maskPhoto

Black component photographs shown. Shape varies by telescope model.

Tri-Bahtinov mask, image 1 of 1.

Telescope Tri-Bahtinov Focus & Collimation Mask

Focus and alignment

Telescope Tri-Bahtinov Focus & Collimation Mask

Check three diffraction patterns on a bright star to help judge focus and optical alignment. Use the mask on your telescope directly or in the matching shield.

$23.99

Choose your telescope first to unlock color choices. Price varies by model.

Telescope Model

Color

See all four colors in the renders below ↓

U.S. standard shipping: $8 under $70; free at $70 or more. Delivery details.

Ask a question about your setup →

Model, fit, or choosing parts — we can help before you order.

Focus and alignment

Made for your next clear night.

Includes one tri-Bahtinov mask. The isolation mask, shield and dust cap are sold separately.

01

Tri-Bahtinov mask

Creates three diffraction patterns to help you judge focus and optical alignment on a bright star.

Build your setup

Plan a setup for focus, alignment and light control. 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

One system. With or without the shield.

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.

01

Fit the mask

Place it directly on your telescope or in the matching StargazeWorks shield.

02

Check the patterns

Use a bright star to judge focus and alignment. Follow your telescope's instructions for any collimation adjustment.

03

Observe or image

Remove the focusing masks when your setup is ready.

Black — CAD product/assembly illustration — Illustrative CAD views show one model example. Geometry varies by telescope. Rendered colors are approximate; choose your order color above.

Brick Red — CAD product/assembly illustration — Illustrative CAD views show one model example. Geometry varies by telescope. Rendered colors are approximate; choose your order color above.

Real parts, in use

See the system on a telescope.

Original photographs show a Celestron SCT example. Check the captions for the parts shown.

Tri-Bahtinov and isolation masks fitted directly to a real Celestron SCT. Telescope is not included. The isolation mask is sold separately.

Made for your model

Made for your telescope.

Select the full model name in the menu above, then choose your color. Similar apertures can have different fittings.

Apertura AD8 Dob
Celestron 130EQ / 130SLT
Celestron 4SE Mak
Celestron 6in Dob
Celestron 8in Newt
Celestron C11 SCT / CPC 1100 / AVX 11 SCT
Celestron C5 SCT / 5SE SCT
Celestron C6 SCT / 6SE SCT / Evo 6 SCT
Celestron C8 SCT / 8SE SCT / Evo 8 SCT / CPC 800 / EdgeHD 8 / AVX 8 SCT / CGX 800
Celestron C9.25 SCT / EdgeHD 925 / CPC 925 / Evo 9.25
Meade ETX-105 Mak
Meade ETX-125 Mak
Meade ETX-90 Mak
Meade LX200 10in ACF
Meade LX200 8in SCT
Meade LX90 10in ACF
Meade LX90 8in SCT
Orion XT10 10in Dob / Apertura AD10 Dob / Zhumell Z10 Dob
Orion XT8 8in Dob
Sky-Watcher 127 Mak
Sky-Watcher 130P
Sky-Watcher 150 Mak
Sky-Watcher 150P / 150PDS
Sky-Watcher 200P Dob
Sky-Watcher 250P Dob
Sky-Watcher Flx 200P
StarSense 10in Dob
SW Quattro 150P
Zhumell Z8 Dob

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

A few useful details.

Printed to order in carbon-fiber-reinforced PETG (CF-PETG), with a matte finish and fine print layer lines.

Ask us about your telescope

What does the tri-Bahtinov pattern show?

The three grating sectors produce separate diffraction patterns. They help you inspect focus and alignment; the mask does not adjust the telescope for you. Follow your telescope’s instructions for collimation.

Do I need the isolation mask too?

The tri-Bahtinov works on its own. Add the isolation mask when you want to cover two sectors and inspect one pattern at a time. It is sold separately or included in a kit.

Which telescope model should I choose?

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.

What if the fit is not right?

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.

When will it arrive?

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.

Can you help me choose or use the system?

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

Ask us anything.

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.