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Adapters

Almost every imaging train problem in astrophotography — soft corners, elongated stars, a camera that will not come to focus — traces back to a few millimetres of the wrong adapter. David Astro carries adapters in Canada covering M42, M48, M54, M68, SCT and Nikon and Canon bayonet standards, along with barrel adapters in 1.25" and 2", all in stock and shipping from Canada.

Adapters are the one product category where buying blind is genuinely expensive. Our team calculates back-focus and thread compatibility for customers every day, so before you assemble a stack from guesswork, send us your components and we will specify the parts.

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William Optics Flat4 Draw Tube Adapter for FLT (Gold) for 2007-2016 Models

WO-AD4-A006-L00GD03

Securely connects the Flat4 Field Flattener to the draw tube Designed for William Optics FLT 98, 110, 132, and 152 models Compatible with telescop...

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William Optics Flat4 Draw Tube Adapter for GT102, FLT 132 - Black for 3" V-Power Focuser

WO-AD4-A006-L00BL03

Connects William Optics Flat4 Flattener to Draw Tube Designed for the 3" V-Power Focuser Compatible with GT102 & FLT 132 (2017 Models) Ensures...

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William Optics Flat4 Draw Tube Adapter for GT102, FLT 132 - Blue for 3" V-power Focuser

WO-AD4-A006-L00BU03

Connects Flat4 Flattener to 3" V-Power Focuser Compatible with William Optics GT102 & FLT 132 Engineered for 2017 Telescope Models Secure Thre...

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William Optics Longer adjusting adapter for FLAT68III, FLAT7A

WO-AD-M80-45-M48

Connects FLAT68III & FLAT7A Flatteners to M48 Imaging Trains Provides a Fixed 45mm Optical Length Input Thread: M80 x 0.75 Male Output Thread:...

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William Optics M48 Female to M42 Male Adapter

WO-YE-M48-42

Connects M48 Female Threads to M42 Male Threads Adds Only 5.3mm of Optical Path Length Standard 2" Filter Thread (M48x0.75) to T-Thread (M42x0.75)...

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William Optics M48 Push-in Nosepiece for WO 2" Diagonals & UniGuide Scope

WO-WD-DIG2A
1 in stock

Connects M48 Threaded Accessories to 2" Push-in Focusers Female M48 Threads for 2" Filter Attachment Adds a Fixed 36 mm of Optical Length Male M48...

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William Optics M63 Female to 2" Push-in Adapter for P-FLAT6AIII

WO-YE-M63F-2IN-PI
1 in stock

Connects P-FLAT6AIII Flattener to 2" Focuser Female M63 Threads for Flattener Connection Male 2" Push-in Barrel for Focuser Internal M48 Female Th...

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William Optics M63(M) to M48(M) Photo Adapter

WO-P-PAM-63-48

Adds 80mm of Optical Length Connects to M63 Female Threads Outputs to M48 Male T-Threads Enables Focus Without a Field Flattener Designed for Will...

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William Optics M92 to M63 Adapter for William Optics FLT91
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William Optics M92 to M63 Adapter for William Optics FLT91

WO-YE-M92-63

Connects William Optics FLT91 Telescope to Flat6AIII Flattener Input Thread: M92 Male Output Thread: M63 Female Optical Path Length: 10.5 mm De...

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William Optics Micro 4/3 48mm T-Mount for Olympus - Black

WO-TM-MFT-M48
3 in stock

Connects M48 Correctors to Olympus Micro 4/3 Cameras Fixed 35.6 mm Optical Length for Precise Back Focus Light-In Connection: M48 (Female) Thread ...

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William Optics SCT Connection for WO Diagonals - Gold

WO-D-SCT-TA

Connects M50.8 Male to M48 Female Threads Adds 13.8 mm of Optical Length Female Thread: M50.8 Male Thread: M48 Signature William Optics Gold Anodi...

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William Optics STL Adapter for FLT Flattener

WO-P-STL

Connects SBIG STL-11000 Series CCD Cameras Attaches to P-FLAT68 Field Flatteners via M80 Female Thread Provides a Precise 69 mm Optical Path Lengt...

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William Optics Super High Precision COPPER T-Mount for Canon EOS Full Frame

WO-YE-TR-BR48-C
1 in stock

Solid Copper Construction for Maximum Rigidity M48 (2") Female Thread for Wide-Field Correctors Connects to Canon EOS Camera Bodies Precise 10.6 m...

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William Optics Super High Precision COPPER T-Mount for Nikon Full Frame

WO-YE-TR-BR48-N

Solid Copper Construction for Maximum Rigidity M48 x 0.75 Female Thread for Wide-Field Correctors Designed for Nikon Full-Frame DSLR and Mirrorles...

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ZWO Adapter - 2mm M54(M)/M48(F)

ZWO-M54M-M48F-2
16 in stock

Connects M54 Filter Wheels to M48 Accessories Adds Only 2 mm to Optical Path Maintains 55 mm Back Focus Standard Knurled Edge for Secure Grip Desi...

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ZWO M42 Adapter for OAG

ZWO-M42-adapter
1 in stock

M42 adapter for main imaging camera Specifications

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ZWO M42 Extension - 21mm

ZWO-T2-EXT-21
29 in stock

Adds exactly 21mm of spacing to an M42 optical train M42x0.75 female threads on one side, male threads on the other Machined aluminum with a black...

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ZWO M42 Plate for CAA Rotator

ZWO-CAA-PLATE-M42
10 in stock

Converts ZWO CAA Rotator to M42 T-Threads Maintains 55mm Backfocus Standard CAA with M42 Plate Stays at 16.5mm Ideal for ASI533, ASI2600, and Othe...

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ZWO M42-M48 Adapter - 16.5mm

ZWO-T2-M48-16.5
24 in stock

Adds a precise 16.5mm of optical path length Connects male M42 (T2) threads to female M48 threads Essential for achieving standard 55mm back focus...

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ZWO M42e to M48i Extension - 22.5mm

ZWO-M42-M48-22.5
5 in stock

Establishes precise 55mm back focus with specific ZWO camera/filter wheel combinations Provides exactly 22.5 mm of optical path length Connects M4...

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ZWO M48 Extension - 16.5mm

ZWO-M48-EXT16.5
20 in stock

Adds exactly 16.5 mm of spacing to an M48 imaging train M48x0.75 male and female threads Wide 43.2 mm clear aperture prevents vignetting with full...

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ZWO M48-M42 Adapter
$12.00 - $12.00
$12.00
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ZWO M48-M42 Adapter

ZWO-M48-M42
10 in stock

Converts female M48x0.75 threads to female M42x0.75 T-threads Adds 0mm of optical path length to the imaging train Durable black anodized aluminum...

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ZWO M54 Adapter replacing EFW

ZWO-D70-M54F
2 in stock

Replaces the ZWO EFW to achieve 55mm back focus with the OAG-L Adds only 15 mm of optical length to the imaging train Holds a single 2-inch mounte...

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ZWO M54 Extension - 16.5mm

ZWO-M54-M54-16.5
2 in stock

Optical Length: 16.5mm Connection Side 1: M54x0.75 Male Thread Connection Side 2: M54x0.75 Female Thread Material: Anodized Aluminum Descriptio...

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Understanding Thread Standards and Back-Focus

An adapter does two things at once: it changes the connection type, and it changes the distance between your corrector and your sensor. The second effect is the one that causes trouble, because most reducers and flatteners have a back-focus tolerance of about one millimetre.

  • M42 (T-thread, 0.75 mm pitch): The long-standing standard for camera adapters. Its clear aperture will vignette sensors larger than APS-C, so full-frame imaging trains should avoid it.
  • M48 (2" thread, 0.75 mm pitch): The practical choice for APS-C and full-frame sensors, with enough clear aperture to avoid mechanical vignetting.
  • M54 and M68: Larger-diameter threads used by heavier astrographs and larger-format correctors where rigidity and aperture both matter.
  • SCT 2"-24 TPI: The rear-cell thread on Schmidt-Cassegrains; requires a specific adapter to reach M42 or M48 for imaging.
  • Bayonet adapters: Canon EF and Nikon F adapters place a DSLR or mirrorless body at the correct flange distance, typically 44 mm and 46.5 mm respectively.
  • Fine-tuning spacers: 0.5 mm, 1 mm and 2 mm shims that let you land exactly on a corrector's specified spacing rather than near it.

Why Choose David Astro for Adapters

An adapter is a cheap part that determines whether an expensive telescope performs. We treat it that way.

  • Free back-focus calculation: Give us your camera, filter thickness, reducer and telescope and we will return a component list with the total spacing worked out.
  • Filter thickness accounted for: Glass in the light path shifts focus by roughly one third of its thickness, and we include that in the calculation rather than leaving you to discover it.
  • Male and female threads identified: We specify the gender and standard on both ends, which is the detail most listings omit.
  • Deep Canadian stock: Hundreds of adapters held domestically, so a missing 10 mm spacer does not cost you three weeks of clear sky.
  • Authorized dealer: Genuine manufacturer parts with full warranty, shipped from Canada without duties for Canadian buyers.

Adapters in Canada — Frequently Asked Questions

How do I calculate my back-focus?
Add your camera's sensor-to-flange distance, any filter wheel or off-axis guider, the filter's optical shift, and every spacer between the camera and the corrector. That total must match the corrector's specified figure, usually 55 mm for a standard reducer.
Should I use M42 or M48?
Use M48 for any sensor larger than APS-C. M42 has enough clear aperture for smaller sensors but will mechanically vignette a full-frame chip regardless of the optics ahead of it.
Do filters change my spacing?
Yes. A filter shifts the focal plane by about one third of its glass thickness. A 3 mm filter adds roughly 1 mm to the effective optical path, which is enough to matter at a 55 mm target.
What if I order the wrong adapter?
Contact us with your setup before ordering and we will confirm the parts. That is a faster path than exchanges, and it is a service we provide free.

Send us your imaging train

We will calculate the spacing and specify every adapter you need. Canadian stock, no guesswork.