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Optical Accessories

Optical accessories are what turn one telescope into several. The same optical tube can be a wide-field imaging refractor, a high-power planetary instrument or a comfortable binocular-view visual scope depending on what you put behind it. David Astro carries a deep selection of eyepieces, diagonals, Barlows, reducers, flatteners, binoviewers and correctors in Canada, held in Canadian stock.

Our team uses this equipment on our own telescopes, so the advice you get is based on what actually works at a given focal ratio and under a given sky, not on a spec sheet. If you are deciding between two focal lengths or wondering whether a corrector will help your optic, ask us before you order.

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CA$193.00 - CA$193.00
CA$193.00
CA$193.00 - CA$193.00
CA$193.00

TeleVue Plössl 25mm 50° Eyepiece - 1.25"

TV-EAP-25.0

25mm Focal Length 50° Apparent Field of View 1.25" Diameter Barrel 17mm Eye Relief 21.2mm Field Stop Description FAQ Specifications In the Box ...

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CA$193.00 - CA$193.00
CA$193.00
CA$193.00 - CA$193.00
CA$193.00
CA$246.00 - CA$246.00
CA$246.00
CA$246.00 - CA$246.00
CA$246.00

TeleVue Plössl 32mm 50° Eyepiece - 1.25"

TV-EPL-32.0
2 in stock

32mm Focal Length 50° Apparent Field of View 1.25" Diameter Barrel 22mm Eye Relief 27mm Field Stop Description FAQ Specifications In the Box Do...

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CA$246.00 - CA$246.00
CA$246.00
CA$246.00 - CA$246.00
CA$246.00
CA$246.00 - CA$246.00
CA$246.00
CA$246.00 - CA$246.00
CA$246.00

TeleVue Plössl 40mm 43° Eyepiece - 1.25"

TV-EPL-40.0
1 in stock

40mm Focal Length 43° Apparent Field of View 1.25" Diameter Barrel 28mm Eye Relief 27mm Field Stop Description FAQ Specifications In the Box Do...

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CA$246.00 - CA$246.00
CA$246.00
CA$246.00 - CA$246.00
CA$246.00
CA$406.00 - CA$406.00
CA$406.00
CA$406.00 - CA$406.00
CA$406.00

TeleVue Plössl 55mm 50° Eyepiece - 2"

TV-EPL-55.0

55mm Focal Length 50° Apparent Field of View 2" Diameter Barrel 38mm Eye Relief 46mm Field Stop Description FAQ Specifications In the Box Downl...

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CA$406.00 - CA$406.00
CA$406.00
CA$406.00 - CA$406.00
CA$406.00
Wanderer Astro SFW50/SFW50S Filter Shim for 50mm Filters thinner than 2.5mm
CA$25.00 - CA$25.00
CA$25.00
CA$25.00 - CA$25.00
CA$25.00

Wanderer Astro Filter Shim for 50mm Filters

WA-WSFW50-FS

Designed for SFW50 & SFW50S Filter Wheels Adapts 50mm Unmounted Filters Thinner than 2.5mm Ensures Accurate and Stable Filter Seating Prevents...

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CA$25.00 - CA$25.00
CA$25.00
CA$25.00 - CA$25.00
CA$25.00
Wanderer Astro ND Filter for WandererCover
CA$7.00 - CA$13.00
CA$7.00 - CA$13.00
CA$7.00 - CA$13.00
CA$7.00

Wanderer Astro ND Filter for WandererCover

Options available

Available in 7 sizes from 80mm to 240mm Designed for WandererCover V4-EC and V4-EC IR Enables Calibrated Flat Frames with Sensitive Cameras Reduce...

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CA$7.00 - CA$13.00
CA$7.00 - CA$13.00
CA$7.00 - CA$13.00
CA$7.00
William Optics 1.25" 90° Erect Prism for Cat 61 WIFD
CA$219.00 - CA$219.00
CA$219.00
CA$219.00 - CA$219.00
CA$219.00

William Optics 1.25" 90° Erect Prism for Cat 61 WIFD

WO-D-EP90-125-RC61
1 in stock

Provides a fully corrected, erect image for terrestrial viewing Comfortable 90° viewing angle Standard 1.25" barrel accepts most astronomical eyep...

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CA$219.00 - CA$219.00
CA$219.00
CA$219.00 - CA$219.00
CA$219.00
William Optics 2" 90° Dura Bright Dielectric Diagonal for SCT threaded Scope
CA$286.00 - CA$286.00
CA$286.00
CA$286.00 - CA$286.00
CA$286.00

William Optics 2" 90° Dura Bright Dielectric Diagonal for SCT threaded Scope

WO-D-DIG2D-C-DB-SCT
1 in stock

Enables use of 2-inch eyepieces for wide-field views 90° viewing angle for comfortable observing at the zenith Dura-Bright dielectric coatings for...

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CA$286.00 - CA$286.00
CA$286.00
CA$286.00 - CA$286.00
CA$286.00
CA$81.00 - CA$81.00
CA$81.00
CA$81.00 - CA$81.00
CA$81.00

William Optics 2x Barlow Nosepiece for Binoviewer

WO-E-BINO-B2
6 in stock

Provides 2x magnification Enables binoviewers to reach focus in most telescopes Standard 1.25" nosepiece format Threads directly onto the binoview...

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CA$81.00 - CA$81.00
CA$81.00
CA$81.00 - CA$81.00
CA$81.00
CA$152.00 - CA$152.00
CA$152.00
CA$152.00 - CA$152.00
CA$152.00

William Optics 45° Erecting Prism - 1.25"

WO-D-EP125
6 in stock

Provides a fully corrected image (upright and left-right correct) Comfortable 45° viewing angle for terrestrial observation Fits standard 1.25" fo...

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CA$152.00 - CA$152.00
CA$152.00
CA$152.00 - CA$152.00
CA$152.00
CA$160.00 - CA$160.00
CA$160.00
CA$160.00 - CA$160.00
CA$160.00

William Optics 90° Erect Prism - 1.25"

WO-D-EP90-125II
5 in stock

Provides a fully corrected, upright, and non-reversed image Designed for 1.25" focusers and eyepieces 90° viewing angle for comfortable observing ...

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CA$160.00 - CA$160.00
CA$160.00
CA$160.00 - CA$160.00
CA$160.00
CA$190.00 - CA$190.00
CA$190.00
CA$190.00 - CA$190.00
CA$190.00

William Optics 99% Dielectric Dura Bright Diagonal - 1.25"

WO-D-125D-C-DB
1 in stock

1.25" Barrel Diameter 99% Dielectric Coated Mirror 1/12λ Mirror Surface Accuracy 12mm Thick Mirror Substrate 100% Real Carbon Fiber Side Plates ...

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CA$190.00 - CA$190.00
CA$190.00
CA$190.00 - CA$190.00
CA$190.00
CA$228.00 - CA$228.00
CA$228.00
CA$228.00 - CA$228.00
CA$228.00

William Optics 99% Dielectric Dura Bright Diagonal - 2"

WO-D-DIG2D-C-DB
3 in stock

2" Barrel with 90° Viewing Angle 99% Reflectivity Dielectric Coatings 1/12th Wave Precision Polished Mirror 12mm Thick Mirror Substrate for Therma...

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CA$228.00 - CA$228.00
CA$228.00
CA$228.00 - CA$228.00
CA$228.00
CA$384.00 - CA$384.00
CA$384.00
CA$384.00 - CA$384.00
CA$384.00

William Optics Adjustable Flat61 for Z61

WO-P-FLAT61A
1 in stock

1.0x Flattener Power Designed for William Optics Zenithstar 61 Full-Frame Sensor Coverage Adjustable Back Focus Mechanism M54 Telescope Thread &am...

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CA$384.00 - CA$384.00
CA$384.00
CA$384.00 - CA$384.00
CA$384.00
CA$371.00 - CA$371.00
CA$371.00
CA$371.00 - CA$371.00
CA$371.00

William Optics Adjustable Flat6AIII

WO-P-FLAT6AIII
2 in stock

0.8x Focal Reducer & Field Flattener Optimized for GT71, GT81, Z81 & Z103 Refractors Illuminates Full-Frame Sensors Adjustable Back Focus ...

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CA$371.00 - CA$371.00
CA$371.00
CA$371.00 - CA$371.00
CA$371.00
CA$480.00 - CA$480.00
CA$480.00
CA$480.00 - CA$480.00
CA$480.00

William Optics Adjustable Flat6AIII for FLT91

WO-P-FLAT6AIII-M92

Dedicated Field Flattener for the William Optics FLT91 Telescope Corrects Field Curvature for Pinpoint Stars Edge-to-Edge Integrated Adjustment Ri...

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CA$480.00 - CA$480.00
CA$480.00
CA$480.00 - CA$480.00
CA$480.00
CA$384.00 - CA$384.00
CA$384.00
CA$384.00 - CA$384.00
CA$384.00

William Optics Adjustable Flat73A for Z73

WO-P-FLAT73A
1 in stock

Designed specifically for the William Optics ZenithStar 73 APO Delivers a 1.0x, perfectly flat field across full-frame sensors Connects to the Z73...

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CA$384.00 - CA$384.00
CA$384.00
CA$384.00 - CA$384.00
CA$384.00
CA$409.00 - CA$409.00
CA$409.00
CA$409.00 - CA$409.00
CA$409.00

William Optics Adjustable Reducer Flattener Flat61R for Z61

WO-P-FLAT61R

Adjustable reducer and field flattener for William Optics Z61 telescope Improves image sharpness and reduces distortion Description ...

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CA$409.00 - CA$409.00
CA$409.00
CA$409.00 - CA$409.00
CA$409.00
CA$409.00 - CA$409.00
CA$409.00
CA$409.00 - CA$409.00
CA$409.00

William Optics Adjustable Reducer Flattener Flat73R for Z73

WO-P-FLAT73R

Reduces focal length by a factor of 0.8x Designed for the William Optics Zenithstar 73 telescope Provides edge-to-edge flat field for full-frame s...

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CA$409.00 - CA$409.00
CA$409.00
CA$409.00 - CA$409.00
CA$409.00
CA$509.00 - CA$509.00
CA$509.00
CA$509.00 - CA$509.00
CA$509.00

William Optics Binoviewer Complete Package

WO-E-BINO-P
7 in stock

Includes two 20mm 66° wide-angle eyepieces High-quality BaK4 prisms with full multi-coatings Large 20mm clear prism aperture prevents vignetting I...

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CA$509.00 - CA$509.00
CA$509.00
CA$509.00 - CA$509.00
CA$509.00
CA$1,087.00 - CA$1,087.00
CA$1,087.00
CA$1,087.00 - CA$1,087.00
CA$1,087.00

William Optics Flattener 68III

WO-P-FLAT68III

1.0x Flattener Power preserves native focal length Corrects field curvature for Full Frame sensors Designed for William Optics FLT132, GT102, and ...

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CA$1,087.00 - CA$1,087.00
CA$1,087.00
CA$1,087.00 - CA$1,087.00
CA$1,087.00
William Optics M48 Filter Adapters for Cat Eyes Binoculars
CA$12.00 - CA$12.00
CA$12.00
CA$12.00 - CA$12.00
CA$12.00

William Optics M48 Filter Adapters for Cat Eyes Binoculars

WO-AD-2X42-M48

Enables use of standard 2-inch (M48 x 0.75) filters Connects to the M44.5 x 0.75 objective threads on Cat Eyes Binoculars Adds a minimal 6 mm of o...

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CA$12.00 - CA$12.00
CA$12.00
CA$12.00 - CA$12.00
CA$12.00
CA$219.00 - CA$219.00
CA$219.00
CA$219.00 - CA$219.00
CA$219.00

William Optics RedCat WIFD Erecting Prism - 1.25"

WO-D-EP90-125-RC51III
1 in stock

Converts Astronomical Telescopes for Terrestrial Viewing 90-Degree Viewing Angle Accepts Standard 1.25" Eyepieces Anti-Reflection Coated BAK7 Pris...

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CA$219.00 - CA$219.00
CA$219.00
CA$219.00 - CA$219.00
CA$219.00
CA$156.00 - CA$156.00
CA$156.00
CA$156.00 - CA$156.00
CA$156.00

William Optics SPL 55° 12.5mm Eyepiece - 1.25"

WO-E-SPL12.5

1.25-inch eyepiece with 55° apparent field of view 12.5mm focal length for medium-high magnification viewing Description The W...

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CA$156.00 - CA$156.00
CA$156.00
CA$156.00 - CA$156.00
CA$156.00

Choosing Optical Accessories That Match Your Telescope

Every accessory in this collection modifies the light cone before it reaches your eye or sensor. The right choice depends almost entirely on your telescope's focal ratio, focal length and back-focus budget.

  • Eyepieces: Focal length sets magnification against your telescope's focal length; apparent field and eye relief determine how comfortable that magnification is to use.
  • Diagonals: Dielectric mirrors typically exceed 99% reflectivity; prisms can outperform them at f/10 and slower on planetary targets but introduce chromatic effects in fast refractors.
  • Barlow lenses and extenders: Multiply focal length for planetary work and push the focal plane outward, which is often the cheapest fix for a scope that will not reach focus with a diagonal.
  • Field flatteners and reducers: Correct field curvature and coma across large sensors; each has a fixed back-focus that must be hit precisely.
  • Binoviewers: Two-eye viewing that dramatically improves perceived detail on the Moon and planets, at the cost of significant added optical path.
  • Finders and reflex sights: Acquisition optics — the accessory most often skipped and most often missed.

Why Choose David Astro for Optical Accessories

Optics are easy to buy badly. A well-reviewed eyepiece can still be the wrong eyepiece for your focal ratio, exit pupil or sky.

  • Focal length guidance: We help you build a spaced eyepiece set rather than three focal lengths that overlap, and we calculate exit pupil against your aperture and typical seeing.
  • Corrector matching: We confirm that a flattener or reducer is designed for your telescope's focal ratio before you buy, since a mismatched corrector degrades a field rather than fixing it.
  • Authorized dealer: Full manufacturer warranty and verified authenticity on everything we list.
  • Canadian stock: In-stock optics ship from Canada, with no surprise duties or brokerage fees for Canadian customers.
  • Service and support after the sale: In-house diagnostics if something is not performing as expected.

Optical Accessories in Canada — Frequently Asked Questions

Will a premium eyepiece improve a modest telescope?
Usually yes at the edges of the field, especially in fast telescopes below f/6 where simpler designs struggle. On the axis at f/10, the difference between a good eyepiece and a premium one is much smaller.
How do I know if I need a flattener or a reducer?
A flattener corrects curvature at the same focal length. A reducer also shortens focal length, widening the field and speeding the system. If your stars are elongated only in the corners, you need a flattener; if you also want more field, a reducer.
Do binoviewers work in every telescope?
They add roughly 100 mm or more of optical path, so most refractors need a corrector or a Barlow-style element to reach focus. Schmidt-Cassegrains generally accommodate them without modification.
Is everything shipped domestically?
Yes. Anything shown as in stock is held in Canada and ships without customs delays for Canadian orders.

Match the accessory to the optic

Tell us your telescope and what you want to see, and we will recommend the right combination. Ships from Canada.