Réfracteurs
Refractors earn their following through consistency. A sealed lens system holds collimation indefinitely, cools quickly, gives high-contrast views without a central obstruction, and — in modern apochromatic form — produces the clean, round stars that make wide-field astrophotography look effortless. David Astro carries refractors in Canada, from compact 50 mm travel astrographs to large apochromatic triplets, shipping from Canadian stock.
We image with refractors under Canadian skies and can speak to the practical differences between doublets and triplets, and between glass types, in terms of what actually shows in a finished image rather than what appears on a specification sheet.
Filtres
SVBONY SV502 Astronomy Telescope for Kids
50mm Refractor Telescope 360mm Focal Length (f/7.2) Includes K20mm Eyepiece 5x20 Optical Viewfinder 45-Degree Correct-Image Prism for Upright View...
Afficher tous les détailsSVBONY SV503 102mm f/7 ED Doublet Refractor Telescope OTA
102mm Aperture ED Doublet Refractor 714mm Focal Length (f/7) S-FPL51 Extra-Low Dispersion Glass 1:10 Dual-Speed Rack & Pinion Focuser 101.9mm ...
Afficher tous les détailsSVBONY SV503 70mm f/6.78 Quadruplet ED Flatfield Refractor Telescope OTA
70mm Aperture Quadruplet Astrograph 474mm Focal Length (f/6.78) 32mm Corrected Flat-Field Image Circle 2.5" Rack-and-Pinion Focuser 127.5mm Workin...
Afficher tous les détailsSVBONY SV503 ED 80mm F7 Doublet
1.Rugged housing prevents damage; 2.Sliding graceful and soft dual-speed focuser; 3.Ed glass (S-FPL51) can produce very beautiful and clear images...
Afficher tous les détailsSVBONY SV520 Astronomy Telescope Complete Kit for Beginners
90mm Objective Aperture f/8.9 Focal Ratio Alt-Azimuth Mount with Worm Gear Slow-Motion Controls Includes 3X Barlow Lens 5x24 Optical Finder Scope ...
Afficher tous les détailsSVBONY SV545 45mm f/4.5 203mm Petzval Refractor Astrograph Lens
45mm Aperture 203mm Focal Length (f/4.5) 5-Element Petzval Optical Design Native Flat-Field Astrograph Helical Focuser with 360º Rotator M48x0.75 ...
Afficher tous les détailsSVBONY SV550 122mm APO Refractor Telescope OTA
Ouverture de 122mm Rapport focal f/7 Focale de 854mm Objectif triplet apochromatique avec verre ED FPL-51 Optique à traitement Super Multi-Coated ...
Afficher tous les détailsSVBONY SV550 80mm f/6 APO Triplet Refractor Telescope OTA
80mm Aperture Apochromatic Triplet Refractor 480mm Focal Length Fast f/6 Focal Ratio FPL51 ED Glass Element for Color Correction Resolving Power o...
Afficher tous les détailsSVBONY SV555 54mm f/4.5 Petzval APO Astrograph Lens
54mm Aperture / 243mm Focal Length (f/4.5) 5-Element Petzval APO Optical Design 44mm Full-Frame Image Circle Variable f/4.5 to f/22 Aperture Ring ...
Afficher tous les détailsTele Vue TV-60 OTA
Aperture: 60mm Focal Length: 360mm Focal Ratio: f/6 Optical Design: APO Doublet (2 elements / 1 group) Focuser: 1.25" Helical Weight: 3 lbs (OTA) ...
Afficher tous les détailsTele Vue TV-76 OTA - Green
Aperture: 76mm Focal Length: 480mm Focal Ratio: f/6.3 Optical Design: APO Doublet (2 elements / 1 group) Focuser: 2-inch Focusmate Dual-Speed Rack...
Afficher tous les détailsTele Vue TV-76 OTA - White
Aperture: 76mm Focal Length: 480mm Focal Ratio: f/6.3 Optical Design: APO Doublet (2 elements / 1 group) Focuser: 2-inch Focusmate Dual-Speed Rack...
Afficher tous les détailsTele Vue TV-85 OTA - Green
Aperture: 85mm Focal Length: 600mm Focal Ratio: f/7 Optical Design: APO Doublet (2 elements / 1 group) Focuser: 2-inch Focusmate Dual-Speed Rack a...
Afficher tous les détailsTele Vue TV-85 OTA - White
Aperture: 85mm Focal Length: 600mm Focal Ratio: f/7 Optical Design: Apochromatic (APO) Doublet Focuser: 2-inch, 10:1 Dual-Speed Rack-and-Pinion We...
Afficher tous les détailsTele Vue TV-NP101is OTA
Aperture: 101mm Focal Length: 540mm Focal Ratio: f/5.4 Optical Design: APO Nagler-Petzval (4 elements / 2 groups) Focuser: 2.4" Focusmate Dual-Spe...
Afficher tous les détailsTele Vue TV-NP127is OTA
Aperture: 127mm Focal Length: 660mm Focal Ratio: f/5.2 Optical Design: APO Nagler-Petzval (4 elements / 2 groups) Focuser: 2.4" Focusmate Dual-Spe...
Afficher tous les détailsWilliam Optics Cat 91 WIFD
Lunette portable Petzval APO 51 mm f/4,9 Idéal pour l'astrophotographie du ciel profond à grand champ Cercle d'imagerie à champ plat plein f...
Afficher tous les détailsWilliam Optics Fluorostar 120
120 mm APO Rapport focal rapide F/6 Portable et polyvalent Description Caractéristiques Dans la boite Libérez votre passio...
Afficher tous les détailsWilliam Optics Fluorostar 132
APO de 132 mm Rapport focale rapide F/6.9 Portable et polyvalent Description Caractéristiques Dans la boite Libérez vot...
Afficher tous les détailsWilliam Optics Fluorostar 156
APO de 156 mm Rapport focale rapide F/6,7 Portable et polyvalent Description Caractéristiques Dans la boite Libérez vot...
Afficher tous les détailsWilliam Optics Fluorostar 91
APO de 91 mm utilisant du verre FPL-53 Rapport focale rapide F/5.9 Portable et polyvalent Description Caractéristiques Dans la b...
Afficher tous les détailsWilliam Optics Gran Turismo 71 Triplet APO
Triplet APO de 71 mm Rapport focale rapide F/5.9 Portable et polyvalent Description Caractéristiques Dans la boite Libé...
Afficher tous les détailsWilliam Optics Gran Turismo WIFD 81
APO de 81 mm Rapport focale rapide F/5.9 Portable et polyvalent Description Caractéristiques Dans la boite Libérez votr...
Afficher tous les détailsWilliam Optics MiniCat 51 WIFD f/3.5
51mm Aperture Diameter 178mm Focal Length f/3.5 Focal Ratio 6-Element Petzval Optical Design 43.2mm Full-Frame Image Circle WIFD Rack & Pinion...
Afficher tous les détailsDoublets, Triplets and Glass Types
The purpose of an apochromatic design is to bring three wavelengths to a common focus, eliminating the violet halo that achromatic refractors show on bright stars. How well it does that depends on the glass and the number of elements.
- ED doublets: Two elements with one extra-low dispersion element. Lighter, less expensive, and excellent for imaging, with a small residual colour that is rarely visible in processed images.
- Apochromatic triplets: Three elements giving near-complete colour correction, preferred for high-contrast visual observing and for imaging bright stars without halos. Heavier and slower to cool.
- Petzval designs: Four-element optics with the field correction built in, so no separate flattener is needed and back-focus is fixed by the manufacturer — the simplest path to flat fields.
- Achromatic refractors: Two-element crown and flint designs, excellent value for lunar, planetary and general visual use where some colour fringing on bright objects is acceptable.
- Focal ratio: Fast refractors around f/5 give wide fields and short exposures; f/7 and slower give more image scale and are more forgiving of corrector spacing.
- Matched correctors: Most refractors need a flattener or reducer designed for that specific model, spaced to its exact back-focus.
Why Choose David Astro for Refractors
A refractor is usually bought as the centre of an imaging system, so it should be specified alongside the mount and camera rather than on its own.
- Corrector matched at the point of sale: We identify the flattener or reducer designed for your specific tube and supply the spacers to hit its back-focus exactly.
- Focuser load assessed: We check that the stock focuser will carry your intended camera train without slip, and recommend an upgrade only when it genuinely will not.
- Authorized dealer: Full manufacturer warranty and verified authenticity, with service handled inside Canada.
- Ships from Canadian stock: No duties or brokerage fees for Canadian buyers, and no extra border handling for a precision optic.
- Support after first light: Help with spacing, tilt and star shape diagnosis once the telescope is on the sky.
Refractors in Canada — Frequently Asked Questions
- Doublet or triplet for imaging?
- A good ED doublet is entirely sufficient for most deep-sky imaging and is lighter on the mount. A triplet shows its advantage on bright stars and in high-contrast visual use, at meaningful extra weight and cost.
- Do I need a field flattener?
- For imaging with anything larger than a small sensor, yes — a two-element refractor has a curved focal plane and corners will show elongated stars without one. Petzval designs have it built in.
- How long does a refractor take to cool?
- A small doublet is usable almost immediately. A large triplet can take 45 minutes or more to stabilize in Canadian winter conditions, and imaging before it does will show soft, bloated stars.
- Is a small refractor enough for deep sky?
- Yes, given integration time. A 60 to 80 mm apochromat on a good mount produces excellent wide-field images; total exposure time substitutes for aperture in imaging in a way it cannot for visual work.
Specifying a refractor?
Tell us your mount, camera and targets and we will match the tube and its corrector. Canadian stock, no surprise duties.