Free astronomy tool
Dobsonian Telescope Design Calculator
Enter your mirror size and focal ratio to check the tube layout, secondary mirror size, and a draft parts list.
- Set your mirror size
- Adjust the focuser and light path
- Review the layout and parts
Optical Parameters
8" / 203mm @ f/6.0Calculated Engineering Specs
Live Optical Cross-Section & Ray-Trace Schematic
Recommended Parts & Sourcing Kit
Component categories matched to your 8-inch plan. Exact seller links are withheld until the listing and fit are individually verified.
6-Inch primary mirror
A generic parabolic primary-mirror size used in some Newtonian telescope projects.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Do not buy from a search result until the seller supplies exact dimensions, substrate, coating details, return policy, and an optical test report for that unit.
8-Inch primary mirror
A generic parabolic primary-mirror size used in some Newtonian telescope projects.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Do not buy from a search result until the seller supplies exact dimensions, substrate, coating details, return policy, and an optical test report for that unit.
10-Inch primary mirror
A generic parabolic primary-mirror size used in some Newtonian telescope projects.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Do not buy from a search result until the seller supplies exact dimensions, substrate, coating details, return policy, and an optical test report for that unit.
12-Inch primary mirror
A generic parabolic primary-mirror size used in some Newtonian telescope projects.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Do not buy from a search result until the seller supplies exact dimensions, substrate, coating details, return policy, and an optical test report for that unit.
1.25-Inch secondary mirror
A generic elliptical secondary-mirror size for a Newtonian telescope design.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Calculate the required minor axis for your geometry and verify the seller documents surface flatness, coating, dimensions, and return terms.
1.83-Inch secondary mirror
A generic elliptical secondary-mirror size for a Newtonian telescope design.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Calculate the required minor axis for your geometry and verify the seller documents surface flatness, coating, dimensions, and return terms.
2.14-Inch secondary mirror
A generic elliptical secondary-mirror size for a Newtonian telescope design.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Calculate the required minor axis for your geometry and verify the seller documents surface flatness, coating, dimensions, and return terms.
2.60-Inch secondary mirror
A generic elliptical secondary-mirror size for a Newtonian telescope design.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Calculate the required minor axis for your geometry and verify the seller documents surface flatness, coating, dimensions, and return terms.
8" spider mount
A generic secondary holder and spider configuration for Newtonian telescopes.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Measure the inside tube diameter and secondary size, then verify the actual vane geometry, adjustment range, and mounting hardware.
Spider Mount
A generic secondary holder and spider configuration for Newtonian telescopes.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Measure the inside tube diameter and secondary size, then verify the actual vane geometry, adjustment range, and mounting hardware.
12 mirror cell
A generic primary-mirror support concept for a Dobsonian or Newtonian build.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Use a mirror-support calculator for the actual diameter, thickness, and glass type. Verify edge support and retention before construction.
10" mirror cell
A generic primary-mirror support concept for a Dobsonian or Newtonian build.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Use a mirror-support calculator for the actual diameter, thickness, and glass type. Verify edge support and retention before construction.
10 focuser
A generic telescope focuser style for a custom optical tube.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Measure racked-in height, travel, mounting-hole pattern, and expected accessory load before choosing a listing.
1.25-Inch focuser
A generic telescope focuser style for a custom optical tube.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Measure racked-in height, travel, mounting-hole pattern, and expected accessory load before choosing a listing.
6 bearings hardware
Generic bearing material or hardware that may be used in a Dobsonian mount.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Prototype the bearing system under the finished telescope weight; seller material claims and dimensions must be verified before purchase.
Bearings Hardware
Generic bearing material or hardware that may be used in a Dobsonian mount.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Prototype the bearing system under the finished telescope weight; seller material claims and dimensions must be verified before purchase.
8" bearings hardware
Generic bearing material or hardware that may be used in a Dobsonian mount.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Prototype the bearing system under the finished telescope weight; seller material claims and dimensions must be verified before purchase.
Tube Materials
Generic tube or light-control material for a telescope build.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Measure the actual tube and test adhesives or coatings on an offcut. Keep loose fibers and reflective surfaces away from the optics.
10" tube materials
Generic tube or light-control material for a telescope build.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Measure the actual tube and test adhesives or coatings on an offcut. Keep loose fibers and reflective surfaces away from the optics.
1.25" collimation testing
A generic optical alignment tool for compatible Newtonian telescopes.
Specs: Seller-specific dimensions, materials, coatings, tolerances, and included hardware are not verified. Confirm every measurement against your design.
Builder Tip: Follow a reputable collimation procedure and verify alignment with more than one method when possible.
Ready to Build Your Own Telescope?
Read our complete, illustrated step-by-step woodworking & optics guide covering mirror cells, spider alignment, Teflon-on-FRP smooth motion, and star collimation.