Telescope Nerd » Sizes » 3-inch Telescopes (76-94mm)

3-inch Telescopes (76-94mm)

3-inch telescopes are ideal for kids and beginner astronomers. On average, they provide 300-900 mm focal lengths and a range of focal ratios from  f/3.9-f/12. They can magnify objects 152-189x times the human eye. You can get 3-inch telescopes from different brands in the price range of 262-5200$.

What is a 3-inch telescope?

A 3-inch telescope has an aperture (the diameter of the objective lens) of 3-3.75 inch (76-94 mm). 3-inch telescopes are in the category of small-size telescopes.

What can you see with a 3-inch telescope?

  • Venus and its phases
  • The Moon with craters.
  • Jupiter’s cloud· bands, and the Great Red Spot
  • Saturn with rings.
  • M 31 and M 33
  • NGC galaxies  
  • Nebulae like M 42, M 8, etc.

Types and Technical Specifications of 3-inch telescope

Types (Optical Design)

Dobsonian: Example: Orion FunScope 76mm Tabletop Dobsonian f/3.9 Telescope Kids Kit

Newtonian: Example: Celestron AstroMaster LT 76AZ Telescope, Celestron FirstScope Telescope, Celestron Cometron FirstScope 76 Telescope, Celestron FirstScope Signature Series Moon by Robert Reeves, Celestron National Park Foundation FirstScope f/3.9 Newtonian Reflecting Telescope, Orion SpaceProbe II 76mm f/9.2 Newtonian Reflecting Telescope

Maksutov Cassegrain: Example: Orion FunScope 76mm Tabletop Dobsonian Reflector Telescope, Sky-Watcher Virtuoso Versatile Alt-Azimuth Mount

Doublet Refractor: Example: Explore Scientific Firstlight AR90mm White Tube Refractor W/ AZ Mount, Celestron AstroMaster 80AZ Refractor Telescope, Celestron Astro Fi 90 mm WiFi Refractor, Sky-Watcher Evolux 82ED Doublet APO Refractor, Celestron StarSense Explorer LT 80AZ Smartphone Telescope, Celestron PowerSeeker 80AZS Telescope, Takahashi Starbase 80 f/10 Doublet Refracting Telescope, Explore Scientific FirstLight 80mm Refractor with Twilight Nano Mount, Explore Scientific FirstLight 80 mm GoTo Refractor Package, iOptron 80mm Refractor, William Optics Super ZenithStar 81 Doublet Refractor Telescope – Astrophotography Package – Red & Gold, Celestron 80LCM Computerized Telescope, Vaonis STELLINA Smart Telescope, Orion ST80-A Refractor Astro Version w No Case, Orion ST80-T Refractor Terrestrial Version w No Case, Orion ST80 Refractor OTA, Orion CT80 Compact f/5 Doublet Refracting OTA Telescope

Triplet Refractor: Example: Sharpstar 94mm f/5.5 ED Triplet Apo Refractor Telescope, William Optics Gran Turismo 81 APO Triplet Refractor Telescope – Gold, Gray, Red, Orion Grab-n-Go 80mm f/6 Triplet Refracting Telescope

Technical Specifications

Aperture: 3-3.75 inch (76-94 mm)

Focal Length: 300-900 mm 

Focal ratio: f/3.9-f/12

Highest Magnification: 152-189x

Light Gathering Power: 118-131x

Price: 69-1,495$

Images taken with 3-inch telescopes

Examples of 3-inch telescopes

3-inch

  • Orion FunScope 76mm Tabletop Dobsonian Reflector Telescope
  • Celestron AstroMaster LT 76AZ Telescope
  • Celestron FirstScope Telescope
  • Celestron Cometron FirstScope 76 Telescope
  • Orion FunScope 76mm Tabletop Dobsonian f/3.9 Telescope Kids Kit
  • Celestron FirstScope Signature Series Moon by Robert Reeves
  • Celestron National Park Foundation FirstScope f/3.9 Newtonian Reflecting Telescope
  • Orion SpaceProbe II 76mm f/9.2 Newtonian Reflecting Telescope

3.25-inch 

  • Orion Grab-n-Go 80mm f/6 Triplet Refracting Telescope
  • Orion ST80 Refractor OTA
  • Orion CT80 Compact f/5 Doublet Refracting OTA Telescope
  • Celestron Travel Scope 80 Portable Telescope with Backpack
  • Celestron AstroMaster 80AZ Refractor Telescope
  • Sky-Watcher Evolux 82ED Doublet APO Refractor
  • Celestron StarSense Explorer LT 80AZ Smartphone Telescope
  • Orion ST80-T Refractor Terrestrial Version w No Case
  • Orion ED80T Carbon Fiber ED APO Refractor Telescope
  • Takahashi Starbase 80 f/10 Doublet Refracting Telescope
  • Explore Scientific FirstLight 80mm Refractor with Twilight Nano Mount
  • Explore Scientific FirstLight 80 mm GoTo Refractor Package
  • iOptron 80mm Refractor
  • William Optics Super ZenithStar 81 Doublet Refractor Telescope – Astrophotography Package – Red
  • Celestron 80LCM Computerized Telescope
  • Celestron PowerSeeker 80AZS Telescope
  • William Optics Gran Turismo 81 APO Triplet Refractor Telescope – Gold, Gray, Red
  • Vaonis STELLINA Smart Telescope
  • Orion ST80-A Refractor Astro Version w No Case

3.5-inch

  • Explore Scientific Firstlight AR90mm White Tube Refractor W/ AZ Mount
  • Celestron Astro Fi 90 mm WiFi Refractor
  • Sky-Watcher Virtuoso Versatile Alt-Azimuth Mount

3.75 inch

  • Sharpstar 94mm f/5.5 ED Triplet Apo Refractor Telescope

How do 3-inch telescopes compare to other size-telescopes

3-inch vs 4-inch telescopes

3-inch telescopes provide focal lengths of 300-900 mm ( f/3.9-f/12), while 4-inch telescopes vary in focal lengths from 450-1350 mm (f/3.9-f/9). 3-inch telescopes provide the highest magnification of 152-189x, whereas 4-inch telescopes can magnify 204-236x. 

3-inch telescope4-inch telescope
Aperture3-3.75 inch (76-94 mm)4-4.75 inch (100-120 mm)
Focal Ratiof/3.9-f/12f/3.9-f/9
Focal Length300-900 mm450-1350 mm
Highest Magnification152-189x204-236x
Price69-1,495$262-5,200$

3-inch vs 5-inch telescope

5-inch telescopes provide a focal length of 650-1900 mm with a focal ratio of f/5-f/15. In contrast, 3-inch telescopes vary from 450-1350 mm in focal length with a focal ratio of f/3.9-f/9. Moreover, 5-inch telescopes provide 225-260x the highest magnification, which is 152-189x in the case of 3-inch telescopes.

3-inch telescope5-inch telescope
Aperture3-3.75 inch (76-94 mm)5-inch (127-130 mm)
Focal Ratiof/3.9-f/12f/5-f/15
Focal Length300-900 mm650-1900 mm
Highest Magnification152-189x225-260x
Price69-1,495$279-8,400$

3-inch vs 6-inch telescopes

3-inch telescopes have less aperture than the 6-inch telescopes. They offer a focal ratio of f/3.9-f/10 whereas the 3-inch telescopes vary from f/3.9-f/12. However, 6-inch telescopes offer a focal length of 162-1800 mm. On the other hand, 3-inch telescopes vary from 300-900 mm in focal lengths. 6-inch telescopes provide the highest magnification of 295-320x, whereas 3-inch telescopes can magnify 152-189x. 

3-inch telescope6-inch telescope
Aperture3-3.75 inch (76-94 mm)6-inch (150 mm)
Focal Ratiof/3.9-f/12f/3.9-f/10
Focal Length300-900 mm162-1800 mm
Highest Magnification152-189x295-320x
Price69-1,495$310-15,070$

3-inch vs 7-inch telescopes

3-inch telescope has less aperture than the 7-inch telescopes. They offer a focal ratio of f/2.8-f/15 whereas the 3-inch telescopes vary from  f/3.9-f/12. Besides, 3-inch telescopes offer a focal length of 300-900 mm whereas the 7-inch telescopes start from 500 mm to 2700 mm mm in focal lengths. Moreover, 7-inch telescopes provide 360x the highest magnification, whereas 3-inch telescopes can magnify up to 152-189x.

3-inch telescope7-inch telescopes
Aperture3-3.75 inch (76-94 mm)7-inch (180 mm)
Focal Ratiof/3.9-f/12f/2.8-f/15
Focal Length300-900 mm500-2700 mm
Highest Magnification152-189x360x
Price69-1,495$1,350-5,500$

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