• Pixel-art sticker of Scopie, personifying Telescope Magnification, with the caption “Long Over Short.”

IndexForces & FieldsSticker

Scopie

Telescope Magnification Physics

\[M = \frac{f_o}{f_e}\]
$4.99 USD
$4.99 USD
Sale Sold out

Meet Scopie, a brass telescope who makes the Moon look huge with two lenses. Magnification is the objective's focal length over the eyepiece's, so 900 mm with 25 mm gives 36 times, turning the half-degree Moon about 18° wide. Galileo managed about 20 times. Pixel-art kiss-cut sticker in 2, 3, 4 and 6 inches; equation, symbols and sources in the physics panel below.

Size
Surface

Flat $6 shipping worldwideMade to order, ships in 2–5 business days

Details

Size3″ × 3″

3″ × 3″ kiss-cut sticker.

Shipping

Flat $6 shipping on every order, worldwide, whatever's in it.

Delivery times & where we ship

Returns & replacements21 days

Every item is printed to order, so we can’t accept returns or exchanges for change of mind, or if you ordered the wrong size or colour.

Print defect, misprint, damage or the wrong item? We’ll send a free replacement, or a refund if you prefer. Report it within 21 days of delivery with a photo; no need to send it back.

Full refund & replacement policy

The physics

Meet Scopie, a brass telescope who makes the Moon look huge with two lenses.

A simple refracting telescope has a large objective lens at the front and a small eyepiece at the back. The objective gathers light from a distant object and forms a small image near its focal point. The eyepiece then acts like a magnifying glass, letting your eye look closely at that image.

The angular magnification is M = fₒ/fₑ, the focal length of the objective divided by that of the eyepiece. A 900 mm objective with a 25 mm eyepiece gives M = 36. The Moon, about 0.5° wide to the naked eye, then looks about 18° across.

Swap in a 10 mm eyepiece and M rises to 90. But the image also gets dimmer and blurrier, so the objective's size sets a useful limit.

Galileo's first telescopes in 1609 magnified only about 20 times, yet they showed him craters on the Moon and four moons circling Jupiter.

Equations

\[M = \frac{f_o}{f_e}\]
SymbolMeaningUnit
\(M\) angular magnification \(\mathrm{dimensionless}\)
\(f_o\) focal length of the objective lens \(\mathrm{m}\)
\(f_e\) focal length of the eyepiece \(\mathrm{m}\)

Sources

  1. OpenStax University Physics Vol. 3 — Microscopes and Telescopes
  2. Wikipedia — Refracting telescope

Field notes

View all
  • Pixel-art illustration for this Pixelated Physics post: a pixel pendulum bob character swinging over a circular floor marked with pixel pegs, a few pegs knocked over showing the swing plane slowly turning, a pixel Earth spinning in the window

    How Does a Foucault Pendulum Prove Earth Rotates?

    A long pendulum’s swing plane slowly turns relative to the floor. Foucault showed in 1851 that the turn is Earth’s rotation made visible. The rate is 360° times the sine...

    How Does a Foucault Pendulum Prove Earth Rotates?

    A long pendulum’s swing plane slowly turns relative to the floor. Foucault showed in 1851 that the turn is Earth’s rotation made visible. The rate is 360° times the sine...

  • Pixel-art Einstein ring: a foreground galaxy bends the light of a galaxy directly behind it into a circular ring of arcs centered on it

    How Does Gravity Bend Light? Einstein Rings and...

    Gravity bends light because spacetime is curved. The 1919 eclipse measured the Sun’s deflection; Einstein’s 1936 note foresaw stellar lenses; modern telescopes image Einstein rings. Here is the physics without...

    How Does Gravity Bend Light? Einstein Rings and...

    Gravity bends light because spacetime is curved. The 1919 eclipse measured the Sun’s deflection; Einstein’s 1936 note foresaw stellar lenses; modern telescopes image Einstein rings. Here is the physics without...

  • Pixel-art illustration for this Pixelated Physics post: three abstract pixel mascots of early quantum ideas: a glowing light-packet character, a tiny atom with stepped orbit rings, and a fuzzy uncertainty cloud, climbing a staircase of energy levels

    Who Started Quantum Mechanics? Planck, Bohr and...

    Quantum theory did not begin with one paper. Planck quantized energy in 1900, Bohr quantized the atom in 1913, and Heisenberg’s 1925 matrix mechanics plus the 1927 uncertainty relation made...

    Who Started Quantum Mechanics? Planck, Bohr and...

    Quantum theory did not begin with one paper. Planck quantized energy in 1900, Bohr quantized the atom in 1913, and Heisenberg’s 1925 matrix mechanics plus the 1927 uncertainty relation made...

1 3
View all