# Optical Magnification Calculator

M = 250/f for magnifiers, (L/f_o)·(250/f_e) factorized for microscopes, f_o/f_e for telescopes.

> Canonical page: https://elysiatools.com/en/tools/magnification-power

- **Category:** Science & Education

- **Keywords:** magnification, magnifying glass, microscope, telescope, focal length, optics

## Overview

The Optical Magnification Calculator computes the total magnifying power and component factorizations for magnifying glasses, compound microscopes, and telescopes based on standard optical formulas and focal lengths in millimeters.

## Inputs

- **Instrument** (select)
- **Magnifier focal length f (mm)** (number): e.g. 50
- **Objective focal length f_o (mm)** (number): e.g. 4
- **Eyepiece focal length f_e (mm)** (number): e.g. 25
- **Tube length L (mm)** (number): e.g. 160

## When to use

- Determining the angular magnification of a simple magnifying lens using the standard 250 mm reference near point.
- Calculating the combined magnification of a compound microscope from objective focal length, eyepiece focal length, and optical tube length.
- Finding the visual magnification of an astronomical telescope setup by comparing objective and eyepiece focal lengths.

## How it works

- Select your target optical system: magnifying glass, microscope, or telescope.
- Enter the relevant focal lengths and tube dimensions in millimeters.
- The tool applies standard optical equations (M = 250/f for magnifiers, M = (L/f_o)·(250/f_e) for microscopes, or M = f_o/f_e for telescopes) to output exact magnification and intermediate factor breakdowns.

## Use cases

- Optics students verifying laboratory calculations for focal length and visual magnification experiments.
- Microscopy technicians configuring objective and eyepiece combinations for target specimen scale.
- Amateur astronomers selecting appropriate eyepieces to achieve desired planetary or deep-sky magnification.

## Frequently asked questions

### What standard near point distance is used for magnifiers and microscopes?

The calculator uses the standard optical convention of 250 mm (25 cm) as the clear visual near point distance.

### How is telescope magnification calculated?

Telescope magnification is calculated directly as the ratio of objective focal length to eyepiece focal length (M = f_o / f_e).

### Can I input focal lengths in units other than millimeters?

All inputs require millimeter (mm) values to match the standard formula scales.

### What is the standard optical tube length for compound microscopes?

Standard biological microscopes traditionally use a mechanical tube length of 160 mm, which is provided as the default value.

### How does compound microscope magnification break down?

It is the product of the objective magnification (L / f_o) and the eyepiece magnification (250 / f_e).

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