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Telescope Magnification Formula:
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Telescope magnification (also called power) is the factor by which a telescope enlarges the apparent size of distant objects. It is calculated by dividing the focal length of the objective lens or mirror by the focal length of the eyepiece.
The calculator uses the magnification formula:
Where:
Explanation: The formula shows that magnification increases with longer objective focal lengths and shorter eyepiece focal lengths.
Details: Calculating the correct magnification is essential for optimal viewing experience. Too high magnification can result in dim, blurry images, while appropriate magnification provides clear, detailed views of celestial objects.
Tips: Enter both objective and eyepiece focal lengths in millimeters. Both values must be positive numbers greater than zero for accurate calculation.
Q1: What is a typical magnification range for telescopes?
A: Most telescopes perform best at 20-50x per inch of aperture. Very high magnifications (over 300x) are rarely useful due to atmospheric limitations.
Q2: Can I use any eyepiece with my telescope?
A: Eyepieces must have the correct barrel size (1.25" or 2") to fit your telescope's focuser. The magnification calculation works regardless of barrel size.
Q3: Why does image quality decrease at high magnifications?
A: High magnification spreads the same amount of light over a larger area, making the image dimmer. Atmospheric turbulence and optical limitations also become more apparent.
Q4: What is the maximum useful magnification?
A: A general rule is 50x per inch of aperture (2x per mm). For example, a 100mm telescope has a maximum useful magnification of about 200x.
Q5: How does magnification affect field of view?
A: Higher magnification results in a narrower field of view, making it harder to locate objects but providing more detail on those you can find.