Magnifying Power of Astronomical Telescope (m = -f_o/f_e (normal adjustment))
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m = -f_o/f_e (normal adjustment)
What each symbol means
| Symbol | What it stands for |
|---|---|
| m | Angular magnification (magnitude gives magnifying power) |
| f_e | Focal length of the eyepiece lens |
| f_o | Focal length of the objective lens |
When to use this
Normal adjustment (relaxed eye, final image at infinity). Tube length L = f_o + f_e. Negative sign indicates inverted image. For image at near point: m = -(f_o/f_e)(1 + f_e/D) where D = 25 cm.