What is the MTF?

Modulation Transfer Function (MTF)

The Modulation Transfer Function (MTF) is a critical measure in optical engineering that quantifies the ability of an optical system to transfer various levels of detail from the object to the image. It is a comprehensive indicator of system performance, encompassing factors such as resolution, contrast, and the presence of aberrations.

Understanding MTF

MTF is represented as a curve that plots the contrast or modulation of the image against the spatial frequency (details per unit distance) of the object. The spatial frequency is measured in cycles or line pairs per millimeter (lp/mm), indicating how many pairs of lines (one black and one white) can be distinguished per millimeter.

Key Components

  • Resolution: The maximum spatial frequency at which the system can reproduce detail. Higher resolutions correspond to higher spatial frequencies.
  • Contrast: The ability of the optical system to differentiate between light and dark areas. A system with high contrast can distinguish fine details better.
  • Aberrations: Imperfections in the optical system that can degrade image quality. The MTF curve can indicate the presence and severity of aberrations.

Significance of MTF

MTF provides a more comprehensive understanding of an optical system's performance than simple resolution tests. It takes into account how different spatial frequencies are transferred from the object to the image, offering insights into the practical limits of the system's performance. By analyzing the MTF curve, engineers can optimize optical designs, ensuring high-quality imaging across a range of conditions.


MTF is widely used in various fields, including photography, microscopy, and telescope design, to evaluate and compare the performance of optical systems. It is a fundamental tool in optical engineering for designing, testing, and improving lenses, cameras, and other imaging devices.

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