When an average person talks about lenses, what do you think is the first image that comes to their mind? They’d probably mention cameras in general – but the most common are the professional camera. However, there are several devices that make use of lenses aside from cameras such as microscopes, periscopes and much more. A lot of medical equipment make use of such component as well. Each of these lenses is designed for a specific purpose, but before they make it to the device that they are designated for, they go through an MTF test first. It is just like a quality control check to see whether or not it passes the standard test. Companies like the image-science.com conduct such tests.
The quality of the lenses is getting more significant these days. And one of the major reasons for this is the growing demand for the megapixels found in most of the digital cameras today. Even smartphones demand higher megapixel to accommodate the quality they are looking for in DSLR cameras, but too heavy to carry them around. The resolution of the digital photos is dependent on the lens quality of the camera, and not by the body of the camera itself. It is because of this that professional and amateur photographers are quite keen about the lens quality of the camera because it will affect the resolution of the photos they are taking. And to do that, they need to learn how to read MTF charts. The basics are shared below for you to know better in choosing a lens.
Most people are familiar with the image resolution concept. However, most information is focused too much on this particular metric. Resolution only focuses on how much detail the lens is capable of taking. It doesn’t necessarily focus on the detail quality being captured. The other factors contribute to the performance of the lens, thus is affects the perception of the sharpness and quality of the digital image.
Take for example when an object or image passes through the lens. There are a lot of explanations out there that can be very confusing for an average person to understand. There are diagrams online that show how the image is being translated through the lens. These images are presented in alternating lines of black and white, thus referred to as line pairs.
The MTF or Modulation Transfer Function quantities in how well the regional brightness variants of the subject are well preserved when they go through the lens. A perfect curve in the MTF test results reveals that it is the perfect lens to have. But always keep in mind that there is not a single lens that has gotten the perfect MTF score.
If you see an MTF figure of 1.0, it presents the perfect preservation of contrast, while the figures less than the mean above that more contrast is getting lost, until it reaches an MTF figure of 0. At this figure, the line pairs can no longer be distinguished.