Trying to pick the perfect camera for your microscope can seem like a daunting task, especially when there are so many great options on the market! So, what factors should you consider while you're browsing? The most important thing to consider is the application you plan to use the camera. Below, we break down the main components that comprise a high-quality image: resolution, sensor type, frame rate, dynamic range, field of view, and color reproduction. You can use this knowledge to help you pick out the perfect camera for your needs!
Resolution: The resolution of a camera is usually defined as the size of the image that the camera produces, measured by the number of megapixels in one inch of the image. In general, a higher resolution means a larger, clearer, and more detailed picture, but in the world of microscopy, a higher number of pixels doesn't always mean a higher resolution. To get the best resolution for your microscope camera, you need to consider the:
- Microscope's total magnification
- Spatial frequency of tvhe sample
- Numerical aperture
- Pixel pitch
It can be tricky to achieve great resolution, but it's possible as long as you choose the camera with the proper pixel pitch in connection to the numerical aperture (NA), the total magnification of the microscope's optical system, and the sample's spatial frequency. You also need to think about why you need the camera and how you will be using it. If you plan on using it in an industrial setting, for example, you should go for a higher sampling pitch, since the samples you'll study in an industrial setting have sharp edges and higher spatial frequencies.
Sensor type: A microscope camera usually has one of two sensor types: CCD or CMOS.
- CCD (charged coupled device): The sensor in this camera has a 2D grid of pixels. During the image capture, the charge builds up in each pixel, and then the image is read following a signal output sequence in order to form a picture.
- CMOS (complementary metal-oxide semiconductor): The complementary metal-oxide semiconductor sensors are also referred to as active-pixel sensors. They're more complicated than the sensors in CCD cameras: each pixel has tiny semiconductor devices that amplify the electrical signal generated due to the traveling photons. Since CMOS cameras are faster than CCD cameras, they're often used in research-based settings, where a higher dynamic range and faster video frame rates are needed.
Frame rate: During live image viewing, fast frame rates are necessary for smooth operation. Many modern cameras have frame rates higher than 30 frames per second (fps), but many applications require even HIGHER frame rates. Some of these applications include (1) pathology consultation, (2) imaging of biological phenomena, (3) light-sheet fluorescence microscopy, and (4) computational imaging.
Dynamic range: In photography, the dynamic range of an image is the range of light intensities, from the image's shadows to its highlights. A greater dynamic range means the camera will be able to better display subtle color changes within the image. In other words, if there is a large range, it is easier to discriminate subtle differences in the light coming from different areas of the specimen.
Field of view (FOV): Some cameras provide a FOV over an 18 mm diagonal range. Other cameras, with smaller sensors, achieve a wide FOV by using camera adapters; however, doing so could mess with shading and optical aberration, especially when you go over 18 mm diagonally or perform image stitching.
Color reproduction: Because human eyes respond differently to colors than camera sensors, the camera needs to use multiple techniques in order to reproduce similar colors. Some of the features to keep an eye out for include:
White Balance: You want a microscope camera with proper white balance, which means that the camera detects and automatically fixes the bright background, which saves you from tedious adjustments. - Multi-Axis Color Adjustment: This feature allows the camera to highlight colors for different stains. For example, it can accurately distinguish between red and brown stains to show them individually in the image. - Color Spacing and Matching: These features allow the camera to show a wide range of colors, which is especially vital for intense greens, like the Masson's trichrome stain.
As important as each of these elements are, none of them are completely independent of each other; they are deeply correlated, especially resolution, frame rate, and field of view. For example, when observing a sample, you'll probably notice that a smaller pixel pitch gives higher resolution but less sensitivity. On the other hand, a camera adapter with a lower magnification provides less resolution but a higher sensitivity and a wider field of view. Think of what you need most from the images you'll take with your microscope camera in order to make the best decision. We hope this article has been informative and helpful as you try to decide which microscope camera you need!