![]() This equation assumes the imaging system is aberration-free. The lateral resolution (d) of an imaging system is calculated by the Abbe equation: d=0.61?/NA where d is the lowest resolvable distance, ? is the wavelength of the light used to image and NA the numerical aperture of the lens. It is, therefore, critical to determine the correct pixel size of the camera. If the pixels are too small for the sample size, it results in oversampling creating unnecessarily large files and loss of light in the image. This causes loss of resolution and artifacts (aliasing) in the final image. If the camera has pixels that are too large for the imaging system, it results in undersampling. If you want to take advantage of the maximum possible resolution of a microscope when imaging, you should match the resolution of the camera to that of the microscope. Schematic representation of a color camera with Bayer filter. If the microscope has only one camera port, you must come up with a viable plan to swap the cameras on the microscope based on the users’ needs.įigure 1. Before you do that, however, make sure your microscope has two available camera ports. With this in mind, it is safe to say that if you are planning to image histology samples as well as fluorescent samples, it is worth buying both a color and a monochrome camera. Based on this, a color camera does not work well for dimmer samples, and does not deliver high quality fluorescent imaging even for bright samples. For example, if a pixel lies between two red pixels, and the red has been blocked, the value for red light is interpolated and assigned to that pixel. The camera generates the colored image by interpolating the values for the pixels that contain no light information. In the case of green, however, two pixels out of four collect green light. With this filter, only one in four pixels detect red light while the other three pixels in a quadrant block all red light. Most color cameras use a filter, known as a Bayer filter, which is put over the camera’s detector (Figure 1). Why Color Cameras Are Not a Suitable Choice for Fluorescent Imaging This makes imaging low light samples difficult, if not impossible. However it reduces the overall amount of collected light. This is not entirely untrue: a color camera can acquire images of fluorescent samples. What if, however, you need to use your microscope for both fluorescent and bright field imaging? Colleagues or camera vendors will probably suggest a color camera, using the argument that a color camera might not be optimal for fluorescence, but it will get the job done. If you image only histology or only fluorescent samples, the choice is pretty straightforward. The rule of thumb? Use a monochrome camera for fluorescently-labeled samples and a color camera for bright-field imaging such as hematoxyline/eosin stained samples. The single most important factor in choosing between a color or monochrome camera is the sample preparation. We will also help you calculate the pixel size your new camera should have to match your microscope. In this first part, we will help you decide between a color or monochrome camera. In this two-part article we point out the main considerations to take into account when buying a new camera. For example, you may have to choose between camera sensitivity and speed of capture. Also, this is the time to make peace with the fact that you might have to make compromises between different aspects of the camera’s performance to accommodate your experiment. ![]() Things like sample brightness or the speed of the phenomenon you are trying to capture can dictate your choices. Before you set out to buy that camera, carefully consider your applications. Purchasing a microscope camera is one of the most daunting tasks you might have to undertake. ![]()
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