A camera with a large sensor, on the other hand, will see the whole field determined only by the microscope objective.Īn aphis viewed through the same 10× plan achromat lens and different 10× eyepieces with FN = 16.7 and FN = 20 note the same size of the aphis image and different field sizes due to different eyepiecesĪs was mentioned above, the field diameter usually depends on the magnification of the microscope objective and the field diaphragm of the eyepiece. When using a camera with a small sensor, it is common to use a reduction lens, which is installed on the camera. If an eyepiece is substituted with a camera, especially if the camera is installed instead of the binocular head, then the field of view will be determined by the size of the camera image sensor (for cameras with relatively small sensors) and/or the microscope objective. This calibration must be performed for every eyepiece and objective lens combination. To get the actual field of view of your particular microscope with a particular objective and eyepiece lenses, your microscope needs to be calibrated using a calibration slide. Note that this calculation is only an estimate.

For example, 10×/18 and 12×/18 eyepieces have the same eyepiece field of view diameter FN = 18 mm. In most cases, the field diaphragm opening diameter (called field number of FN) of the eyepiece determines the view field diameter.ġ mm (1 division = 0.01 mm) and 50 mm (1 division = 0.5 mm) calibration slidesĪs you can see from the above formula, the ocular magnification does not have any effect on the field of view. The field of view is defined by a fixed (because it cannot be changed) circular opening (diaphragm) of the eyepiece, which, depending on its design, can be either between the eyepiece lenses or below them. The eyepiece field number (abbreviated as FN and sometimes as FOV) is the diameter of the field view in millimeters measured at the intermediate real image plane. If a full-frame DSLR camera is used for taking pictures and videos, its sensor size is usually larger than the other limiting factors.Īny microscope eyepiece is characterized at with least two numbers: its magnification (10× being the most common) and the field number. The microscope field of view is limited by the objective lens, the diameter of the internal mechanical optical path (tube), the eyepieces used and the camera sensor size. The microscope field of view is the maximum diameter of the area visible when looking through the eyepiece (that will be the eyepiece field of view) or using a camera (that will be the camera field of view). Calculation of the Microscope Field of View The eyeglasses sign on the left eyepiece shows that it is designed as a high point or eye relief eyepiece and can be used by people wearing eyeglasses. The field number is not engraved on the left eyepiece it was determined by means of measuring the internal diaphragm diameter.

Wide-field 10× eyepieces with field numbers 20 mm and 16 mm.

Microscope resolution calculator