Abstract This research aims to measure the focal distance of a lens using practical lens properties. The specifications of this practical tool are made from durable acrylic material, light and easy to use. The lens nature practice equipment consists of a light source in the form of an incandescent lamp, lens path, image capture screen, arrow diaphragm, power supply, strong positive lens (+100), weak positive lens (+50) and negative lens (-50). In this practical, the light source, object, lens and screen are placed parallel. Measurements are carried out through scientific process skills including observation, classification, measurement, prediction, communication and drawing conclusions which begin with observing the image produced by the lens using three different object-to-screen distances, namely 40 cm, 60 cm and 80 cm. In addition to determining the focal distance, experiments with positive lenses produce real, inverted and magnified images. Meanwhile, in a negative lens, the image is virtual and upright. In the positive strong lens experiment, the focal distances measured at distances L = 80 cm, 60 cm, and 40 cm respectively produced average focus values of 10.53 cm, 10.49 cm, and 9.95 cm with values The standard error is 0.123 and the R square value is 0.928, indicating a fairly accurate model. In the weak positive lens experiment, the focal distances measured at distances L = 80 cm, 60 cm, and 40 cm respectively produced average values of 4.42 cm, 4.58 cm, and 4.34 cm with standard values The error is 0.0018 and the R square value is 0.9423, indicating a very precise model. In the negative lens experiment, the focal distances measured at distances L = 80 cm, 60 cm, and 40 cm respectively produced average values of 9.57 cm, 9.47 cm, and 8.95 cm with standard error values of 0.08 and an R square value of 0.967, indicating a very strong model in explaining data variations. This is in accordance with the theory of lens properties, namely that converging lenses generally have the ability to form real images, while diverging lenses often produce virtual images
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