m = h 2 /h 1 = v//u = (f-v)/f = f/(f+u) This equation is valid for both convex and concave lenses and for real and virtual images. Please note that the magnification formula is applicable both in convex lenses and concave lenses. Magnification - definition Magnification of a lens is defined as: m = O I = u v Note: Sign convention must be followed while using formula for magnification. ∣ m ∣ > 1 image is magnified. Plug your data into the formula and solve. On the side of the casing is a series of numbers that includes a number followed by x, as 10x. Finding the magnification of each lens requires examining the casing of each lens. Prev Page ; Next Page ; Related Topics . In this case, your 300mm lens would have a magnification of 6 (6x). Note that the entry pupil at maximum aperture is also the diameter of the front lens. ∣ m ∣ = 1 image is same size as object. From there, we can say that the magnification of a lens is equal to the focal length divided by 50. The magnification produced by a lens can be calculated using the equation: $magnification = \frac{image~height}{object~height}$ Magnification is a ratio of two lengths, so it has no units. If your answer is greater than 1, that means the image is magnified. If your answer is between 0 and 1, the image is smaller than the object. Using lens formula the equation for magnification can also be obtained as . This 10x shows that the lens magnifies an object to appear ten times larger than reality. Prev Page; Next Page ; Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail. Hence, it can be positive or negative. The magnification (m) of lens can also be calculated in terms of image distance (v) and object distance (u), if we do not know the size (height) of object and image. Finally, if your answer is negative, that means the image is upside down. Using this simple formula with the zoom lens, at its longest focal length, 300mm, it does have a magnification factor of 6 (300/50), but at its shortest focal length, 30mm, the magnification factor is … Depending on the manufacturer, this magnification number may appear at the beginning or at the end of the number sequence. ∣ m ∣ < 1 image is diminished. Thus, m = m = Where, v = image distance u = object distance. To calculate magnification, use the following formula: magnification = the height of the image ÷ by the height of the object. This diameter may be calculated using the following formula Φaperture = f F For our telephoto lens at full aperture, diaphragm has a diameter of 125 mm (f/4) and 15.6 mm at its smallest aperture (f/32).