With 35 mm film cameras, the 35 mm refers to the film size, not to be confused with the lens size. A 50 mm lens is usually considered the normal or neutral size, with a magnification factor of one. A 50 mm lens has no magnification. So, as the size (millimeters) of the lens become larger, the magnification of the image becomes greater. A 100 mm lens gives 2 times magnification, and makes the subject appear 2 times closer and gives less viewing area; a 200 mm lens gives 4 times magnification, and so on.
A 25 mm lens would make the subject look farther away by a factor of 2 and give a wider viewing area. Fisheye lenses, usually about 8 to 15 mm, give a very wide view and negative magnification. The increased area appears as a distorted "fisheye" view.
Digital cameras have electronic image sensors which are usually smaller than the area of film exposed in a 35 mm camera, and lenses will have a different magnifing effect. It is not a problem, though, as the manufacturer almost always gives a calculation of the equivalence of the lens with the digital camera compared to a 35 mm film camera, and calculates the magnification of the lens of the digital camera.
In standard film camera reference which is commonly used, a 50 mm lens equals a neutral value, or 1x magnification, so a 12x lens would be 600 mm.
6-24 magnification, 50 mm lens
It depends on the actual focal length. For a 35 mm format lens, 200 mm is about 4x magnification, to get 20x you'd need a 1000 mm lens. For smaller formats, such as 8 mm or a camcorder, find the focal length for normal view, then multiply by 20.
That's 80 power.
15 * 30 = 450 ------------
the eyepiece lens magnification X the magnification of the objective lens.
Simply, multiply the magnification of the ocular lens times the magnification of the objective lens you have in place.
The total magnification is equal to the magnification of the eyepiece multiplied by the magnification of the objective lens. So in this case the objective lens would need to be 100X.
15 * 30 = 450 ------------
30
Each objective lens has a different magnification. Multiply the magnification of the eyepiece by the magnification of the objective lens to produce total magnification. For example, a 10X ocular lens and a 40X objective lens will produce a total magnification of 400X (10 x 40 = 400).
multiply the magnification of the eyepiece by the magnification of the high objective lens. for example, if the eyepiece magnifies x10, and the high objective magnifies x40, then the total magnification would be 400x