10x50 not the same as 5x? This one says 10x Frequently when we go buy Binoculars or see some on Amazon.com, it says 10x20 or 7x50. Does 10x20 not mean 10x magnification but 2x? That number comes from 20 / 10. So 7x50 is 7x (by 50 / 7)... and 10x20 is actually 10x20mm? Are those the focal length of the eyepiece versus the object lens, so whatever they are, a division can give the real magnification power?
10x20 is 10x magnification and a 20 mm aperture. The 20/10 is 2 mm exit pupil. for the same reason 7x50 is a 7x magnification, but for a different reason than stated above. you can read more at astronomy.com if you're intersted link is http://www.astronomy.com/asy/default.aspx?c=a&id=2225