According to Sony's website this lens has a zoom factor of 3.8. I currently have an 18-55 lens that came with my NEX-3F that has a zoom factor of ~3.1. Since the 55-210 pics up where the 18-55 leaves off, does that mean you can add or multiply those zoom factors? Is the 55-210 minimum zoom equal to the max zoom of the 18-55 or is there really no correlation between the two lenses?
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2\$\begingroup\$ The earlier question should cover what you need to know. Each lens has its own zoom amount. You can consider your entire range to be the widest to the narrowest, so about 12x — that is in fact the same as multiplying each lens's zoom amount together. But the important part is that the result isn't really a very useful number. \$\endgroup\$– mattdmCommented Feb 8, 2014 at 12:05
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\$\begingroup\$ A lens with 400-800mm focal length would have a 2X zoom (800/400 = 2x), this is not the number you're looking for to describe how much magnification you will get from the lens. The 800mm value, however, is. \$\endgroup\$– Lasse V. KarlsenCommented Feb 8, 2014 at 16:47
1 Answer
The X way of measure zoom is misleading because it does not count where things start. It is only a ratio and this is explained in answers to this question.
The 18-55mm and 55-210mm lenses are correlated because the latter at its widest shows the same viewing angle as the former at its longest. The both offer roughly 3X of zoom but outside of at their 55mm positions, show a completely different field-of-view.
The 55-210mm zooms in more, while you can have a lens which zooms out more like the Sony 11-18mm which would ends where the 18-55mm starts. In more photographic terms, we say the 11-18 is an ultra-wide zoom while the 55-210 is a telephoto zoom, while the 18-55 is a standard zoom.