[Question] Zoom magnification & Focal Length


Feb 4, 2012
50
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Changi
#1
Perhaps I overlook description but I came across this when I was comparing lenses...
Both lenses were 18-200mm in focal length but one had a 5.6x zoom and the other 11.1x zoom... so heres my question, isnt focal length zoom if it isnt then whats the difference between focal length and zoom magnification... enlighten me please :)
 

spree86

Senior Member
Feb 3, 2009
4,774
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Bishan
www.flickr.com
#2
Marcusluvsgreen said:
Perhaps I overlook description but I came across this when I was comparing lenses...
Both lenses were 18-200mm in focal length but one had a 5.6x zoom and the other 11.1x zoom... so heres my question, isnt focal length zoom if it isnt then whats the difference between focal length and zoom magnification... enlighten me please :)
18-200 is 11.1X zoom. The 5.6X is wrong. Are you sure you didn't mistake f3.5-5.6 as the zoom?
 

May 5, 2009
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16
#3
to get the number of optical zoom, you just need to take the longest focal length and divide it by the shortest focal length, in this case 200mm/18mm = 11.1x zoom.

12-24mm is 2x zoom, and 10-20mm is also a 2x zoom, etc. :)
 

Feb 4, 2012
50
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Changi
#4
thanks guys for the clarification :) i misread the 2 one of which was 55-200 (3.6x) and the other 18-200 (11.1x)
 

Rashkae

Senior Member
Nov 28, 2005
19,105
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#5
Do note that "Zoom" means nothing to photographers. It's purely a marketing term for the totally pointless consumer. After all, a 200mm-400mm is a "2x zoom", and a 10mm-20mm is also a "2x zoom".
 

donut88

Senior Member
Nov 14, 2008
2,182
5
0
#6
Rashkae said:
Do note that "Zoom" means nothing to photographers. It's purely a marketing term for the totally pointless consumer. After all, a 200mm-400mm is a "2x zoom", and a 10mm-20mm is also a "2x zoom".
I used to be at a lost of all these "zoom" gimmicks in the past. Now I'm fully understand after going into DSLR.....
 

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