How do you determine the optical magnification of lenses?


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marsulein

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Jul 12, 2005
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#1
Dear Photo Enthusiasts,

I've just picked up photography roughly 2 weeks ago and I am still very confused on how do you actually find out the optical magnification (a.k.a zoom) just by reading about the lens spec.

For example, let's take a look at this lens which I found from official Nikon website:

AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED

The website says that:

"AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED, a compact, lightweight 11.1x zoom lens that is ideal..."

How do you actually derived the 11.1x magnification from looking at the focal length information?

A very confused Noob,
Mar
 

Redsun

Senior Member
Nov 27, 2005
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www.flickr.com
#2
Dear Photo Enthusiasts,

I've just picked up photography roughly 2 weeks ago and I am still very confused on how do you actually find out the optical magnification (a.k.a zoom) just by reading about the lens spec.

For example, let's take a look at this lens which I found from official Nikon website:

AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED

The website says that:

"AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED, a compact, lightweight 11.1x zoom lens that is ideal..."

How do you actually derived the 11.1x magnification from looking at the focal length information?

A very confused Noob,
Mar
they actually got the 11.1x zoom factor by dividing 200/18
 

Octarine

Moderator
Staff member
Jan 3, 2008
12,516
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Pasir Ris
#5
That means a 70-200 lens has a lower zoom factor than a 17-50? Sounds rather weird and misleading... I prefer the real figures of focal length rather than such marketing bubbles of zoom factor.
 

zac08

Senior Member
Feb 21, 2005
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#6
That means a 70-200 lens has a lower zoom factor than a 17-50? Sounds rather weird and misleading... I prefer the real figures of focal length rather than such marketing bubbles of zoom factor.
This zoom factor is more for the PnS or Prosumers anyway....

I dun think any of the SLR users bother with it....
 

night86mare

Deregistered
Aug 25, 2006
25,541
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www.pbase.com
#7
How do you actually derived the 11.1x magnification from looking at the focal length information?
simply put, the most direct answer is 200/18

the maximum focal length on the lens, divided by the minimum

same goes for any p&s, but you shouldn't care about focal lengths, more about perspective. :)
 

marsulein

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Jul 12, 2005
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#8
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