why lens measure in mm?


Feb 22, 2010
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31
Jurong
#1
hi I'm new in photography. just wondering why all the lens measure in mm. to mm.
what is the basis OF MEASURING? :sweat::sweat:
 

Kit

Senior Member
Jan 19, 2002
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#2
The figures you see on lenses, expressed in mm are the focal lengths(angle of view). Lenses are measured in a number of ways, depending on what you are measuring.
 

ZerocoolAstra

Senior Member
Mar 13, 2008
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#3
hi I'm new in photography. just wondering why all the lens measure in mm. to mm.
what is the basis OF MEASURING? :sweat::sweat:
in secondary school physics, we learnt a topic called 'optics'.
Focal length is covered under this.


ring a bell?
 

ZerocoolAstra

Senior Member
Mar 13, 2008
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#4
lens' focal length measured in mm.
lens' filter diameter also measured in mm...

hahaha...

-- conversation overheard in camera store --
A: Uncle, I want to get a UV filter for my lens.
Uncle: What size is your lens?
A: hmmmm....?
Uncle: I mean... what is the diameter of the thread?
A: hmmmmm.... ?
Uncle: on the lens should be indicated how many mm...
A: oh.... 50mm
Uncle: 50? Sure or not?
A: yeah... it says 50mm something something 1.8
Uncle: No la.... that's not the size. I mean the thread size...
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.
.
 

Redzsky

New Member
Feb 22, 2009
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Nothern Singapore
#5
Noob here also. Is the mm for DSLR lens in 35mm format? And how about those quoted for PnS cam? Eg 28mm - 140mm zoom range, is that in 35mm format?
 

GavinTing

New Member
Oct 16, 2007
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#6
Noob here also. Is the mm for DSLR lens in 35mm format? And how about those quoted for PnS cam? Eg 28mm - 140mm zoom range, is that in 35mm format?
35mm format is the film/sensor size..

For PnS depends on what they say. Some will say 35mm equivalent, some dont etc.. Depending on what they want to portray..
 

kaixiang

New Member
Feb 4, 2009
314
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Bukit Batok, Singapore
#7
Noob here also. Is the mm for DSLR lens in 35mm format? And how about those quoted for PnS cam? Eg 28mm - 140mm zoom range, is that in 35mm format?
If the PnS says 28-140mm it is definitely in equivalent terms. Usually it is something like 4-30mm. All dslr lens show the actual focal length. If you are used to thinking in 35mm focal lengths, do account for the crop factor yourself.
 

Rashkae

Senior Member
Nov 28, 2005
19,105
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#8
Noob here also. Is the mm for DSLR lens in 35mm format? And how about those quoted for PnS cam? Eg 28mm - 140mm zoom range, is that in 35mm format?
Normally it's all in 35mm equivalent, yes. A compact camera may have an actual focal range of, say, 6.3-63mm but the 35mm equiv. is 35-350mm.
 

Dream Merchant

Moderator
Staff member
Jan 11, 2007
9,659
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#9
Lenses are also measured in cm, inches, feet and meters.
 

Mar 1, 2009
130
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16
Singapore (West)
#11
lens' focal length measured in mm.
lens' filter diameter also measured in mm...

hahaha...

-- conversation overheard in camera store --
A: Uncle, I want to get a UV filter for my lens.
Uncle: What size is your lens?
A: hmmmm....?
Uncle: I mean... what is the diameter of the thread?
A: hmmmmm.... ?
Uncle: on the lens should be indicated how many mm...
A: oh.... 50mm
Uncle: 50? Sure or not?
A: yeah... it says 50mm something something 1.8
Uncle: No la.... that's not the size. I mean the thread size...
.
.
.
.
:thumbsup: You light up my day with this.
 

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