why lens measure in mm?

[glennaguilar]

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]

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]

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]

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...
.
.
.
.

 

[Redzsky]

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]

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]

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]

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]

Lenses are also measured in cm, inches, feet and meters.

 

[kaixiang]

Lenses are also measured in cm, inches, feet and meters.

I have seen cm and inches. But feet and meters :bigeyes:

Telescope? :sweatsm:

 

[Oberon]

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.