Results 1 to 11 of 11

Thread: why lens measure in mm?

  1. #1

    Default why lens measure in mm?

    hi I'm new in photography. just wondering why all the lens measure in mm. to mm.
    what is the basis OF MEASURING?

  2. #2
    Senior Member Kit's Avatar
    Join Date
    Jan 2002
    Location
    Upper Bukit Timah
    Posts
    11,650

    Default Re: why lens measure in mm?

    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.

  3. #3
    Senior Member ZerocoolAstra's Avatar
    Join Date
    Mar 2008
    Location
    rainy Singapore
    Posts
    9,523

    Default Re: why lens measure in mm?

    Quote Originally Posted by glennaguilar View Post
    hi I'm new in photography. just wondering why all the lens measure in mm. to mm.
    what is the basis OF MEASURING?
    in secondary school physics, we learnt a topic called 'optics'.
    Focal length is covered under this.


    ring a bell?
    Exploring! :)

  4. #4
    Senior Member ZerocoolAstra's Avatar
    Join Date
    Mar 2008
    Location
    rainy Singapore
    Posts
    9,523

    Default Re: why lens measure in mm?

    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...
    .
    .
    .
    .
    Exploring! :)

  5. #5
    Member
    Join Date
    Feb 2009
    Location
    Nothern Singapore
    Posts
    23

    Default Re: why lens measure in mm?

    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?

  6. #6

    Default Re: why lens measure in mm?

    Quote Originally Posted by Redzsky View Post
    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..
    Meow!

  7. #7
    Member
    Join Date
    Feb 2009
    Location
    Bukit Batok, Singapore
    Posts
    314

    Default Re: why lens measure in mm?

    Quote Originally Posted by Redzsky View Post
    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.

  8. #8

    Default Re: why lens measure in mm?

    Quote Originally Posted by Redzsky View Post
    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.
    Alpha

  9. #9

    Default Re: why lens measure in mm?

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

  10. #10
    Member
    Join Date
    Feb 2009
    Location
    Bukit Batok, Singapore
    Posts
    314

    Default Re: why lens measure in mm?

    Quote Originally Posted by Dream Merchant View Post
    Lenses are also measured in cm, inches, feet and meters.
    I have seen cm and inches. But feet and meters

    Telescope?

  11. #11
    Member
    Join Date
    Mar 2009
    Location
    Singapore (West)
    Posts
    130

    Default Re: why lens measure in mm?

    Quote Originally Posted by ZerocoolAstra View Post
    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...
    .
    .
    .
    .
    You light up my day with this.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •