Results 1 to 11 of 11

Thread: Minimum focus distance - industrial definition?

  1. #1
    Senior Member zoossh's Avatar
    Join Date
    Nov 2005
    Location
    Singapore
    Posts
    8,725

    Default Minimum focus distance - industrial definition?

    It is a little confusing here for me.

    By right, minimum focus distance should be measured from the nodal point of the lens to the subject in focus, although some mentioned it can be measured from the front of the lens to the subject in focus.

    Does all brands follow the first definition (from nodal point) in their specifications? Or to the fellow seniors here, does any brands use the 2nd definition for their specification?

  2. #2
    Senior Member giantcanopy's Avatar
    Join Date
    Feb 2007
    Location
    SG
    Posts
    6,232

    Default Re: Minimum focus distance - industrial definition?

    Working distance is from front element to the subject.

    Ryan

  3. #3

    Default Re: Minimum focus distance - industrial definition?

    Quote Originally Posted by zoossh View Post
    It is a little confusing here for me.

    By right, minimum focus distance should be measured from the nodal point of the lens to the subject in focus, although some mentioned it can be measured from the front of the lens to the subject in focus.

    Does all brands follow the first definition (from nodal point) in their specifications? Or to the fellow seniors here, does any brands use the 2nd definition for their specification?
    what is the "nodal point" of the lens?

  4. #4
    Senior Member giantcanopy's Avatar
    Join Date
    Feb 2007
    Location
    SG
    Posts
    6,232

    Default Re: Minimum focus distance - industrial definition?

    Image of the aperture as seen from the front of the lens.
    also referred to as the entrance pupil ( the exit is vice versa ).
    All light rays shld pass thru it, with the principal ray cutting thru its centre
    In filmology, knowing the nodal point enables u to pan the lens about it without displacing the subject.

  5. #5
    Senior Member zoossh's Avatar
    Join Date
    Nov 2005
    Location
    Singapore
    Posts
    8,725

    Default Re: Minimum focus distance - industrial definition?

    Quote Originally Posted by zaren View Post
    what is the "nodal point" of the lens?
    a point determined by the optical lines, somewhere between the front and rear elements, sometimes outside.
    Last edited by zoossh; 9th March 2008 at 03:33 PM.

  6. #6
    Senior Member zoossh's Avatar
    Join Date
    Nov 2005
    Location
    Singapore
    Posts
    8,725

    Default Re: Minimum focus distance - industrial definition?

    Quote Originally Posted by giantcanopy View Post
    Working distance is from front element to the subject.

    Ryan
    does all brands follow this convention and quote their MFD from the front element?

  7. #7
    Senior Member
    Join Date
    Mar 2004
    Location
    Central West
    Posts
    1,952

    Default Re: Minimum focus distance - industrial definition?

    Most manufacturers will quote the minimum focus distance as the distance from the subejct to the focal/film plane. Don't know of any manufacturers that will use a different definition.

    The distance from the front of the lens to the subject is referred to as the minimum working distance (different from minimum focus distance above), not all manufacturers will specify this.

    Also, your use of "Nodal" point of a lens is incorrect. The Entrance pupil (http://en.wikipedia.org/wiki/Entrance_pupil) and the Nodal point (http://en.wikipedia.org/wiki/Cardina...)#Nodal_points)

  8. #8
    Senior Member zoossh's Avatar
    Join Date
    Nov 2005
    Location
    Singapore
    Posts
    8,725

    Default Re: Minimum focus distance - industrial definition?

    Quote Originally Posted by gooseberry View Post
    Most manufacturers will quote the minimum focus distance as the distance from the subejct to the focal/film plane. Don't know of any manufacturers that will use a different definition.
    ic. you mean they usually add the image distance and object distance together for the shortest focal length of the lens?

  9. #9
    Member
    Join Date
    Oct 2004
    Location
    Hougang
    Posts
    598

    Default Re: Minimum focus distance - industrial definition?

    MFD is the distance from subject to film plane... This is true for most if not all manufacturers... Also, on cameras, the film plane is being marked out near the hot shoe area(A white line in Canon's case)... Thus the MFD is measured from this 'white line' to subject...

    Working distance as mentioned by giantcanopy is the distance between the subject and front element of the lens.... This term is quite commonly used in macro photog where being too close to ur subject (too short a working dist) can alarm ur shooting subjects...
    Clear Vision, Swift Action, Good Results.
    imouyang.multiply.com/photos

  10. #10

    Default Re: Minimum focus distance - industrial definition?

    Quote Originally Posted by zoossh View Post
    It is a little confusing here for me.

    By right, minimum focus distance should be measured from the nodal point of the lens to the subject in focus, although some mentioned it can be measured from the front of the lens to the subject in focus.

    Does all brands follow the first definition (from nodal point) in their specifications? Or to the fellow seniors here, does any brands use the 2nd definition for their specification?
    The markings on the lens is graded in distance from the film plane to the subject.

  11. #11

    Default Re: Minimum focus distance - industrial definition?

    Quote Originally Posted by zoossh View Post
    does all brands follow this convention and quote their MFD from the front element?
    No, that's just the working distance. AFAIK, the convention for focusing distance (lens marking) is always to the film plane. There is a standards body governing all these conventions. CIPA is one of them. http://www.cipa.jp/english/index.html
    Last edited by lsisaxon; 10th March 2008 at 11:43 AM.

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
  •