Results 1 to 17 of 17

Thread: Seg Height Measurement

  1. #1
    OptiBoard Novice
    Join Date
    Aug 2005
    Location
    GA
    Posts
    6

    Seg Height Measurement

    Okay, I keep getting two different answers on this question:

    When measuring a seg height do you measure to the bottom of the lens and add .5mm, or do you measure to the bottom of the frame?

    Thanks in advance!

  2. #2
    Underemployed Genius Jacqui's Avatar
    Join Date
    Oct 2003
    Location
    Frostbite Falls, Mn.
    Occupation
    Optical Wholesale Lab (other positions)
    Posts
    7,359
    Blog Entries
    2
    In the lab we measure to the bottom of the lens.
    Proud Member of the ABE Club!
    Don't feed the Beast...

  3. #3
    OptiBoard Novice
    Join Date
    Aug 2005
    Location
    GA
    Posts
    6
    Do you add the .5 mm to make up for the groove or not?
    Thanks!

  4. #4
    sub specie aeternitas Pete Hanlin's Avatar
    Join Date
    May 2000
    Location
    Hickory Creek, TX
    Occupation
    Lens Manufacturer
    Posts
    4,823
    I usually measured to the bottom of the lens and added half of the frame thickness. So, if you have a chunky zyl frame, you might end up adding 1mm. If you have a metal frame, it usually works out to 0.5mm.

  5. #5
    Underemployed Genius Jacqui's Avatar
    Join Date
    Oct 2003
    Location
    Frostbite Falls, Mn.
    Occupation
    Optical Wholesale Lab (other positions)
    Posts
    7,359
    Blog Entries
    2
    In wholesale work I was always taught the bottom of the lens, period. My customers may be calculating this before I get the Rx.
    Proud Member of the ABE Club!
    Don't feed the Beast...

  6. #6
    Master OptiBoarder mullo's Avatar
    Join Date
    Mar 2001
    Location
    Vancouver, B.C.
    Occupation
    Dispensing Optician
    Posts
    679
    Quote Originally Posted by Pete Hanlin
    I usually measured to the bottom of the lens and added half of the frame thickness. So, if you have a chunky zyl frame, you might end up adding 1mm. If you have a metal frame, it usually works out to 0.5mm.
    Same here.

  7. #7
    Master OptiBoarder Clive Noble's Avatar
    Join Date
    May 2000
    Location
    Israel
    Occupation
    Optical Retail
    Posts
    429
    I don't think it matters which way you take the measurement as long as the person edging and fitting the lens knows how you measured it.

  8. #8
    OptiBoard Professional Lewy's Avatar
    Join Date
    Jun 2005
    Location
    Northampton, England
    Occupation
    Ophthalmologist
    Posts
    180
    I find it better to measure the height above or below the datum line. Flat tops in general lie 2mm below the datum and PAL's tend to sit at about 4mm. See previous post in the Prog lens forum for technique.


    Lewy

  9. #9
    Manuf. Lens Surface Treatments OptiBoard Gold Supporter
    Join Date
    Aug 2002
    Location
    Naples Florida, using AC instead of heating
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    17,435
    Blog Entries
    3

    No discussion issue...............

    Quote Originally Posted by Lewy
    I find it better to measure the height above or below the datum line. Flat tops in general lie 2mm below the datum and PAL's tend to sit at about 4mm. See previous post in the Prog lens forum for technique.
    Lewy
    Thsi issue should not even be discussed. Any lab or lab personale you give an RX to make will work, surface, cut and mount the the lens by following the international rule...................bottom of lens to whatever you indicate
    Chris Ryser
    ________________________________________
    DLO. NA.IC.I.T.PO

    http://optochemicals.com............................. http://arcoatings.com

  10. #10
    Enjoying the education drk's Avatar
    Join Date
    Mar 2004
    Location
    Ohio
    Occupation
    Optometrist
    Posts
    5,592
    Yes, Chris, but do you think that the bevel is "the bottom" or is the most inferior portion of the lens front surface "the bottom"?

    I was taught to do what Pete described...is that not standard?

  11. #11
    Optician Extraordinaire
    Join Date
    Jun 2005
    Location
    Somewhere warm
    Occupation
    Dispensing Optician
    Posts
    2,856
    In over 20 years in the field, I have never worried about the 1/2 mm hidden by the frame. I measure to the lowest part of the lens, and never have a problem.

  12. #12
    Always learning OptiBoard Bronze Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    3,059
    Bottom of the lens. If the edge is beveled then to the bevel apex. A "Box-O-Graph" can be used to confirm the accuracy of your measurement method. Bevel depths are about .3mm for metal frames and about .5mm for zyl. Rolled eyewires may make accurate measurements difficult unless the lens is removed.
    Robert Martellaro
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    “Science is a way of trying not to fool yourself"
    -Richard Feynman
    ~~~~~~~~~~~
    A mime-free zone.

  13. #13
    Bad address email on file
    Join Date
    Apr 2005
    Location
    Windsor, Canada
    Posts
    314
    It should be to the lowest point on the lens, including bevel.

  14. #14
    Manuf. Lens Surface Treatments OptiBoard Gold Supporter
    Join Date
    Aug 2002
    Location
    Naples Florida, using AC instead of heating
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    17,435
    Blog Entries
    3
    Quote Originally Posted by drk
    Yes, Chris, but do you think that the bevel is "the bottom" or is the most inferior portion of the lens front surface "the bottom"?

    I was taught to do what Pete described...is that not standard?
    DRK, Actually the bevel is the bottom. In the old days some lens manufacturer supply some transparent thin rulers, you would place into the frame groove and take you reading where needed...........and that would give you the right measurement. The labs will then use top to bottom meausure,
    Chris Ryser
    ________________________________________
    DLO. NA.IC.I.T.PO

    http://optochemicals.com............................. http://arcoatings.com

  15. #15
    Optical Clairvoyant OptiBoard Bronze Supporter Andrew Weiss's Avatar
    Join Date
    Apr 2004
    Location
    Raleigh, NC
    Occupation
    Dispensing Optician
    Posts
    1,365
    Bottom of the lens, which on a v-bevel is the bottom of the bevel. Like Pete, I estimate. That's how I was taught, some 45 years ago.
    Andrew

    "One must remember that at the end of the road, there is a path" --- Fortune Cookie

  16. #16
    Bad address email on file finklstiltskin's Avatar
    Join Date
    Jul 2005
    Location
    Little Rock, AR
    Posts
    159
    Has anyone here actually had a case where half-a-mm actually made a difference in a patient's adaptability?

    I usually measure to the bottom of the visible portion of the lens and have had VERY few problems in my 8 years of experience.

  17. #17
    OptiWizard
    Join Date
    Mar 2005
    Location
    Indianapolis
    Occupation
    Optical Wholesale Lab (other positions)
    Posts
    372
    Finklstiltskin, it works fine the way you just mentioned. we have been doing it that way for over 45 years with no problems.Though we are very meticulous with the seg or pupil height measurement(within .5mm) we don't worry about the .3, .4,or.5mm bevel depth.Not much of an optician if you can't adjust the glasses for minimal errors. Obviuosly on rimless frames it is measured to the very bottom.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Seg height is the weak link in PAL fitting
    By ilanh in forum General Optics and Eyecare Discussion Forum
    Replies: 54
    Last Post: 01-22-2009, 03:13 PM
  2. My favorite seg
    By Karlen McLean in forum General Optics and Eyecare Discussion Forum
    Replies: 16
    Last Post: 06-03-2005, 06:25 AM
  3. FT28 1.6 Seg Issues?
    By Andrew Weiss in forum General Optics and Eyecare Discussion Forum
    Replies: 5
    Last Post: 12-03-2004, 01:07 PM
  4. Seg Drops Keep Fallin' On My Head
    By drk in forum General Optics and Eyecare Discussion Forum
    Replies: 15
    Last Post: 05-08-2004, 12:31 PM
  5. When to use different seg heights
    By Himyope in forum General Optics and Eyecare Discussion Forum
    Replies: 11
    Last Post: 04-17-2003, 02:14 PM

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
  •  
OptiBoard is proudly sponsored by:
Identity Optical, Younger Optics, Carl Zeiss Vision, Vision Systems, Inc. and Chemistrie Eyewear