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  1. Replies
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    Haha thanks Harry! Looks like I need to invest...

    Haha thanks Harry!
    Looks like I need to invest in a text book.
    Cheers guys.
    LOL and no, we don't still use glass bifocals, but I'm studying and I suppose our examiners think we need to know.
  2. Replies
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    Eliminating vertial and horizontal DPE

    Hey guys

    .. yes, me again!

    Calculate the changes required to the segment specifications to eliminate all vertical and horizontal DPE at the NVP (near visual point) in the following:

    R...
  3. Replies
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    7,063

    Depressed Curve?

    Hi guys,

    Calculate the radius of the depressed curve required to give a total add if +3.25D, if radii of r1 = +87.17mm.
    r2= +348.67mm, are ground on a lens with n=1.523 and n=1.678.

    What on...
  4. Replies
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    Calculating Edge Thickness

    Hi everyone
    I am going through a few example questions, and got to this one and couldn't work my calculator properly. Also, how often does a dispensing optician actually use this equation?

    The...
  5. Replies
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    2,310

    hi there, My name's Whitney. I'm 19 years...

    hi there,

    My name's Whitney. I'm 19 years old, and am a training dispensing optician in New Zealand. Would you be willing to bring someone from overseas?

    Thanks,
    Whitney dell
  6. Replies
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    Also two others! 14) Calculate the...

    Also two others!

    14) Calculate the decentration required to obtain the desired amount of prism in the prescription LE +5.50/-1.50x60 4 base down and 3 base out

    15) Calculate the decentration...
  7. Replies
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    Needing help with prisms

    Hi guys,

    Im still having trouble with this question, can anyone help?

    6) A prescription reads

    RE 5 base up
    LE 9 base out

    I need to equally divide the prism between the two eyes.
  8. Replies
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    Help with prisms!

    Hi guys,

    I'm going through a few questions in my book. For the following, I don't understand differential prisms or really anything in these questions. It doesn't seem to be anywhere in my books!...
  9. Replies
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    woohoo i was right :D Thanks guys!

    woohoo i was right :D
    Thanks guys!
  10. Replies
    3
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    7,157

    Prism decentration

    A +4.50D lens needs to be decentred 4mm inwards to line up with the pupil. If prism is ordered 3 base in, what would be the total decentration of the lens?

    Can someone help? :)

    Whitney
  11. Thanks a bunch Harry. You pointed exactly what...

    Thanks a bunch Harry.
    You pointed exactly what was wrong with the way I have been taught.
    It hadn't been spelt out to me that:
    Mag = Image Distance / Object Distance

    I have also been...
  12. Hi Harry I am still having loads of problems...

    Hi Harry
    I am still having loads of problems with question 1 and 2.
    Could you nudge me in a direction?

    I've done 11 questions so far on the topic and nothing has troubled me until these. I...
  13. Thanks loads Harry. These websites are so...

    Thanks loads Harry.
    These websites are so useful!
    I wouldn't know about them if it wasn't for optiboard.
    I've got question 3.
    I am just working on 1 and 2 as we speak.
  14. Questions relating to magnification and focal points

    Hi there,

    I have a few questions for you all!

    1. An inverted image half the size of an object is required. If the object must be placed 120mm from the lens, what is the power of the lens and...
  15. Replies
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    Help with focal point questions

    Hi there,

    I need some help on a few questions pleaaase :)

    4. An unknown lens has a focal length of +540mm, and is plano-convex in form. The radii are measured to be infinity and -305.95mm...
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    Thanks everyone :)

    Thanks everyone :)
  17. Replies
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    4,117

    Measuring Radii in spherical lenses

    Hi everyone,

    Can someone give me the formula for measuring the radii of a spherical lens?

    Thanks,
    Whit :)
  18. Replies
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    Great thanks! Again, very much appreciated.

    Great thanks!
    Again, very much appreciated.
  19. Replies
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    7,057

    Wow, thank you so much. I've been searching for...

    Wow, thank you so much.
    I've been searching for weeks to try and find someone in my practice that will help me - and I find someone on the internet that spells it out for me!
    I really appreciate...
  20. Replies
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    7,057

    Having trouble with equations - HELP!

    Hi there,

    I am having a few problems with a couple of questions in one of my assignments. Can someone please point me in the right direction?
    I was okay, until they asked me to start mixing and...
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