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  1. #1
    That Boy Ain't Right Blake's Avatar
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    Question

    I would like to start a little optical trivia contest at work to help motivate my fellow associates to learn more. Sort of like "Who Wants to Be a Millionaire", but for maybe a dollar each week (it's coming out of my pocket, so it won't be much).
    Any suggestions of possible questions would be appreciated. Just think, you'd be helping future opticians!

    ------------------
    Blake

  2. #2
    Master OptiBoarder karen's Avatar
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    Here's a good one- What does CR 39 stand for?
    It was Columbia(n?) Resins 39th try that got the formula right for plastic lenses

  3. #3
    Rising Star
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    The answer to the CR-39 question was close. The original Columbian Resin #45 was for aircraft windshields.

    [This message has been edited by Wes Trayner (edited 06-05-2000).]

  4. #4
    Objection! OptiBoard Gold Supporter shanbaum's Avatar
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    ...and it wasn't developed for use in lensmaking; it was first used as a bonding agent in aircraft fuel tanks. Robert Graham (founder of Armorlite) first had the inspiration to cast lenses from it. Then, after a number of years in the optical industry, he became an advocate of eugenics. Coincidence?

  5. #5
    sub specie aeternitatis Pete Hanlin's Avatar
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    ...it is also interesting to note that Transitions "plastic" is CR-309 (how many formulas have Columbian Resin gone through?).
    Pete

  6. #6
    sub specie aeternitatis Pete Hanlin's Avatar
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    Here's a new question...
    What is the difference between a Centrad of Prism, a Diopter of Prism, and a Degree of Prism?

    Pete

  7. #7
    Master OptiBoarder Jeff Trail's Avatar
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    Unhappy

    OK Blake lets add to this "million" dollar game....hmmmmmmm start easy and build up...

    1) The formula to get a "quick" estimation on a stock SV and the cutout diameter needed.
    ie. You have a 56/18 frame, ed-59 and a PD of 62...what stock diameter SV blank would work?

    2)I have a frame with a PD of 64 but needed a PD of 61.. the power is a -2.50 OU..how much prism is induced? (hint Prentice :-)

    3) I have a compound prism of 4^ out and 4^ up...what is the resultant prism?

    4)*I have two pair of glasses..both the same refractive power and base curve (say a +2 ou, curve of 6.25 (sag 3.75)...BUT the ocular curve in one is a -4.12/-4.12 and the other pair has an ocular curve of -4.50/-4.50...how is this so?

    * note..every post like this should have a trick question..don't ya think? :-)

    Those four should keep em busy for a day or so and it's the basic formula's that we all should know...oh I guess you could always throw in the formula to figure a "slab" but thats pretty boorrring stuff :-)

    Jeff "is that your final answer" Trail




  8. #8
    Master OptiBoarder karen's Avatar
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    Originally posted by Wes Trayner:
    The answer to the CR-39 question was close. The original Colubian Resin #45 was for aircraft windshields.
    I have to remember to tell that to the Doctor that told me that-thanks for setting me straight before I tried to impress too many people with it! :) Not that you guys haven't all seen it and decided I might be hare-brained!!

    ------------------
    Because I'm the princess, that's why

  9. #9
    Bad address email on file Darris Chambless's Avatar
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    Originally posted by Pete Hanlin:
    Here's a new question...
    What is the difference between a Centrad of Prism, a Diopter of Prism, and a Degree of Prism?

    Pete
    The difference is the schooling that one gets and the time frame. Centrad I believe is the oldest term, Degree the next and Diopter the newest term.

    How was my guess?

    Darris "Guessing is like a fine wine. You feel proud until someone says it sucks." Chambless


  10. #10
    sub specie aeternitatis Pete Hanlin's Avatar
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    Actually, "centrad," "diopter," and "degree" are not synonymous terms. As we all know, a diopter of prism will deviate light one centimeter over the span of one meter. A centrad will also deviate light by one centimeter over the span of one meter- but the meter is measured as an arc with a radius of one meter (meaning that a centrad is a slightly more precise, if less used, measure of prism than the diopter). Finally, a degree is a measure of the actual angle (in degrees) by which light is deviated within the lens. One degree is actually equivalent to about 1.75 diopters (and one diopter is equivalent to about 0.57 degrees). However, the terms "degree" and "diopter" are used synonymously today (BTW, the designation for a centrad is an upside down diopter symbol).

    Pete "Isn't that edifying?" Hanlin
    P.S.- D minus 15 days until the Invasion of the Big Easy!

  11. #11
    That Boy Ain't Right Blake's Avatar
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    Idea

    4)*I have two pair of glasses..both the same refractive power and base curve (say a +2 ou, curve of 6.25 (sag 3.75)...BUT the ocular curve in one is a -4.12/-4.12 and the other pair has an ocular curve of -4.50/-4.50...how is this so?

    * note..every post like this should have a trick question..don't ya think? :-)

    Well, I'm tricked! I think I'm gonna take the money and run. Guess I haven't spent enough time in the lab. But just for grins, I'm gonna guess it's because the lenses are made of different materials.

    Anyway, thanks everyone for your suggestions. This should be an interesting quest for knowledge.

    ------------------
    Blake

  12. #12
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    All I can say pete is "Wow!" I am impressed and well-armed for the next ******** know-it-all I run into who doesn't read this board.

    Thanks

  13. #13
    Master OptiBoarder Darryl Meister's Avatar
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    Originally posted by Pete Hanlin:
    Actually, "centrad," "diopter," and "degree" are not synonymous terms... A centrad will also deviate light by one centimeter over the span of one meter- but the meter is measured as an arc with a radius of one meter (meaning that a centrad is a slightly more precise, if less used, measure of prism than the diopter)... One degree is actually equivalent to about 1.75 diopters (and one diopter is equivalent to about 0.57 degrees)...
    As an added bit of optical trivia for this answer (or a trivial bit of optics?)... I'll add that a "prism diopter" is not a true unit of measure, while the centrad and degree are. The effective value of a prism diopter changes as the angle of deviation increases, so it is not a uniform unit of measurement... Meaning that 8 prism diopters do not produce the same amount of deviation as 2 x 4 prism diopters. For low prism powers, like we typically deal with in ophthalmics, the units are all almost equivalent.

    Best regards,
    Darryl

  14. #14
    RETIRED JRS's Avatar
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    Question

    For Jeff's Questions -
    1) a 71mm stock lenses would just work.
    2) about .375 diopters per eye.
    3) 5.65 diopters
    4) the lenses with the -4.12 ocular is Poly and the -4.50 ocular are CR-39.

    Do I win a prize?

    [This message has been edited by JRS (edited 05-30-2000).]

  15. #15
    Master OptiBoarder Jeff Trail's Avatar
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    Redhot Jumper

    [QUOTE]Originally posted by JRS:
    [B]For Jeff's Questions -
    1) a 71mm stock lenses would just work.
    2) about .375 diopters per eye.
    3) 5.65 diopters
    4) the lenses with the -4.12 ocular is Poly and the -4.50 ocular are CR-39.

    Do I win a prize?

    Yea.. you know some basic rules WE ALL should know :-).. you might be surprised by some of the E-M's I got and how far OFF they were.. pretty scary, when some were signed with ABO,NCLE beside the name :-)
    BTW the lens were 1.60 index and CR39 to the "trick" question...but it was close enough to the index of poly that we'll give you that one :-)
    If I had a penny for every optician that called me and asked me "how do you know it's high index?".. or "poly" etc. etc. ... and I explain to them how to check it with a clock or the ever standard "drop it and listen to the sound" :-).. and the worst part is I actually have accounts that do NOT even have a lens clock!! :-)
    The resultant prism usually comes up when dealing with someone that writes up the RX in compound and then when the "prism" does NOT match what they wrote down along an oblique axis they usually tell me how I did it incorrectly :-)
    I wrote up a small booklet (about 30 pages) of all the formulas and tricks I could think of that might come in handy and probably less then 10% of my accounts actually used it or probably even read it :-)
    I still think the key to it is education and actually learning the "why" behind the whole process is important, not just sell them something because the "spiff" is more :-)
    I'm not going to "bash" people but here are some examples of the answers that were way off...had from 50 mm to 75 mm answer to the first..I could see the rounding up to the 75 mm since most stock lens come 70's or 75 mm.
    The second question for some reason "confused" alot of people and it could actually be a trick question or answer, if you prefer. Possibly you could take a mono fit and it could increase one eyes induced prism and show a decrese in the other.. but I was trying to keep it simple and wanted to just use a basic set of numbers to work from.
    The third question was a toss up.. with three ways to look at it.. some said 4^, others came up with 16^ :-).. and some were right in the right range 5.25'sh to 1/2 I can live with that (so your equation got a little soggy or you dribbled on your work sheet :-)BTW (^2)+(^2)= total^2
    The last one it was all over the place.. mostly people got it "correct" in the basic answer of saying it was "mixed" materials.. but only a few (one that E-M me) actually knew the formula to tell based on front/occular curve=power what was the index of the materials.
    I thought most were very "basic" questions but I wish I would have gotten better more exact answer's :-)...
    I had two guys that come on here to blast me that work for me, always digging into my posts so they can ride me when I make a mistake :-)I look at it this way I keep all the books at my lab where they can find anything we usually talk about on this sight and it drives them into "digging" into it and they gain from trying to be able to give me a hard time :-)

    Jeff"crack the whip..optically speaking"Trail

  16. #16
    RETIRED JRS's Avatar
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    Jeff, sure either 1.6 or 1.586 will 'round' to -4.50 ocular. Unrounded a 1.6 (1.595) will be about -4.50767 and Poly would be -4.48053. Assuming both are 1.6 centers.

    The question (and therefore the answer) that is the most mis-leading is the minimum cutout using a 59ED. The ED used by most is by using a ruler across the diagonal of the frame. If, from FC (frame center) the radius to temporal-bottom = 33, but from nasal-up is 26, the sum is 59, but your typical formula won't work if decentration is IN. the real answer would be to double 33 and add the offset.

    And yes, you are correct, I do know some 'basic' rules.
    PS - no worksheet sogginess or dribbling. And the answer to the resultant prism question is NOT 5.25 diopters, unless you need to round it off to 'your' nearest prism ring, or you're using some other indices.

    [This message has been edited by JRS (edited 06-01-2000).]

  17. #17
    That Boy Ain't Right Blake's Avatar
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    "The last one it was all over the place.. mostly people got it "correct" in the basic answer of saying it was "mixed" materials.. but only a few (one that E-M me) actually knew the formula to tell based on front/occular curve=power what was the index of the materials."

    Well, I must humbly admit that I don't know that formula, but I would be most interested to learn it!
    Thanks everyone for all the suggestions. I posted the questions yesterday. They were, in my opinion, extremely simple, but you've gotta start somewhere.

    Blake
    "Like Regis, only... well, okay, nothing at all like Regis"

  18. #18
    Master OptiBoarder Jeff Trail's Avatar
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    Redhot Jumper

    Originally posted by Blake:
    "
    Thanks everyone for all the suggestions. I posted the questions yesterday. They were, in my opinion, extremely simple, but you've gotta start somewhere.
    "
    Blake...

    Actually I usually try to start with the basic's as well when I hire people into the lab. I try to get them to learn the actual "physical" nature of what they are doing and not just depend on a "program" to figure out the optics for them.
    To learn something if you have the basic foundation to build on it's almost like working with a set of tinker toys...you start with the basic thing and each thing links to it and the more complicated the optics it can still be broken down into those basics and built right back up.
    It never fails in the lab they learn the basic rules that I start pounding into them and then one day while going through the steps you can almost see the "light bulb" going off over their heads.."oh, that's what happens when I do this and then the result is this"..LOL
    I'll tell you I probably have sent more then 15 or so people onto taking the ABO and NCLE and the OD's in my area love hiring out of my lab because they know the optician knows optics inside out as well as knowing and working with a wide range of optical problems and ways to solve it.
    I don't mind in the least sending staff I trained out into the accounts because it makes life easier on me and the opticians have gained by working with me and know that they can drop by or call any time with any problems, so it works to everyone's benefit.
    I know that some people who I have hired have "experience" already, but you would be amazed that the experience is based on what a surface program tells them what to do, and the types of designs and materials are very limited.. Especially if they came from a "chain" store lab.
    Well, you went with the basics.. now you can start with the next step... now you can start with the materials and designs..
    here is a few questions...

    1) What's abbe value and why is it important and what does it signify?

    2) What is the types of physical surfaces you can use and the ways they should be fit and dispensed..and the benefits of those designs
    ( this would be a long list depending on the experience of the staff:-)

    3) What is the difference in PGX and Transitional lens, besides the obvious one being glass the other a "plastic" (since both are available in different materials I would stick to making it two basic groups, its the "reaction" answer that's important)
    A sub question to this one is also what "activates this "change" in the two choices?

    4) Why do you fit mono-pd and have panto tilt in aspherical surfaces? PALs? etc. etc.


    These 3 of 4 might make them have to dig a little deeper.. if they started with those you posted maybe you should save the harder ones for later :-)

    Isn't this fun?.. I do this about every day with the people who work for me.. and they just love trying to trick me.

    JeffT




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