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  1. Replies
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    Thanks for the excellent reply I mostly get it...

    Thanks for the excellent reply I mostly get it now.

    I suppose in a way by not decentering the lens then the Petzval surface and the far point sphere will not coincide compounding the issue?

    "...
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    Centre of Rotation - Tilt compensation

    Hi,
    The common diagram showing why tilt needs to be compensated does make some sense but could anyone answer a few questions I have regarding this.

    1. The line of gaze doesn't change so by...
  3. Replies
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    Hi, The link takes me to Darryl's Opticampus...

    Hi,
    The link takes me to Darryl's Opticampus site but then reports 'page does not exist' can you help?

    Thanks
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    7,465

    Sorry but that doesn't really answer my question...

    Sorry but that doesn't really answer my question regards FVP versus BVP!
  5. Replies
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    7,465

    Focimeter / Lensmeter Use & design

    I had a thought today and I'm trying very hard, to remember the principles of focimeter/lensmeter design but since i studied this 20 years ago i need some help!

    Focimeter light is projected on...
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    3,391

    Whats different about the liberty though? I have...

    Whats different about the liberty though? I have a pdf which shows me the bevel profiles. It looks similar to the wraps but with a flatter front part of the bevel and no centre 'tram line'. The name...
  7. Replies
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    3,391

    optronics 7e blades

    I have recently acquired a second hand optronics 7e edger. I want to edge wraps but I'm not sure which blade to go for. My options are the Hi-wrap 1, the Hi-wrap 2 or the Liberty blade, (I'm not sure...
  8. with swirls you have to start from the bottom as...

    with swirls you have to start from the bottom as Audiyoda said. Most times we start getting swirls because our pins on the cyl machine are blunting but at the same time you have to check the inserts...
  9. I normally do match the base curve as close as...

    I normally do match the base curve as close as possible. I was really looking for a calculation for the angle of drilling when this can't be achieved. Is this what you mean by Mr Meisters formula and...
  10. possible approximate solution

    To visualise it draw the diagram for deriving the sag formula from Jalie (not got it in front of me so please bare with)

    1. Draw a right angled triangle so that the, short side/opposite = y,...
  11. calculation of drill angle

    Is there an easy way of calculating the amount a hole should be angled, when the base curve of the fitted lens is different from the demo lens. Looks like it should be simple geometry but I'm...
  12. Replies
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    On your program do you mean for a given base and...

    On your program do you mean for a given base and rx what the best p-value would be to minimse oblique astigmatism etc?
  13. Replies
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    I understand that p-value describes its degree of...

    I understand that p-value describes its degree of flattening and the diagram in Jalie shows different p-values for curves i.e prolate ellipse etc. Is there any way of showing p in a diagram, how is...
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    Here's what Jalie had to say about aspherics used...

    Here's what Jalie had to say about aspherics used for low plus.

    'Needless to say. any higher order aspherical surface could be used but,in practice, it would not depart significantly from a...
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    16,834

    As an optometrist I wouldn't be sure if such a...

    As an optometrist I wouldn't be sure if such a statement could be a problem with my insurance. He may be guarded as to whether you would be likely to sue if anything went wrong???
    I do however ...
  16. Replies
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    I'm a little confused. Are polynomal surfaces...

    I'm a little confused. Are polynomal surfaces used for cataract/high plus lenses. After a bit of reading I thought the low plus aspherics were hyperbolic and could be described with a p-value?????
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    Iceberg

    I went to a good seminar on staff. One way to look at staff is to think of there personality like an iceberg. Only one third of an iceberg is visible above the water line. If compared to a staff...
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    Can you still get semi-finished in these types of...

    Can you still get semi-finished in these types of aspheric? Also could you describe the centre 20mm using a p-value so that the best design could be given for the prescription, the remainder of the...
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    What's the difference?

    What's the difference?
  20. Replies
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    9,409

    Spherical equivalent? Is that the mean Rx as i...

    Spherical equivalent? Is that the mean Rx as i described above.
  21. Replies
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    Lens Design & Aspherics

    When choosing the best base curve/p-value for an astigmatic patient is it better to choose the mean RX i.e. Sphere + (cyl/2), the highest meridian or the lowest meridian.:hammer:
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    I agree but we keep getting asked for them...

    I agree but we keep getting asked for them especially for sunglasses!!!
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    Is one of them more scratch resistant?

    Is one of them more scratch resistant?
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    Whats the difference between MR-7 and MR-10? Are...

    Whats the difference between MR-7 and MR-10? Are data sheets available on all the MR materials?
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    British Optician

    I think the Masters idea is really good. I have met plenty of opticians who seem to view there job as just good money. I think we have a duty to our patients to be the best we can be.
    As far as...
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