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Thread: blue blocking

  1. #1
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    blue blocking

    An old yellowed CR39 lens has blue blocking capability is this right? Can a yellowed lens be used as a blue blocker?

  2. #2
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    Quote Originally Posted by Ray2019 View Post
    An old yellowed CR39 lens has blue blocking capability is this right? Can a yellowed lens be used as a blue blocker?
    IMHO

    the yellow blocks the blue but it is hard to say how much it cut without a Spectrometer.

    Different batch of old lenses may have different result for sure.

    I prefer a new lenses coated properly.

  3. #3
    Master OptiBoarder rbaker's Avatar
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    As CR-39 lenses age they deteriorate. A few years ago I came across some + spheres that had been peacefully sleeping in a box in my garage since I retired in 2002. Took a +2.00 out of its envelope and as expected it was schict brindle yellow/brown. I was also able to break it in half with hardly any effort. The lens was sort of "crumbly" From an impact resistand standpoint, totally unusable.

    If its "yellow" toss it out.

  4. #4
    Rising Star
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    Any full blue blocker will appear yellow / orange or possibly red (yellow tints usually block blue very well - bbut wouldn't rely on it with just an old lens) - most of the coatings that claim to be a blue blocker only block some of the blue.

  5. #5
    Ghost in the OptiMachine Quince's Avatar
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    I'm a big advocate of BluTech. In the right frame, the tint isn't obvious and it is soooo comfortable. Not blue reflections from coatings and no color disruption from yellow lenses. I wear the Classic which they have named 'champange' as a color. They do now offer the Ultra which is almost colorless while being more effective than clear blue filters, but I don't have experience with these.

    As jarralad2 stated, the different versions of blue blocker will be more or less effective at different ranges on the spectrum. Finding the right filter comes down to why you want it.

    https://blutechlenses.com/


    ...I do love the idea though of trying to cash in on 20 year old lenses as developing an added feature though lol
    Have I told you today how much I hate poly?

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