I admit, I wear the “cheeters” for eyeglasses. The +2.50 is pretty close to what I need to survive. They are only $10 vs. $308.79 cash outta pocket, then sat upon.
I understand an 8-base polarized in a prescription is available for around $600, last I checked.
So what is the hold up on an affordable pair? The cheapie reader market has exploded in the last few years. Now chicks can have a pair for each day in the week.
The polarization process has some distortion through application, as it is a film, I understand this as well, but c’mon, it’s like 2000 or some shit.
I heard that they apply that “camo” to surfaces by dipping into a pool of colors that were somhow imissible (sp, and is that the right word?) and the pattern adheres to the surface. Maybe like electroplating, I don’t know, a buddy of mine toured Matthews bow shop once.
Since plastic sucks when it comes to applying a charge to attract a dissolved solid,(using a laser-printer as a model) I would think the lens would have to be submersed in the polarization au jus, and hit with a laser, very quickly across the surface in parallel lines. Result is distortion-free polarization without affecting the magnification of the lens.
WTF? I’ve solved it, why don’t you go make it happen.
Cheaters are what Clark Kent wears: they have no distortion at all. That is because Clark Kent doesn’t need his vision distorted as he has perfect vision.
Some people wear cheaters because they think glasses make them look smart.
Other than figuring out that you are talking about glasses, your OP is in penetrable to me.
While the writing isn’t ideal, I think it’s 100% clear he/she is saying there is some fancy feature avalable on eyeglasses called “8-base polarization”, and wants to know when it will be, or why it can’t be, available on cheapo Walgreens $10 reading glasses.
A little searching and Wiki-ing didn’t turn up an obvous answer to what 8-base meant, but it’s clearly a popular marketing term. Whether there’s any optical science behind it I can’t say.
FYI, the word is immiscible. And the OP used it correctly.
OK, first off: “8-base,” in optics jargon, means the lens has a base curve of 8 diopters. This is a very curved lens, and will “wrap around” more than a lower base curve. I can’t imagine why this term would be applied to polarization.
Next: polarizing film can’t be applied by dipping the lens in “juice”; a moment’s thought should bring on the realization why that’s impossible. Polarizing film is manufactured by rolling or stretching an appropriate material (like polyvinyl alcohol) until it acquires the necessary molecular orientation. The film is then applied to the lens (at least one process uses epoxy to attach the film). How can a liquid maintain that orientation? I don’t know of any material that’s going to make that laser idea work (at least not on finished lenses).
Aside: I’m curious as to why the OP is set on an 8-base lens, and why it’s become such a popular advertising phrase. There is some optical benefit to using a higher base curve, but it’s not what I’d call a big deal.
Also: as far as I know, “camo” lens tinting is applied in successive steps, not in a pool of immiscible dyes. It could be done, I suppose, but it sounds like a frustrating and error-prone process.
Finally: I don’t know much about the economics of the lens industry, but it’s obvious to me that both 8-blanks and polarized lenses are manufactured in plenty, and that the reason for the high cost is that there’s low demand for that particular combination – why would there be a large market for polarized readers? Is there THAT much beach reading going on?
Not pure readers, but polarized sunglasses with “bifocal” reading insert lenses are darned handy for fishing. The polarized lenses cut the glare and greatly improve the ability to see fish under water. As for the reading lenses, even with my long arms it is hard to tie fishing knots at arms length!
I had assumed the +2.50 referred to diopters. Is that right? Does this mean he’s talking about starting with an 8 diopter lens, that is then ground to a total of 10.50? Or what?
ETA: Does the +2.50 refer the bifocals like Kevbo is describing?
No, an ophthalmic lens is curved, and the curvature of both surfaces is measured in dipoters (a diopter is an inverse meter; optometric diopters are inverse meters of focal length, which is related to the curvature (inverse radius) by the index of refraction). The power of the lens is the difference between the base curve (usually the front of the lens) and the…um, other curve (back of the lens). A lens with equal curvature front and back has no corrective power. For a hyperopic patient, the lens might have a curvature of +8 in front and +5.5 in back, creating a convergent lens of power +2.5. My glasses are, I think, +2D base in front and +9 to +10 in back, for a prescription of -7.something. you can also measure the back surface of the lens toward the lens, which will give a negative number, which you would then add to the base curve, but it comes out the same.
No, the +2.5 in the OP refers to the overall power of the lens, although in knot-tying glasses, it would be the strength of the “reading segment,” since the rest of the lens is neutral. There are lots of those out there, so I assume the OP is looking for full-lens readers.
Finally, a disclaimer: the math here is theoretical, and actual curvatures, strengths, and such will vary a bit.
Yeah, but that’s not what the OP asked for, and I don’t see that there’s going to be a large market for what he wants. Those high-curvature lenses are usually used outdoors and in safety glasses, polarized lenses are almost exclusively used outdoors, and full-frame readers are meant for, well, reading, which is largely an indoor activity.
Of course, as a middlin’ high myope in his 40s, I’m not exactly dripping with sympathy for the OP. You want prescription sunglasses? Buy 'em, ya cheap bastid.
