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Ask me about Eyewear!

mhip

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A question: I am seeking the perfect pair of pantos. Specifically, I want a fairly full, nearly perfectly round glass as opposed to the flattened version you find in most contemporary pantos. See, for comparison, one of Truman's glasses.

Most models I have found either have too great a difference between width and height of lens or mess up the shape somehow (too square). Savile Row seems promising though isn't exactly what I am looking for. Does anyone know of alternatives? Surely it cannot be too difficult to find a good pair of wire frames.

View attachment 1455163
TVR just released the 505.
Handmade, Japanese. Google should work.

@JDelage
I have the 506 in black driftwood and I like them a lot. I'd describe them as JMM-lite. Chunky acetate, but not as chunky.
All limited runs, handmade.
 

JDelage

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What does "base 2" means when you read a lens description (e.g., CR39 base 2)?
 

faue

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What does "base 2" means when you read a lens description (e.g., CR39 base 2)?
Base curve. i.e. the front surface power.

Quick overview if anyone cares — ophthalmic lenses are almost invariably meniscus lenses with a plus powered convex front surface and a minus powered concave rear surface. Most lens manufacturers have a few standard base curves and then create the Rx by picking a rear lens power to achieve the desired back vertex power, which is what is actually measured and what you are effectively looking through. Different combinations of front and back surface powers produce varying degrees of optical aberrations, and a particular base curve is selected which minimizes these aberrations for a given lens material and back vertex power. So a base 2 means the front surface has a 2.00 diopter base curve, which translates to a radius of curvature of 0.50mm.
 
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faue

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What are the trade-offs between polyamide and CR-39 lenses? I'm looking at sending a pair of JMM frames out to fit different lenses, and one of the 3 online services I've found uses polyamide (they're also in Australia, so that's a consideration)...
In short, CR39 has better optical quality, Polyamide trades off optical quality for being essentially indestructible.
 

JDelage

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@faue - Thank you. So that number is not relevant for sunglasses with no correction, is it?
 

faue

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@faue - Thank you. So that number is not relevant for sunglasses with no correction, is it?
You can still make a plano lens with a base curve, you’d just pick a rear lens power that neutralizes the front. It would be *approximately* -2.00, but depends on lens thickness and material, as well as frame type and size. Ex: if you had a base curve of 2 in a 3mm thick CR-39 lens, you’d have a back surface power of -2/(1-(.003)*2/(1.498) = -2.01 diopters.
 

faue

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I understand what you tell me. I just wonder why sunglass makers would advertise base 2, base 4 on their models. See for example:
https://www.lunetteriegenerale.com/collections/sun/products/architect (base 2)
https://www.lunetteriegenerale.com/collections/sun/products/cognac-1 (base 4)

It doesn't seem that it's very relevant info...
It’s only relevant in this case if you have a high prescription — if they only offer one base curve, it means with higher prescriptions they won’t be able to pick a different one to compensate for aberrations.
 

JDelage

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What are the pros and cons of Natives Sons vs Ahlem? Looking at one or the other for a pair of readers in acetate...
 

sartorialism

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