Eye glasses

[shewhorn]

I wasn't really sure where to put this but since my primary use will be for editing images to print, and evaluating prints I figured this was the best forum for my intended use.

So it's time for some eye glasses.

Like camera lenses I suspect there's a fair bit of difference in optical quality from one lens to another and I was wondering if there's a particular brand or build process I should be looking for? Many of the search results I seem to have come up with so far are polluted with folks selling glasses.

What I have dug up so far is that it seems a higher Abbe Number = better optical quality (lower chromatic abberations) and I probably want the lens made out of actual glass instead of plastic.

Has anyone ever done a comparison between say, a glass lens and a Sola Spectralite? How big of a difference is there in optical quality (I guess for a similar prescription the glass would have an Abbe value of 58 and the Sola Spectralite, 47... is there a quantifiable difference between the two)? Seems like it would be next to impossible to do a comparison given the prescription nature of glasses.

Your thoughts are much appreciated!

Cheers, Joe

[Richard Morwood]

Hi Joe
Your question is best taken to an optometrist or dispensing optician who actually knows your eyes, your prescription, the lens design you intend using (single vision, bifocal or varifocal) and the frame you intend glazing. I am an optometrist and your question is a bit like "how long is a piece of string". There are too many variables and without knowing those an answer is almost impossible to give.
You are correct in what you say about the abbe number but unless your prescription is "high" then normal glass or plastic is going to be fine. Why glass over plastic? Modern plastic lenses with AR coatings are very tough, transparent and often every bit as good to look through glass. Here in the UK I would estimate that glass lenses account for possibly <5% of lenses dispensed, and in my practices I would say <1% and those are to people who think they won't scratch rather than any superior optical quality glass might have.
The optical design is more important than things like abbe numbers, etc. Aspherical designs generally improve visual performance of the lens, and some manufacturers offer tailor-made lenses where the fit of the frame is taken into account when manufacturing the lenses. This gives the wearer the best possible vision through them without some measurements being taken as "averages", such as the wrap of the frame, how far the lens is from your eye, the angle the lens makes in front of the eye, and so on. Depending on your prescription and intended type of lens this may be worthwhile, but it could also be totally unnecessary.
As I said lots of variables and your eyes are so individual you are best finding an eyecare professional who knows what they are talking about and whom you trust. I am sure they will be able to give you exactly what you need.
Hope this is of some help.
Regards
Richard

[PeterAit]

I think you are getting way too obsessive. Eyeglasses are eyeglasses, tens of millions of people wear them every day, it is not rocket science! My experience is to go with a reputable independent shop, stay away from Costco and Walmart and the like. In other words, don't be cheap!

[shewhorn]

Thanks Richard. Peter, I wouldn't say I'm being obsessive. Pick up any camera lens and then pickup another of the same focal length but a different brand and there's going to be differences in optical quality. Same holds true for binoculars, telescopes, etc. Eyeglasses are lenses so I would assume that there's differences from one to another... or perhaps not. Where the other devices I mentioned have multiple elements, eyeglasses only have one so perhaps the error in a single lens isn't such a big deal as there isn't a cumulation of errors across multiple elements. I don't know as I've never worn glasses and I'm interested in knowing what people's personal experience is. I never like to rely upon one source of information, I prefer to have a few points of data before spending (what to me) is a lot of money. One would expect an optician to have accurate information but everyone has different motivations.

Cheers, Joe

[Richard Morwood]

Hi Joe
I have to agree and disagree with both you and Peter. Yes optical systems are much more complex than a single lens and therefore the difference between a good camera lens and a poor one can be huge.
Peter is correct that millions wear them every day and that a reputable independent is going to give you the best end result. The multiples are the ones that tend to have different motivations, not always in the patients best interest.
I disagree when he says "eyeglasses are eyeglasses". There can be a big difference between different lenses made to the same prescription. If there wasn't then companies like Zeiss, Nikon, Rodenstock, etc,  wouldn't spend all of that R&D on developing new products when any old bit of plastic from Costco will do exactly the same job for a fraction of the price.
Yes millions are happy with their cheap, ill-fitting and poorly made glasses that may not even be made to their actual prescription. They do the job required but that does not make them the same as, for example, Zeiss iScription lenses, or Nikon aspheric lenses in a frame that fits well and has been glazed accurately.
Millions are happy with the pictures they take with their mobile phones but that does not make a mobile phone camera the same as an DSLR, or a Leica M9.
So, no, glasses are not all the same but how much difference you will notice between different lens designs I have no idea. Whether spending more money is going to be beneficial for you depends on several variables. A good independent optometrist/optician is your best bet.
Regards
Richard

[Bart_van_der_Wolf]

Where the other devices I mentioned have multiple elements, eyeglasses only have one so perhaps the error in a single lens isn't such a big deal as there isn't a cumulation of errors across multiple elements.

The multiple elements are meant to compensate for the shortcomings of a single lens, and camera lenses also attempt to achieve a flat focus plane.

I don't know as I've never worn glasses and I'm interested in knowing what people's personal experience is. I never like to rely upon one source of information, I prefer to have a few points of data before spending (what to me) is a lot of money. One would expect an optician to have accurate information but everyone has different motivations.

While money is a big motivator, most do try and fit a correct prescription for an individual. They can choose from lots of materials with specific characteristics, so they should also take the individual's specifics into consideration. Especially for eyes that have multiple deficiencies, the more expensive options do offer a rough guideline as to their quality and accuracy.

When one wants the best correction, one needs to consult a knowledgeable optometrist who also knows how to measure the correct position in the frame. I have Zeiss iScripton lenses myself, these are extremely accurate lenses (not to the usual 0.25 diopter, but to 0.01 diopter accuracy, and measured/corrected at 9 positions spread over the eye lens, not just the center. Correcting for high order aberrations allows to improve night vision as well.

Cheers,
Bart