High refractive index glasses - thoughts

[Dave-P]

One for the glasses wearers - just wondering if anyone had any opinions regarding whether thinned (high RI) glasses lenses made seeing easier or worse at the  eyepiece?

Edited February 12, 2023 by Dave-P
General illiteracy

[pipnina]

I don't know about eyepieces, but when i took up the option for lens thinning years ago my vision was plagued by chromatic abberation even slightly off center. Never taken that option since despite my Professor Farnsworth thick lenses.

[Carbon Brush]

It all depends on the lens. Not all lenses are created equal😁

I have used high dioptre, then high RI when available, lenses all my life.

Some have made good spectrometers, others have been definte ED refractor quality.

Fortunately most high street opticians do a 30 days refund/reglaze type of service.
Ask the awkward questions - don't just accept one recommendation.
If you don't get the answers to questions, use a different optician.

If you can get access to the books some opticians keep in the back, or under counter, you get answers.
The lens manufacturers catalogue of blanks shows not only RI, but variance with wavelength.
Another important one for those of us 'of a certain age' is how a varifocal transistions.
There are images that look like contour maps.
Some lenses have a tiny reading region so you have to move your head almost at every word on a line.
Other have a large reading are.

HTH, David.

[Carbon Brush]

I know that I have used a particular Zeiss varifocal lens for some years, and had good results.
So I thought I would take a look at the Zeiss UK site for data, to help with the enquiry.
Unfortunately the Zeiss site only shows 'glossy leaflet' type of minimal information. OK I really mean it is next to useless.
Us uneducated peasants are locked out of the useful pages.

Reminiscent of when I asked (as an industry professional) about the contents of their lens cleaner and they wouldn't play ball.
That information is only available to industry users.....
But I am an industry user. Look at my email domain. Look up the company on the web site......
In this case we decided to not buy the Zeiss product and went for something we could identify.

On my next visit to the optician I will try to grab photos of relevant pages.

[AstroKeith]

I used to by very myopic, before cataract replacement surgery. I had a pair of high RI spectacles, and the CA was very noticeable. After discussion with my optician they made some astronomy dedicated specs with quality glass. They weren't very attractive but they worked well.

Although I now only have astigmatism and reading to correct, I have continued the practice of having a dedicated pair of glass spectacles. When I put my 'normal' spectacles on for night work I can see issues. This may be more to do with the complicated zonal correction going on than the RI of the material. My 'normal' specs are top of the range Hoya.

[Dave-P]

I currently wear bifocals (not a fan of varifocals, to me they  seem designed to make your eyes lazy, the middle prescription just made me feel mildly drunk), so I've got to be careful to keep the lower pane out of the way when approaching the eyepiece. Have fairly heavy brows, so was going to look for a pair of smaller frames with single vision optics where the lens fits closer to the eyeball to maximise eye relief. Guess I need to phone round the local opticians to see if any do specialist glasswear. Have a sinking feeling that they're mainly chains/franchises who do "standard" and various flavours of "thinner". It would be good to find one who was properly into their optics.

Thanks folks.

[Ratlet]

Fun fact:

If you want some fancy thinned lenses but don't want to spend big fish on the premium, ask your optician to put in polycarbonate lenses (safety spec glass)

It's as thin as some of the thinnest lenses but can be got for free of the NHS.  No coatings on them unfortunately, but good for the price.

I did this for years as I combined being broke with my innate Scottish grippyness.  -8.5 in each eye so my lenses are beefy.

[bosun21]

On 15/02/2023 at 16:57, Carbon Brush said:

Reminiscent of when I asked (as an industry professional) about the contents of their lens cleaner and they wouldn't play ball.

There you go Dave 👇

[Astrobits]

If you want the breakdown of a product then google the product name and MSDS ( Material Safety Data Sheet).

Note that the "Zeiss lens cleaner" and "Zeiss lens cleaning spray"are different products with different ingredients.  The former is just 5% Isopropyl Alcohol in Water.

Nigel