Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Q&A

Why would a 1.74 index lens be more prone to chip and be less resilient than 1.67?

+2
−1

My optician counselled me

I don't recommend a 1.74 index with a metal grooved frame, like the one you want from ic! Berlin, because the edge will be less resilient and be more susceptible to chipping.

Please explain like I'm 5 years old. I don't know physics or opticianry. Why's 1.74 more brittle? Why does "chipping along the groove" mean? What does "thinning" mean?

Think of lenses as having 4 levels of thinning; Basic 1.49, 1.59/1.60, 1.66/7, and 1.74.

Why would 1.74 be too fragile? Why a lot of stress on the lenses for metal groove frames like those?

1.74 will most likely chip and break especially along the edges of the groove.

My optometrist, different person, diagnosed me with nearsightedness. His prescription shows

OD –6.00 (Sphere), –1 (Cylinder).
OS –7.00, –1.

History
Why does this post require moderator attention?
You might want to add some details to your flag.
Why should this post be closed?

1 comment thread

General comments (2 comments)

1 answer

+2
−0

To be optically equivalent, the lens made from lower index of refraction material needs to be thicker.

My guess is that your optician thinks the metal grooved frames you want won't work well with the outer thickness of the lenses. Note that he's not saying 1.74 index is bad, but just that it's somewhat incompatible with the particular frames you have chosen.

-7 and even -6 is rather extreme. This limits other tradeoffs.

History
Why does this post require moderator attention?
You might want to add some details to your flag.

0 comment threads

Sign up to answer this question »