Proposed Lens Rating System (cacatman) (Work in Progress)

[cacatman]

Updated by cacatman 17th August, 2018

If you have suggestions to improve this classification system, please leave a comment.

Introduction
When selling sunglasses, it's often very difficult to accurately describe the state of the lenses.

There doesn't seem to be consensus as to what constitutes a 9/10 lens vs 9.5/10 vs 8/10 lens.

Personally, I would consider anything < 7/10 in quality as unwearable for long periods of time.

I would consider anything under < 4/10 to be aesthetically undisplayable.

Lens Rating System (xx.x/10)
0/10 - Cannot differentiate colour bars 10 cm wide at 6 feet e.g. black/white

1/10 - Can distinguish colours, but cannot recognise faces at 6 feet when using

2/10 - Any defect (or collection of defects) that collectively covers more than 0.5 square cm of the lens centrally

3/10 - Any defect (or collection of defects) that collectively covers more than 0.5 square cm of the lens and occur on the non-central visual areas of the lens

4/10 - More than 4 permanent visual defects per lens regardless of size which can be seen while using

5/10 - 3 permanent visual defects per lens regardless of size which can be seen while using

6/10 - 2 permanent visual defects per lens regardless of size which can be seen while using or 3 permanent visual defects which are confined to the non-central visual areas.

Scratches
- A scratch is a permanent surface marking which consists of a groove which is perceptible by running a fingernail across the edge. If one can reliably perceive the defect by fingernail alone, it is a scratch.

7/10 - Scratch on periphery of lens and can be seen during use

7.5/10 - Scratch on the periphery of lens but can be seen during use but only at extremes angles

8/10 - Scratch is on periphery of lens and cannot be seen during use viewing at extremes of viewing angle.

8.5/10 - Scratch is on periphery of lens and can't be seen from inside of lens and is < 0.5 cm in length

Swirl Marks
- A Swirl Mark is a permanent surface marking which cannot be detected by fingernail.

9/10 -

9.2/10

9.8/10 - Issue pertains to edge of lens which is not seen when lens is mounted e.g. an edge chip, scratch or dig

Lens is perfect
Yes - 10/10

Rating
10/10 - Mint condition
9.7/10 -
9/10
8/10 - Visible from inside of lens



Nomenclature
Scratches
A scratch is a marking or tearing of the polished or coated surface. The scratch designation is measured by comparing appearance with standard scratches under controlled lighting. It can be felt by running a fingernail across the surface of the lens which then "catches" on the groove made by the scratch.

Digs
A dig is a small rough spot or pit on the polished or coated optical surface, originated from defect in the raw material or from the grinding process.

Fractures and Edge Chips
Fractures which do not encroach on the clear aperture of the lens shall be allowable, given that the chips do not interfere with the sealing of the lens in the mount. Edge chips which extend into the clear aperture shall be considered as digs.

Bubble and Inclusions
Optical glass in general is nearly free of bubbles and inclusion comparing to other technical glasses due to sophisticated production process, which are optimized for low bubble content. Bubbles on pupil plan do not disturb the shape of the final image but the image contrast and brightness are reduced due to part of the light scattered. If the inclusion appears on the image plane, then the defect will show up in the final image directly, and contaminate the final image.

Bibliography
Optical Surfaces

 

[cacatman]

reserved

 

[cacatman]

reserved

 

[SEAN WAYNE]

Bro, greetings! Be best to round off the ratings. Rather than 9.8/10. A 10 is 10 no exceptions.
I have bought pairs from other collectors here too unfortunately that 9.8,9.6 /10 rating will drive buyers mad as what makes it short of a 10 is purely subjective . Just my 2 cents.
If it has scratches that impedes the line of sight that should be considered trash IMHO and should'nt even be sold as it cause more harm than good.

 

[cacatman]

Bro, greetings! Be best to round off the rating. Rather than 9.8/10. A 10 is 10 no exceptions.
I have bought pairs from other collectors here too unfortunately that 9.8,9.6 /10 rating will drive buyers mad as what makes it short of a 10 is purely subjective . Just my 2 cents.
If it has scratches that impedes the line of sight that should be considered trash IMHO.

Thanks for that @SEAN WAYNE!

But often I see people say "9.8/10" lens (just to be safe) because they want to just cover themselves in case there is a small swirl mark they missed.

9/10 implies that there are imperfections. But then, how many? and how bad? I think at the upper end of the scale, it needs to be a little more nuanced, because even if you aren't as fussy, there are a lot of collectors out there who would definitely distinguish a 9.5/10 from a 9.8/10 lens.

I have made up stuff for ratings 0/10 -> 6/10, but the reality is that few of us would use those lenses for anything. In other words, I probably should start seriously describing classification of lenses from 7/10 onwards.

 

["TRUMP"]

Bro, greetings! Be best to round off the ratings. Rather than 9.8/10. A 10 is 10 no exceptions.
I have bought pairs from other collectors here too unfortunately that 9.8,9.6 /10 rating will drive buyers mad as what makes it short of a 10 is purely subjective . Just my 2 cents.
If it has scratches that impedes the line of sight that should be considered trash IMHO and should'nt even be sold as it cause more harm than good.

Totally agree. For me, 10/10 should only be reserved for unused and unmounted lenses, or a BNIB pair that has never even been tried on. Anything else is 9/10 even if blemish free

 

[SEAN WAYNE]

First the standard of rating needs to have a passing mark. A passing mark should cover safety issues with the lenses being sold. Like scratches with a specific size that can cross the line of vision should not be allowed to be sold in the market. A 10 is a bnib ( never been mounted) . If it has a small mark then maybe a 9.5 ( not a 9.6 hehehehe).

 

[cacatman]

Totally agree. For me, 10/10 should only be reserved for unused and unmounted lenses, or a BNIB pair that has never even been tried on. Anything else is 9/10 even if blemish free

But some BNIB lenses are blemished. e.g. with inclusions. Those are not 10/10.

Mounted lenses are usually not 10/10, but sometimes they can be. Lenses are mounted in the frames at factory, so are they not 10/10?

 

["TRUMP"]

But some BNIB lenses are blemished. e.g. with inclusions. Those are not 10/10.

Mounted lenses are usually not 10/10, but sometimes they can be. Lenses are mounted in the frames at factory, so are they not 10/10?

The first thing is an exception. That's bnib w factory defects.

Mounted by factory and still in box and completely is still 10/10, anything else is less.

All this subjectivity is exactly why the best thing to do is take pics of the lenses held up to a light source. Good pics will remove most, if not all, subjectivity.

 

[htrap2294]

The first thing is an exception. That's bnib w factory defects.

Mounted by factory and still in box and completely is still 10/10, anything else is less.

All this subjectivity is exactly why the best thing to do is take pics of the lenses held up to a light source. Good pics will remove most, if not all, subjectivity.

Not just any light source, LED light only.