transitions 8

I would like to know if you happened to find lenses that after activation showed this type of defectAttachment 14598

Attachment 14599

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Originally Posted by Mauro.Airoldi

I would like to know if you happened to find lenses that after activation showed this type of defectAttachment 14598

Attachment 14599

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Are you refering to the darker ring toward the outside of the lens? If these were surfaced lenses this looks like were where the edge of the wax or lead was but don't know how to fix it?

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Originally Posted by Don Gilman

Are you refering to the darker ring toward the outside of the lens? If these were surfaced lenses this looks like were where the edge of the wax or lead was but don't know how to fix it?

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These are finished lenses based on package in the pic.

My guess would be that the reflection from edge of the lens is providing a bit more UV exposure hence a pronounced ring of activation.

I'll venture it was not carefully/properly formed in manufacturing.

As I recall poly is unlike cr39. It is cast under high pressure and if not done carefully and precisely can result in distortions like this that are not readily visible in a clear lens.

Were these lenses less expensive than competitors? Just curious.

Years ago we had some great discussions over the pros and especially the cons of poly. A VP from Transitions Bob Schaeffer(?) gave us some great stories over facts and myths of plastic photochromics.

I'll see if I can find a couple as some are Hall of Fame worthy.

See Sharpsticks post #14

https://www.optiboard.com/forums/sho...ng+poly+lenses

are slow stock, transitions 8 in CR607 (like CR39)
the defect is not connected to the lateral radiation (I tried to exclude it but it does not change).
the whole stock has similar problems.
on the MR8 the thing is much less evident.
I don't understand if it is a problem only related to productions for Europe or there are similar problems also in the USA

Mauro,
The ring is caused by side activation, from stray light coming through the edge of the lens. Stray light is filtering through the unfinished edge, thus the scalloped look. If you finish the lens and put it in the frame the ring will be gone. You can test the idea by blocking the light from coming in the sides. We have taped the edged before to verify this. I have seen this effect many times.

We did some tests and contacted Transitions, in fact it is a problem related to CR39 lenses and mainly to negative lenses.
We had not noticed the problem before because we do not use CR39 in the rimmles mounts and the high indices, filtering the UV, are free from the problem. Thanks for your help

Quote:

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Originally Posted by Mauro.Airoldi

We did some tests and contacted Transitions, in fact it is a problem related to CR39 lenses and mainly to negative lenses.
We had not noticed the problem before because we do not use CR39 in the rimmles mounts and the high indices, filtering the UV, are free from the problem. Thanks for your help

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when you cut the lens the problem is fixed?

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Originally Posted by dima

when you cut the lens the problem is fixed?

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I would still try a different (more expensive?) blank and see if the problem presents in it.

Cheap lenses = cheap optics

imo

But it is the original blank made by transitions...maybe it is a defected batch?