demitri.prometheus
Oakley Expert
The only photochromic lens, I know of, that darkens inside a car is Transitions XTRActive. They darken moderately inside a car, probably to about 60% or 50% light transmission and supposedly get very dark outdoors.
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Under which conditions do photochromic lenses darken?
- Thread starter ShadedChimera
- Start date
Lumbergh
Oakley Expert
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You can buy a cheap uv flashlight at any local hardware/grocery store.
kronin323
Font of Useless Knowledge
No.
The process is from a silver halide embedded in the lenses. They start transparent to visible light, but exposure to UV causes a chemical process that changes their shape and makes them absorb visible light, so they darken. Removal of the UV source and they revert back to clear.
The reversion to clear is a thermal process, so that's why higher temps make them darken less / clear up faster.ShadedChimera
Oakley Beginner
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This has been a very informative read so far. I'm going to continue monitoring this thread to see what others say.
In the meantime, I'll be planning to write up a post around the week-old mark detailing my own experiences.Looking at your pics, it looks like to me there following are possible scenarios:
1. The lens has manufacturing defect
2. You've been standing in the shade on a cloudy day when you took those photos, or
3. The lens is approaching end of life and does not do transitions as well as it's supposed to
Bear in mind photochromic lenses have a life span of 3-5 years only, and wears out the more they perform transitions. Therefore a brand new lens may have been ex-demo in the shop for a few years and thus lead to the 3rd scenario mentioned above.
If you need testing of your lenses, take them to any good optical store as they'll have UV testing machines to demo their photochromic eyewear. Transitions would kick in within 30 seconds and by 2 minutes should reach almost its full potential. If it takes any longer then it's approaching end of life or you've got a dud kronin323
Font of Useless Knowledge
When transitions reach EOL, they start to yellow up...Here's a timing graph of Transitions VI technology of what you should expect when you test your pair under UV lamp. 1.67 SUPER SV (ASPHERIC HIGH-INDEX)
Also, bear in mind the photochromic lenses will never get as dark as something like a BI lens, but they should be darker than the pics you've posted for a full sun high UV situation.
From what I've seen, yellowing generally happen on very old lenses (around 5 year mark)ShadedChimera
Oakley Beginner
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I can say with confidence that there is no defect. I sought out a glasses shop that had a UV flashlight and asked the shopkeeper to fire it up. The lens darkened considerably, and quickly - probably because the machine's intensity was high.
This is also a brand new model; I had bought this on Sunday. So I think it was a pretty cloudy day when I took those pics.
I took the pictures on a cloudy day.Last edited:cool, mystery solved
I found my clear/black transition lenses useless in Hong Kong as there's inadequate UV to darken them significantly. Only on rare blue sky days did it darken enough to my liking. I ended up wearing VR28BI's and VR50/brown transitions to get a naturally darker tint. Whereas in Australia, the UV level is so high that even a clear/black transition can go significantly dark on overcast days.
