# Activity Stream

• 09-29-2020, 03:43 PM
Yup, Prentice's rule is not dead-on balls accurate for oblique angles of view, and certainly doesn't take into account higher orders of aberration...
8 replies | 151 view(s)
• 09-29-2020, 03:01 PM
Oh I love these sort of discussions! Mostly because I always learn cool new facts and tricks - but also cause it shreds the poly haters...with...
8 replies | 151 view(s)
• 09-29-2020, 02:54 PM
Thank you.
100 replies | 9125 view(s)
• 09-29-2020, 02:09 PM
The formulas remain the same: TCA = P/v The difference is in how you determine prism amount. Using Prentice's rule you do not take the the angle...
8 replies | 151 view(s)
• 09-29-2020, 12:13 PM
Brent, The formulas I've seen make no mention of thickness, but then at our level (ophthalmic dispensing) .01∆ of Transverse Chromatic Aberration...
8 replies | 151 view(s)
• 09-29-2020, 11:15 AM
As the thickness increases the prism amount increases thereby increasing the transverse chromatic aberration viewed by the wearer. The prism looking...
8 replies | 151 view(s)
• 09-29-2020, 10:04 AM
I'm not aware of any direct correlation between thickness and dispersion, at least with ophthalmic lenses. Generally, higher refractive index...
8 replies | 151 view(s)
• 09-29-2020, 09:37 AM
You would have to use a Superb or Individual to specify PoW. You could also use one of the Sport options if the base curve is steep enough.
100 replies | 9125 view(s)
• 09-29-2020, 09:35 AM
You can approximate the transverse chromatic aberration(TCA) by calculating where you want to calculate the TCA. For example you could calculate a...
8 replies | 151 view(s)
• 4 replies | 199 view(s)
• 09-29-2020, 08:49 AM
Ok, thanks for answering. Let me be explicit...If I'm ordering a Pure (which doesn't have a face-form option) for a 20 degree wrap sunglass, will...
100 replies | 9125 view(s)
• 09-29-2020, 08:42 AM
FACT: The refractive effect of the material on the central wavelengths (yellow colors) is the same in principle (though not degree, due to energy...
8 replies | 151 view(s)
• 09-29-2020, 08:36 AM
Very nice work. Congrats on the custom job.
1 replies | 97 view(s)
• 09-29-2020, 02:19 AM
Hi, We know that on paper ABBE number describes amount of dispersion. But this is not inherited property of a real lens - in a real lens, in order...
8 replies | 151 view(s)
• 09-28-2020, 06:46 PM
After years of tinkering and a lot of trial and error, I finally put together my first real in-house custom clip for a patient. I developed a...
1 replies | 97 view(s)
• 09-28-2020, 03:23 PM
You're learning, DrK!
4 replies | 199 view(s)
• 09-28-2020, 11:10 AM
I've never dealt with one but I would lean toward edging them like the old Zyloware nylon Invisible. Undercut it a half millimeter or so for a no...
7 replies | 317 view(s)
• 09-28-2020, 08:26 AM
The PRP location serves as a reference point to check power and prism. This point does not necessarily represent the optical center of the lens...
100 replies | 9125 view(s)
• 09-28-2020, 07:14 AM
Robert and lensman are right above. At least that's what I always thought I knew.
16 replies | 839 view(s)
• 09-27-2020, 05:05 PM
It's a Beautiful Day - White Bird 1970 Escape from doomscrolling and apocalypse prepping. Heroin optional.
1291 replies | 450756 view(s)
• 09-26-2020, 11:05 PM
Destructive interference. Where does the cancelled energy go? Through the lens, increasing light transmission, satisfying the conservation of energy...
16 replies | 839 view(s)
• 09-26-2020, 08:17 PM
Your physics professor is partially correct. Let's say that in a perfect environment, physics will hold true regarding the throughput of light in...
16 replies | 839 view(s)
• 09-26-2020, 03:59 PM
They indeed react to visible light but not the the full spectrum. They do not activate to their full potential in a car because the uv is blocked. If...
16 replies | 839 view(s)
• 09-26-2020, 03:40 PM
With regard to XTRActive, you are incorrect. XTRActive is activated by both UV and visible light, as per this PDF from transitions.com: ...
16 replies | 839 view(s)
• 09-26-2020, 02:15 PM
Remember Transitions is activated by UV not visible light. Most materials block uv except cr and many AR coating are formulated to do the same. So...
16 replies | 839 view(s)
• 09-26-2020, 01:36 PM
Well, the best way to settle this is to have a fixed, lab quality full spectrum light source, measure it with a calibrated visible light photometer...
16 replies | 839 view(s)
• 09-26-2020, 01:04 PM
That's really interesting. But, it can't be true, or there wouldn't be an advantage to ARC on camera lenses, or microscope lenses etc... because if...
16 replies | 839 view(s)
• 09-26-2020, 12:59 PM
I had a physics professor prove to me that antireflective coatings do not allow more light pass through a lens. I will admit I really didn't fully...
16 replies | 839 view(s)
• 09-26-2020, 08:20 AM
DaveR replied to a thread Edging Person Needed! in The Job Board
Good Morning Michael, Just saw this and am hoping the position is still available. I sent my resume to the above email. Hope to hear from you. Dave...
1 replies | 657 view(s)
• 09-25-2020, 04:58 PM
Hello, I am interested in your position. With over 30+ years as an Optician and various high corporate position in the Opticsl field, I would be an...
5 replies | 759 view(s)
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