I just noticed they are also etching what appears to be a small "QR code" onto the temple edge on regular Single vision A/R coated jobs as well.
FYI, I ordered a smartlife individual 1.67 with duravision platinum last week and requested no branding, and received today without branding !
I dispense hundreds of Zeiss lenses every month, all of which have the Zeiss logo in the corner, all of which come out in exactly the right place (since we specify the exact shape), all of which have AR (because why would you not have Duravision Platinum) and have not had a single customer complain.
It's such a nice finishing touch, as well as a guarantee of quality. I really don't understand the problem.
Maybe it's a regional thing?
Interesting. I've literally never has a Zeiss lens give me a "WOW" effect. Except for their camera glass - in particular their cost! I found their PALS to be pretty average when I used them (probably been 6 years back now mind you), but their top AR would craze in a stiff breeze. Not sure if they ever fixed that or not. And at least at the time, their lab bills were pretty crazy as well. Either that, or the local E lab was somehow able to give us a rockin price list to compete. *shrug* I'd like to see something truly innovative and that lasts (no scratching/crazing). Might try again some day...
Pop quiz, hotshots. Say we order a Zeiss SV Individual and specify fitting height of 20 and panto of zero. The OC height produced will be A) 20, B) between 16 and 17. SPOILER ALERT: The lenses we got back are B, not A ???
Zeiss Individual SV is positioned with the pupil 4mm above the prismatic centre so it sounds like they were made correctly. You should glaze them like a progressive with a drop of 4mm.
they always use prism thinning like that
The lenses are fully optimised so I really wouldn't worry about it. I think Zeiss know what they are doing.
I would hope lensgrinder can comment on this.
No direct relationship because the software (when POW capable) corrects for any misalignment of the lens and visual optical axes. The 4mm 'drop' reduces lens thickness by aligning the PRP closer to the 180 line.
That's one of the advantages of POW optimized free form surfacing: 15˚ of panto tilt on a zero drop Seiko PAL and the software corrects the power error and oblique astigmatism at most/all angles of gaze.
Best regards,
Robert Martellaro
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
I'm at the level of AK47, here. I would like to know.
Also, I was just told that face form angle data is warehoused by Zeiss labs on most frames, and that we get "free" face-form optimization on all the Precision series lenses. Is that true?
Grandpappy Robert, are you saying, in a non-mansplainy way, that
--"back in the bad old days, if you wanted to minimize (some kind of) errors (from some eye's center of rotation alignment with the optical axis of the lens or whatsmajiggit when in downgaze), you had no choice other than to lower the optical center of the lens 1mm per degree of pantoscopic tilt..."
--"now in these newfangled ages with these computeees, they can put the optical center of the lens nice and low to keep that lens thin as a hungry mudpuppy, but surface the optics such that the patient views through a point in the lens that is optimized for straight ahead and down gaze (and maybe lateral gaze but maybe not because of limited face-form frame options)??????
In other words, are you saying they can "disassociate" the optical center with the "optimal spot" for optics?
Last edited by drk; 09-22-2020 at 09:46 PM.
Yes sonny, you are absolutely correct, except for the bold part where the relationship is .5mm per 1˚ of pantoscopic tilt.
I do get some relatively simple PAL Rxs on occasion. When their POW values look close to default, I'll use a non-POW capable lens to save my client a few bucks, if the fundamental PAL design is appropriate for their needs. (I charge for the extra time/work/expertise for POW measurements in addition to the increase in lens price).
Note: most dumb and smart PALs start out with default values of about 5˚ and 8˚ for the wrap and panto tilt respectively, and 13mm for vertex distance. There is significantly more aberration that can be corrected when the tilt values are larger than the default values, as opposed to lower values. Any large deviation in vertex distance should also trigger a decision to use POW optimized PALs.
Best regards,
Robert Martellaro
Last edited by Robert Martellaro; 09-22-2020 at 03:04 PM.
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
Thanks for the reply.
I think I get the point, but I don't understand how they do such things.
Your welcome. I like the familylike atmosphere here.
See: https://www.optiboard.com/forums/sho...l=1#post418640
Robert
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
Here's the white paper referenced in the above link.
https://www.zeiss.co.uk/content/dam/...aper_15630.pdf
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
That was a nice read. He really did a good job balancing meaty optical physics with understandable language for the rest of us.
One thing he chose not to dicuss was "why tilt a lens, in the first place?".
Here's how I understand it, and see if you concur:
The eye rotates as we go about seeing stuff, and mostly up and down. If the lens wasn't tilted with panto, it would be farther away from the eye in downgaze, and the optics would be different.
So, we tilt the lens in closer at the bottom but then that screws up the powers in straight-ahead gaze somewhat (and it really messes up the top, but who cares?).
So to compensate that, we drop the optical center a little. Now, I'm not sure what this achieves.
So, in other words we're trying to average out or split the difference between straight-ahead gaze and downgaze (and we are ignoring side-gaze and up gaze).
Soooo...with custom optics, we can just zap the correct powers anywhere on the old lens that we want. (Maybe I should look at Brent's Tscherning Ellipse for near vision, too.) Is this correct?
Heck, it occurs to me (as in the post above) that we can have zero panto all the time, if we wanted it. (But then we'd get some reflection issues, I'd think. Mostly, zero panto is from fat cheeks and/or big eyesize.)
Last edited by drk; 09-23-2020 at 09:49 AM.
My books are at the office, so from memory:
1) Our eyes/orbits are angled down slightly, maybe so that our ancestors didn't walk over cliffs!
2) We tend to lower our gaze when focusing on near objects.
3) Minimize vertex distance on the downgaze.
4) Facial bone structure generally protrudes at the brow as opposed to the cheek.
It aligns the optical axis of the lens with the center of rotation of the eye (see image below).Here's how I understand it, and see if you concur:
The eye rotates as we go about seeing stuff, and mostly up and down. If the lens wasn't tilted with panto, it would be farther away from the eye in downgaze, and the optics would be different.
So, we tilt the lens in closer at the bottom but then that screws up the powers in straight-ahead gaze somewhat (and it really messes up the top, but who cares?).
So to compensate that, we drop the optical center a little. Now, I'm not sure what this achieves.
Best regards,
Robert Martellaro
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
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 since a free form lens lacks an optical center.
Although the rule of thumb is to lower the optical center 0.5mm per 1º of tilt in a spherical or toric lens, more is taken into account with a free form SV and the point from which the distribution starts is based on wrap, tilt, center of rotation distance, and other criteria.
You can look at a map with the same power, material and thickness, but with different PoW and you will notice a different distribution of power.
All ZEISS free form lenses are compensated based on default PoW measurements, this includes free form SV, Digital(anti-fatigue) and Office lenses.
Last edited by lensgrinder; 09-28-2020 at 08:27 AM. Reason: Added content
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 I get 20 degrees of wrap compensation?
Or, do I have to move up to the Superb to specify?
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