Ditto but make sure it's aspheric and ground digitallyOriginally Posted by kcount
Ditto but make sure it's aspheric and ground digitally
Mike,
I believe Zeiss 1.732 (1.74) is done aspherically on BOTH side in Germany.
FWIW
B
Barry, where do you see the advantage in double aspheric as compared to real time design individually optimized (ray tracing corrected) lens? Also, I am not sure, but I believe the ABBE on 1.732 (1.74) is 33, 1.71 it is 36; less longtitudinal aberration particularly of significance on higher powers. I would be really curious on the patient response to both; next time you get some strong Rx I would like to make you a pair gratis just to compare.
I know that ABBE was a big concern to me when I was a -15. Now if you could do all that fancy stuff to 1.70 product, you again would have a very small difference in thickness, but better vision. I tried 1.67 once and had to practically put a neck brace on so I wouldn't move my eyes too far from OC. So for years (until 1.70) I used Spectralite even though I could get thinner lenses, I could not stand the poorer optics.I imagine the 1.74 would have been the same.
Now it's not a problem since my worst eye is a -1.50.
DragonlensmanWV N.A.O.L.
"There is nothing patriotic about hating your government or pretending you can hate your government but love your country."
I',m thinking your experience was before fully optimized free form. Yes, abbe is an issue, but is often blamed all on abbe, when the "optics" may have been much less than optimal in that recipe as well.
B
working two surface in lens design is always better than one. Period.
I relie upon Zeiss's optimization algorythm to do its best. In minus...even at these powers and up to a 58 eyeaize (yes!) I have very satisfied Individual 1.743 wearers. Plus, well, I think after 6D abbe is a real issue. Why plus more than minus I cannot speculate as to the reason, but that is my experience.
B
I tried many times to get optimized free form lenses. Problem is, no one had points files that were strong enough. Poor Allen at ICE-TECH tried for six months to make me a pair, but all he got out if it were bad lenses and a broken diamond. I would have loved it if anyone had been able to do it for me, as I would have definitely gotten them. Then I tried 1.70 Hoya ECP progressives, and, though not freeform, the vision was nearly as clear as Spectralite (still saw some color fringeing) and the lenses were a lot thinner. Then came my unfortunate experience with 1.67.
BTW, I really love my Zeiss Individuals.
DragonlensmanWV N.A.O.L.
"There is nothing patriotic about hating your government or pretending you can hate your government but love your country."
I remember something that Darryl Meister said awhile back during a OB discussion on the advantages of splitting the Add power between the front and back surface, and his response was something like- what can be done on two surfaces can essentially be done on one. I did some digging on the Definity patent and discovered that the claimed reduction in unwanted surface astigmatism was about an insignificant 5% compared to an identical design on one surface. No other claims were made to the best of my recollection.
Working the surface with the most curvature will return the greatest optical and cosmetic benefit. After all, how much can you modify a +1.00 front on a -13.00 or a -1.00 back curve on a +13.00?
They were probably wearing non-optimized 1.67, which has a similar Abbe to 1.74. Moreover, it's unlikely they were as well positioned as what you provide. That, combined with (potentially) significant reduction in oblique astigmatism and/or RMS power error, along with POW, and other optimizations (Zeiss does this as well as anyone), can result in noticeably improved on and off-axis vision.In minus...even at these powers and up to a 58 eyeaize (yes!) I have very satisfied Individual 1.743 wearers.
With regards to Michael's point, how much reduction in TCA occurs 15mm off-axis, on a 13.00 D lens, between 1.71 or 1.70 and 1.74? I get .05^ (13 x 1.50/36 = .54^ and 13 x 1.5/33 = .59^), probably an insignificant amount for most eyes/brains, all other things equal. However, switching to 1.60 decreases TCA to .46^, possibly improving acuity by one whole line. The next question that one needs to ask is how much time does the SV lens wearer spend looking 15mm off-axis? Certainly less than a multifocal wearer, where the near gaze is 10mm to 15mm off-axis. I suspect that single vision wearers would respond by saying that the lens might feel slightly more refined, but not clearer per se.
Maybe because the myope requires less ocular rotation to see an object in their field of vision compared to a hyperope, due to magnification and minification?Plus, well, I think after 6D abbe is a real issue. Why plus more than minus I cannot speculate as to the reason, but that is my experience.
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 remember something that Darryl Meister said awhile back during a OB discussion on the advantages of splitting the Add power between the front and back surface, and his response was something like- what can be done on two surfaces can essentially be done on one. I did some digging on the Definity patent and discovered that the claimed reduction in unwanted surface astigmatism was about an insignificant 5% compared to an identical design on one surface. No other claims were made to the best of my recollection.
I was speaking specifically to SV lenses, and not progressive adds. I think the dual aspheric design of Individual SV does improve overall off-axis correction.
Working the surface with the most curvature will return the greatest optical and cosmetic benefit. After all, how much can you modify a +1.00 front on a -13.00 or a -1.00 back curve on a +13.00?
They were probably wearing non-optimized 1.67, which has a similar Abbe to 1.74. Moreover, it's unlikely they were as well positioned as what you provide. That, combined with (potentially) significant reduction in oblique astigmatism and/or RMS power error, along with POW, and other optimizations (Zeiss does this as well as anyone), can result in noticeably improved on and off-axis vision.
Yes!
With regards to Michael's point, how much reduction in TCA occurs 15mm off-axis, on a 13.00 D lens, between 1.71 or 1.70 and 1.74? I get .05^ (13 x 1.50/36 = .54^ and 13 x 1.5/33 = .59^), probably an insignificant amount for most eyes/brains, all other things equal. However, switching to 1.60 decreases TCA to .46^, possibly improving acuity by one whole line. The next question that one needs to ask is how much time does the SV lens wearer spend looking 15mm off-axis? Certainly less than a multifocal wearer, where the near gaze is 10mm to 15mm off-axis. I suspect that single vision wearers would respond by saying that the lens might feel slightly more refined, but not clearer per se.
Agreed!
Maybe because the myope requires less ocular rotation to see an object in their field of vision compared to a hyperope, due to magnification and minification?
Robert, as always, yours is the best explanation yet!
Robert is one of my favorite mavens here on optiboard!
B
"working two surface in lens design is always better than one. Period." Quite blatant statement. I wonder where it is coming from? You can't be thinking of Real Time Design Individualized Lens Technology, are you? As Buddha said:"Believe nothing,
no matter where you read it
or who has said it,
not even if i have said it,
unless it agrees with your own reason
and your own common sense."
Mike,
My experience behind that statement comes from telescope and eyepiece design, and from a company that I advised and worked with for over 25 years, Tele Vue Optics. The owner was an optical engineer/designer, and holds many patents in lens design. He tutored me. And I can tell you, the *only* reason the best camera lenses have so many elements (individual lenses) is to optimize the color, field, and off axis properties for the intended use. Now with ophthalmic lenses, the CR of the eye, the far point sphere and the typical POW values can dictate or limit just what can be done with either one or two surfaces. But remember that in SV design, without the need to deal with variable surface power (progressive), two surfaces can and, in the right optimization, do help deliver superior off axis vision.
The amount of improvement possible this way over using one surface is really the only debatable question.
B
Hi,
I can only find up to 1.67 on the Zeiss website. Could you kindly provide some additional info on the 1.732?
I am a -12.00 and am trying to make up my mind between Zeiss Individual SV and Rodenstock Impression Mono. Both seem to be avaliable only up to 1.67 unlike their progressive counterparts
TIA
giulio
Zeiss calls it Individual 1.74, either SV or progressive
B
Many thanks, Barry!
giulio
agree with you
I see it with Premium w/view protect, but never on SHV.
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