If you put 2 lenses on a table, same index,thickness,coatings and rx, say 1 is a physio 360, 1 is an ipseo. The markings are not visible or at least the lens is not marked with the usual indicators, could you tell them apart? You may use any optical lab equipment at your disposal. Substitute ipseo or physio for any 2 similarly produced lenses (say 2 different backside "hd" lenses).
Welcome to Optiboard, optimensch!
Not from a table per se, I would have to hold them up and look through them preferably with graph paper in the background and move them back and forth. Would that suffice? The table is too close and textured and doesn't allow the ability disern much. Its like holding your hand 1 inch from your face and asking someone to read your finger prints.
Being able to tell the difference would depend on the lenses, many of the T-shape Free-form designs look very similar and are difficult to discern from each other. Some other lenses are more distinct in their patterns and stand out like the Multigressiv, Definity, Hoya ID's, Seiko Surmount or Zeiss GT2-3D. The Shamir Auto II and Zeiss Individual will look very similar through graph paper though as they have very similar pattern, but I have not looked through enough Zeiss individuals to see the pattern in every Rx. I could miss that lens in a lot of cases.
Wearing them in the same RX though is the best way, I can tell intimate difference between designs and recognize most designs clearly.
I just tried a design 2 weeks ago out of Europe and I guessed right away that someone had left Rodenstock and gone to work for their design team. They were agast but they could neither confirm nor deny that I was correct . There were a lot of similarities in style to Rodenstock's though.
Thanks sharpstick, actually I don't know why I specified a table. Really a table has nothing at all to do with anything. Basically just wanted to know if you could differentiate designs from each other without simply relying on markings. That is an impressive skill.
HI sharpstick, i asking a question which is out of the main topic here.. you have mention 'many of the T-shape Free-form designs look....' may i know what is T-shape Free-form about? perhaps you have any other link can direct for my personal reference?
thank you.
Yeap
A T-Shape design is generally clearer across the 180 and emphasizes distance fields of view only. It will also in general have a softer and narrower intermediate and reading (the bottom part of the T) and in many cases will have reading narrower than some grinders. There are a couple harder T shapes but they will have more geometric or spacial distortions along with their wider corridor.Originally Posted by Yeap
Its a term designers and engineers use, its has not made it out into the world until now.
I just took a piece of graph paper, put 2 very sharp and straight extra lines through it with a technical pen, and then laminated it. Then I with every lens I ordered I held it over the graph paper and moved it around over the paper at final inspection, I was doing this for about a 100 progressives a week for years. Its not as good or scientific as lens mapping but a lot cheaper. If you do this you will figure out what lenses do to the light as it goes through them.
Tried with your method, but failed to tell. Am I missing something?
Pull the lens far enough away until everything starts to get blurry, and then close in a bit. Look at the shape change in the squares and where the lines get blurry as you move the lens around. The blurry will tell you where the junk is; the shape changes will tell you how and where the lens manages unwanted cyl and geometric distortions as the squares turn into trapezoids, and then get blurry.
Where the lines break and get blurry will tell you how and where the distortion is. Line breaks or squiggles are the worst thing that can happen. All progressives will bend light and lines its just a matter of where and how they do it. Nothing will scream at you, its all very very subtle. Try a grinder with a high plus and a high add and you will see what I mean faster.
Also, stay focused on one line through the lens, move it up and down and then watch how one line behaves (that is why I darken 2 in a crosss with a techical pen). Does it bend? At what point? You can do this with any straight line on a wall or eve ceiling tiles.
Last edited by sharpstick777; 04-05-2012 at 11:23 AM.
The Ipseo is a dual add design (add on the convex and concave side.) the Physio 360 has all it's add on the convex side (digitally surfaced). You can use a lens clock to confirm part of the add is on the back of one of your lenses (the Ipseo). I've still not developed Rotlex eyes like sharpstick.
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