Ok, help me out.
We'd normally just order "variable" to make the lens design fit the frame.
However, in this case, we want a relatively short corridor in a big frame. If we order "variable", we'll get a nice long corridor.
I believe the choices for "fixed" are 11, 13, 15, 18 mm. My question: 15 mm from fitting cross to 80% of add? Certainly we're not talking a 15 mm corridor, are we?
Sell 'em a Sola XL and stop trying to save the world would ya!
;):cheers::cheers::cheers::cheers::cheers::D
Contact Matt Ballester at Rochester Optical, he's the most knowledgeable that I know of.
I was driving a Ford Pinto the last time I fit an XL, its was one of the cool ones with stripe and the "van" window in the back. Damn I miss that car..Originally Posted by Fezz
Sharpstick
Those numbers are the minimum recommended seg heights. I've been told that the corridor length is the MRSH minus 5mm.
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.
Robert, thank you.
I looked on Shamir's website, called a lab that manufactures the lens: notihing.
You had the answer.
Although I don't know for sure, I doubt that anyone would ever offer an 11mm fitting height. Those look like corridor length numbers you are quoting.
The manufacture should know what they are selling and what the numbers mean.
I'm calling the beards at Shamir.
Meanwhile, if we assume both Robert and Allen are partially correct, we'd have:
11 mm corridor + 5 mm near zone = 16 mm MFH
13 " " = 18 mm MFH
15 " " = 20 mm MFH
18 " " = 23 mm MFH
Makes sense.
From what I have been told by my Shamir rep and lab rep, the 11mm height is a 6mm channel with a full 5 mm near, at least in the variable version. They "guarantee" at least 5mm of reading in all lenses from 11mm fitting on up.
They said this short corridor is ideal for transitioning people from FT bifocals into PAL's due to the nearly non-existant intermediate.
I look forward to hearing from someone who has fit them this low to see what feedback was received.
A lack of planning on your part DOES NOT constitute an emergency on mine!
I have a pair of the 11 mm and I LOVE them !!!
I've been switching patients to these very successfully. I use the variable for +1.75 and less adds. The fixed for +2.00 and up.
A map of the differences would pique my interest.
I should have said in my post above, that mine are fitted in a P3 type frame at 25 high. There is some distortion below the main read area, but nothing serious. This is one of only 3 progressives that I have been able to adapt to as I normally wear a D-35 or a Franklin.
Rx is +.62 Add +2.25
"Jerry", technical manager at Shamir says:
11, 13, 15, 18 is the distance from the fitting cross to where the near zone is 100%.
In other words, "MFH".
He did say that the corridor length is 11, 13, 15, 18 minus 2 mm (which is corresponding minimum near zone).
So, that's that?
Shamir says the "eleven" can be fit as low as 11mm. We won't fit it that low of course.:)
I do this frequently (shorts in a deep frame). After all, if they're used primarily for reading, why would we use a long corridor design (some exceptions) regardless of the frame dimensions? As you know, you're not getting the same horizontal field with this lens compared to a segmented, but the full power is right up there where you need it- without posturing.
Yup. Must be the Jerry I talked to at 858-740-xxxx. I believe he was the one who told me the corridor length was the minimum height minus 5mm. I assumed that this was to 85% of the Add- thanks for the additional info!
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 had a regular Pinto Squire wagon - orange with fake wood. Not the cool Pinto Cruisin' Wagon.:D
DragonlensmanWV N.A.O.L.
"There is nothing patriotic about hating your government or pretending you can hate your government but love your country."
Can't find me there anymore jacqui. I now am with Shamir in the tecnical services department.
Some people see the glass as half empty, some as half full. I see the glass and wonder what the radius of curvature is.
wow !!
Those were dark times Fez... You just set my therapy back years, the flashbacks are coming in at full speed, and I am spending hours apologizing to patients until I drive home in my blue Ford Pinto Wagon (it did have the cool port hole windows in the back)
Sharpstick
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