Hi guys and gals! :)
Is there a difference in "Digitized" and "Free Form" lenses?
Hi guys and gals! :)
Is there a difference in "Digitized" and "Free Form" lenses?
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A good question Heather. The answer is: Yes. And No.
Confused?
Good.
OK, so there isn't yet any really good consistent means that every lens company uses to describe their lens designs. Some say one - some say the other. And some use only 'partially' digital designs.
The best answer I can probably offer - is simply to ask your individual lens manufactuers you're currently using. You can also ask the lab as well, and they should be able to tell you with a high degree of accuracy the level of 'digitalness' of a given lens. :)
Cheers! :cheers::cheers:
Brian~
Heather,
Its subjective... and Shamir owns the rights to the term "Freeform" now (although Zeiss and Rodenstock were using the term in the 1990's) so it may be just for legal reasons the terms have become interchangeable.
Without the legal thing... I would consider a traditonal cast progressive with backside (but non-optomized) digital processing to be "Digitized". I would consider a lens that at least adjusted the atoric curvature for a better wearer experience to be "Freeform". Many newer "Freeform" lenses however take into consideration such things as seg height, add power, vertex distance, pantoscopic tilt, face form etc.
Generally "Freeform"refers to the design and "digital" refers to a way lenses are made with a rotating lathe instead of grinding.
I take an old crappy design and digitize it (the Adaptar 360) for example but I cannot grind a freeform design.
Heather- Check out Tonys site and bookmark it if you haven't already.
On the home page you can click Search Pages click Digital Surfaced.
Read his definition of differences on the top of the page below:
http://www.thelensguru.com/digitalChart.php
Freeform has been corrupted by too many manufacturers to have a consistent meaning anymore imho.
Last edited by Uncle Fester; 05-01-2009 at 04:08 PM. Reason: tweak...
Thanks for the replies everyone...I'll check out Tony's site...it's bookmarked, but I never thought to look for info on this.
Thanks again, I appreciate it! :)
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Calling Laurie Pierce!!! Laurie to the front desk!!!!!!!!!!
The reason this subject is so misunderstood is that the marketing of lenses has caused terms that were designated to mean one thing, used to try to make a lesser product now seem to be better.
Multi-axis CNC machines made by Schneider (such as their Master), SatisLoh (such as their Orbit), Opto-Tech and DAC to name a few, are designed to cut this diffenent surfaces that could not be cut years ago.
The facts are that if a lens is cut on a multi axis CNC machine designed to be able to cut a surface with almost any design, then this machine can cut a very advanced individualized design or it can be used to cut a lens with the same curves that have been cut on the back of that lens before this new equipment was available.
The real benefit is a combination of software, lens designs and equipment designed to optimize the surface to yield a field of better vision.
If you would like more information just add to the post or send me a PM.
That's not an entirely true statement. The Gerber SG-8 was capable of cutting all the same surfaces as the newer equipment...we had special test software where we cut backside progressives in the early 1990's. What has changed is the polishing technology. Polishing technology has been aided by much better surface smoothness of the newer generators ("well ground is half polished"). But the trick was to figure out how to polish the lenses, not grind them. CNC machining was a fairly mature science even in the dark ages of the 1990's.Multi-axis CNC machines made by Schneider (such as their Master), SatisLoh (such as their Orbit), Opto-Tech and DAC to name a few, are designed to cut this diffenent surfaces that could not be cut years ago.
By that definition, lenses produced off CNC machines like the Gerber SG8, Coburn IQ-Lathe, etc. were "digital". I personally agree with that defintion. But remember, as has been said many times on Optiboard, the method of product and the design are vastly different notions.
Generally "Freeform"refers to the design and "digital" refers to a way lenses are made with a rotating lathe instead of grinding.
RT
Terms such as "digital" surfacing and "direct" surfacing are synonyms for "free-form" surfacing. I believe that Essilor originaly coined the phrase "digital" surfacing, although the actual machines are generally referred to by the equipment manufacturers as "free-form" generators, since they are capable of producing "free-form" surfaces that lack point, axial, and plane symmetry.Is there a difference in "Digitized" and "Free Form" lenses?
While the SG-8 could replicate the basic surface geometry, the surface roughness is pretty significant for soft lap polishing. I suspect that polishing the surface to a high luster with a soft lap tool could result in significant form errors over the surface. Has this been your experience? Are the encoders and actuators of the SG-8 accurate enough, and the controller bandwidth high enough, to handle rapidly varying progressive lens surfaces?The Gerber SG-8 was capable of cutting all the same surfaces as the newer equipment
Darryl J. Meister, ABOM
RT, Please do not add more confusion for those trying to understand digital surfacing and/or freeform.
Although I do not know all of the inner workings of the machines you mentioned. I do know motion control and the ability to control the surfaces requires much more precision than was capable in previous machines. You could not cut a backside progressive with the cutting tools used in these older machines, the resolution of the encoders were not nearly good enough, etc. etc. It was a lot more than the polishing.
The lenses produced on those machines were designed and used to make spherical cuts, not complex surfaces. (even though the motion control may have had more capabilities, the total machine design did not).
True precision CNC machines and the capabilities necessary to produce these surfaces ARE NOT THE SAME,as the machines you mentioned.
Your statement is like saying A VW bug from the 60's that has 4 tires and a steering has the same performance as a modern day Formula 1 car. They both have 4 tires and a steering wheel, therefore they are the same.
I was trying to add less confusion for optiboarder not more.
There were 2 impediments to using SG-8 era CNC machines for backside progressives, and neither were related to controller bandwith or encoder accuracy. One impediment was the relative surface roughness, which is not to be confused with accuracy. As you note, the surface roughness was pretty significant for going "direct-to-polish", and other polishing methods just didn't work. But remember, roughness and accuracy are not identical...take a lens off a well calibrated SG8, fine it for 5 seconds, and you have a smooth lens. But polishing isn't designed to remove material in that manner.While the SG-8 could replicate the basic surface geometry, the surface roughness is pretty significant for soft lap polishing. I suspect that polishing the surface to a high luster with a soft lap tool could result in significant form errors over the surface. Has this been your experience? Are the encoders and actuators of the SG-8 accurate enough, and the controller bandwidth high enough, to handle rapidly varying progressive lens surfaces?
The second impediment was the relative lack of computing power and know-how to calculate the toolpaths. It wasn't so much a matter of not being able to cut a complex surface, it was the problem of knowing which complex surface to cut! Ironically, that's not much different than our current problem with our nomenclature...we want to use "freeform" or "digitally surfaced" to imply something very high tech about the design, yet "freeform" and "digitally surfaced" merely imply something about how it was made. One could use an arbitrarily expensive freeform generator to make an arbitrarily complex surface...that wouldn't correct anybody's vision.
RT
Very well stated.we want to use "freeform" or "digitally surfaced" to imply something very high tech about the design, yet "freeform" and "digitally surfaced" merely imply something about how it was made. One could use an arbitrarily expensive freeform generator to make an arbitrarily complex surface...that wouldn't correct anybody's vision.
Darryl J. Meister, ABOM
Darryl, it might be helpful to those who originally created and responded to this thread if you attached the article you wrote on the subject that you already attached a while back. (Some may not have seen it and as freeform and digitally surfaced are now of more interest to a wider range of those in the industry).
We kindof got off course to the original topic asked.
Yeah, sorry, we did get off the thread. Actually, the most succinct answer to the original question was touched on by Darryl: The diffference between "freeform" and "digitally surfaced" is that the term "digitally surfaced" was coined by one company because of questions over the trademark status of "FreeForm" (note the capitalization when referring to the registered trademark usage).
In general use, the two terms are equivalent.
RT
These various terms were coined to create confusion. The first to market with the technology wins, what did they call it? This is the term that should be used everyone else is just coining their own term for something that has already been implemented.
Design has always been the key to a good progressive, various manufacturers have flip flopped on that concept throughout the past few years going from everything digital or free form is far more superior to now saying the design makes the difference and even a traditionally molded good design is far better than a poorly designed free form product.
To date their is no subjective metric to determine which designs by which companies are going to be better than others, so we're left to trust our own instincts, anecdotal evidence, and marketing literature. I tend to trust my instincts when it comes to these things. I try to use products from companies that have in the past shown integrity in their designs. I would much rather trust a company that has put out one design that is quality than a company that puts out one design a year, often the one design a year will end up with slight improvements yet the cost will be high for that slight improvement. In the FF products I like the Shamir products and use them when necessary, I have used definity in the past, but stopped since their is very little information available about their design. I am waiting to try the Zeiss products but to date I have heard of a few issues with the time lien to get the product, again no doubt due to the insistence on quality over quantity.
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So all dispensaries that include a one-hour surfacing lab should be called "Lenscrafters"?This is the term that should be used everyone else is just coining their own term for something that has already been implemented.
RT
Digital is the conversion of information to binary numeric form. Almost all of our equipment communicates in the digital domain.
FreeForm (surfacing) is a manufacturing process that is capable of creating very complex (or very simple) lens designs directly to the surface.
However, it's the software that determines the type of surface and its degree of complexity, hence the products final characteristics. In art terms, the FreeForm generator is the brush, the lens is the canvas, and the software (the one who writes it) is the artist.
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.
Really, that's not even a realistic comparison. Lenscrafters is the name of the company not a process or product. Although you'll see many stores with in house labs use the phrase "glasses in about an hour" it was coined by the company that created the idea, you don't see "glasses in about a 1/2 hour" or other variations as often. BTW I think they are refered to as "Super Opticals". The same thing applies to the concept of FF if we can just pick a term and all use it their would be less confusion, but I suspect that it's not as profitable this way so we have:
Digital
FreeForm
Free-Form
HD
360
I probably missed a few but you get the drift they're all different brand names for the same process being utilized. So lets just keep on using the various terms and then every few months talk about why no one really understands it.
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Indeed! There are no metrics and if they were they could not be practically correlated with visual acuity. By analogy, its like trying to measure turds and correlating their size and shape with ones constipation or lack thereof.
In addition we are using terms and technology such as "freeform" and "digital" which had established meanings in NC manufacturing long before their adoption by ophthalmic lens manufacturers marketing departments.
So are you saying I forgot:
CNC
:D, the topic sucks because of all of the nomenclature that must be sorted through before we can even discuss anything of merit witnessed by the original post. It's nice to see when companies start to try and make sure there is a level of understanding but I can't help but to feel like it's too little too late. A moajority of opticians I know have a really bad understanding of FF and progresssives in general and they got it directly from their reps so they believe it as accurate and truthful information.
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*Dave at OptiVision has a web based tracer integration package that's awesome.
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