Both are equal.
The purpose of the ellipse is to show that there are only two curves for every power(see attached) that will produce a lens free from oblique astigmatism, which is simply not...
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Both are equal.
The purpose of the ellipse is to show that there are only two curves for every power(see attached) that will produce a lens free from oblique astigmatism, which is simply not...
In 1804 Dr. William Wollaston published a study that stated that curved meniscus lenses have slightly better imagery than bi-convex.
In 1898 Dr. Franz Ostwalt calculated each power within a range...
Your axis from the two eyes is only 5 degrees apart.
It may seem like the axis was reversed, however, the compensation was done for the near area.
Near area compensation is done the same way, but...
ZEISS has a full portfolio with 2 free form SV, 1 anti-fatigue and 4 progressives called SmartLife. The names will sound familiar as we kept the names, but it is not re-branded designs.
SmartLife...
I am happy to send the white paper to those that are interested, send a note to Brent.mccardle@zeiss.com
Standard SV includes spherical, aspherical, and double aspheric, which can be stock(FSV)...
These are very good points!
Using a blue blocking lens that reduces blue violet light will increase the contrast of the screen and may lead to a reduction of symptoms common to digital eye strain....
SmartLife Pure and SmartLife Plus are compensated for default PoW and cannot be changed.
SmartLife Superb and SmartLife Individual can be changed or altered from default PoW. If not PoW is given...
You can specify a wrap and pantoscopic tilt on SmartLife Superb or SmartLife Individual.
Max wrap is 15 degrees and Max pantoscopic tilt is 30 degrees.
There is an Individual Sport which offers a...
The SmartLife Single Vision compensates for default PoW only where the SmartLife Individual Single Vision allows you to choose the PoW if you can and want to, but you are not required to.
...
It was not just a renaming of product. The SmartLife portfolio includes two free form SV, a Digital Lens(low add powers ranging from 0.50 - 1.25) and four progressives, which have the same...
Follow this link
I used polycarbonate on an 8.00 BC to obtain the values.
When using the approximate thickness formula, you should put this through a while loop to get a more accurate value.
OS67 means that the lens is an Office Lens in 1.67 material. On the temporal side you should see something like ##100 or ##200 or ##400, where ## could be 20 or 40 or 30, this does not matter. The...
Since blank size is no longer a concern due to free form production the PRP location ultimately is not relevant. One could say increased distance between the fitting cross and the PRP reduces prism...
The formulas remain the same: TCA = P/v
The difference is in how you determine prism amount. Using Prentice's rule you do not take the the angle of incidence and refraction from both surfaces...
As the thickness increases the prism amount increases thereby increasing the transverse chromatic aberration viewed by the wearer.
The prism looking 30 degrees away from center in a +5.00 with a 4.2...
You would have to use a Superb or Individual to specify PoW. You could also use one of the Sport options if the base curve is steep enough.
You can approximate the transverse chromatic aberration(TCA) by calculating where you want to calculate the TCA.
For example you could calculate a +5.00, 15mm from center in a material of 1.6 with a...
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....
Ha! I can justify my pay this week 😀
1. The Precision portfolio is separate from the SmartLife portfolio. It is not re-branding, but the progressive names of each portfolio are the same. We...
My apologies for being unclear.
The SmartLife Portfolio includes four progressives, one anti-fatigue lens and two free form single vision lenses.
The four progressives in the SmartLife portfolio...
This link is to our Precision Portfolio, where the Pure had fitting heights of 13, 15, 17, 19 and 21
SmartLife Pure has three fitting height(S = 14, M = 16, L = 18)
The Precision...
Not sure about this comment, but thank you!
Are you referring to the original Individual? If so there have been many improvements over the years and the Superb and Pure would be much...
The Light D has two fitting height options, 18 mm and 14 mm (Light D 18 and Light D 14), these are the minimum fitting height. The corridor length for the 14 is ~10 mm and the 18 is ~14 mm. The...
In order for a lens to be free from astigmatic blur at all gaze angles light should come to a point focus on the far point sphere(center of rotation - focal length of the lens). This imaginary sphere...
I had created a sample page to show the differences in weight, thickness and chromatic aberrations a while back.
I titled it The War between Optics and Cosmetics, after Barry wrote his article in...