# Search:

Type: Posts; User: lensgrinder; Keyword(s):

Page 1 of 20 1

1. ## Thread: Lens thickness & fitted back vertex distance

by lensgrinder
Replies
34
Views
2,991

### Assuming a demo lens with 6.00 D back curve the...

Assuming a demo lens with 6.00 D back curve the sag of the back surface will equal 3.63. Let's assume we place a +5.00 D lens in the same frame with a 7.50 D front surface, the back surface sag will...
2. ## Thread: Lens Thickness - Base Curve Consideration

by lensgrinder
Replies
4
Views
735

### This formula is the sagittal approximation...

This formula is the sagittal approximation formula which uses the power to approximate the thickness. You will also need to add the minimum thickness to get a better approximation.

To get a more...
3. ## Thread: Finding True Curve

by lensgrinder
Replies
2
Views
1,338

### D = (n-1)/r 2.5 = (n-1)/0.20387 0.509675 = n -...

D = (n-1)/r
2.5 = (n-1)/0.20387
0.509675 = n - 1
n = 1 + 0.509675
n = 1.509675

F1 = (2.5 X 0.509675)/0.53
F1 = 2.4041273585
4. ## Thread: Widest intermediate with a Zeiss lens

by lensgrinder
Replies
3
Views
2,087

### Even though the frame fit value is 4 mm the...

Even though the frame fit value is 4 mm the corridor will be slightly longer in the Indivdual 2I and slightly shorter in the Individual 2N. When you have a longer corridor the rate of change is less...
5. ## Thread: Widest intermediate with a Zeiss lens

by lensgrinder
Replies
3
Views
2,087

### A wider intermediate comes at the expense of...

A wider intermediate comes at the expense of either reduced distance(clarity from side to side) and slower rate of change(the amount the power changes through the corridor over a given distance). ...

by lensgrinder
Replies
1
Views
718

### The synchrony Easy View HD replaced the...

The synchrony Easy View HD replaced the Instinctive and it comes in CR-39 polarized.
7. ## Thread: Help Identifying Zeiss marks...

by lensgrinder
Replies
2
Views
933

### PU is Zeiss Precision Pure and 59 is Polycarbonate

PU is Zeiss Precision Pure and 59 is Polycarbonate

by lensgrinder
Replies
44
Views
5,307

### If your lab is compensating the power for vertex...

If your lab is compensating the power for vertex distance then they would perform that calculation prior to tilt and wrap calculations. If you perform the calculation order for the vertex...
9. ## Thread: how to calculate power away from the OC.

by lensgrinder
Replies
17
Views
2,298

### I really enjoy sitting with pencil and paper and...

I really enjoy sitting with pencil and paper and sketching a good ray trace. Instead of aspirin, maybe use beer, whiskey, wine, etc. :smile:

by lensgrinder
Replies
44
Views
5,307

### I should have been a little clearer, it is not...

I should have been a little clearer, it is not being compensated for power changes in regards to fitted vertex versus refracted vertex, because no one gives the refracted vertex when the lens is...
11. ## Thread: how to calculate power away from the OC.

by lensgrinder
Replies
17
Views
2,298

### You will need to perform a backward ray trace...

You will need to perform a backward ray trace from the eye's center of rotation(stop distance). You will need to know the material, thickness, R1, and R2, vertex distance, center of rotation, and...

by lensgrinder
Replies
44
Views
5,307

### Vertex distance is not being used in the...

Vertex distance is not being used in the compensating calcualtions, just tilt and wrap. If your manufacturer takes center of rotation into account then the vertex distance is used in addition to the...
13. ## Thread: Need Zeiss PAL Information

by lensgrinder
Replies
9
Views
2,723

### Although it is marketed as a back up lens for CL...

Although it is marketed as a back up lens for CL wearers it is a good overall lens design especially for the hyperope, as hyperopes tend to like smaller fields of view due to the magnification and...
14. ## Thread: Need Zeiss PAL Information

by lensgrinder
Replies
9
Views
2,723

### EnergizeMe PAL with 3 fixed fitting heights

EnergizeMe PAL with 3 fixed fitting heights
15. ## Thread: Drivesafe SV vs Drivesafe Individual SV

by lensgrinder
Replies
3
Views
1,401

### DriveSafe SV is compensated for default PoW...

DriveSafe SV is compensated for default PoW values
9.0 degrees of pantoscopic tilt
6.5 degrees of wrap
12.0 mm BVD

DriveSafe Individual SV allows you to customize the PoW values. If you choose...
16. ## Thread: Periphreal Distortion in Pt. Switching from Trivex to Poly

by lensgrinder
Replies
15
Views
2,469

Let us assume the Trivex and Polycarbonate were on the same base curve, they were not rotationally symmetrical aspheric lenses or free form lenses, and all other PoW...
17. ## Thread: Can we please take a moment to hate on Zeiss?

by lensgrinder
Replies
9
Views
2,042

### You have concerns and I am willing to try and...

You have concerns and I am willing to try and resolve them if you want my help.
18. ## Thread: Can we please take a moment to hate on Zeiss?

by lensgrinder
Replies
9
Views
2,042

### I work for Zeiss and would be happy to address...

I work for Zeiss and would be happy to address your concerns.
Please email me brent.mccardle@zeiss.com so I can look into your account and address this on an account level.

To say they do...
19. ## Thread: Any suggestions for a substitute for a Zeiss Gradal Brevity progressive

by lensgrinder
Replies
2
Views
2,158

### ¥ou can use a GT-2 short or a Zeiss Choice 13.

¥ou can use a GT-2 short or a Zeiss Choice 13.
20. ## Thread: Does anyone work for Zeiss?

by lensgrinder
Replies
4
Views
943

### You can call me. I will PM you as well. My...

You can call me. I will PM you as well.
21. ## Thread: pantoscopic tilt and face wrap

by lensgrinder
Replies
30
Views
4,968

### I love to geek out, but it seems I am late to...

I love to geek out, but it seems I am late to responding to this thread.
DRK, the effective power is the effect of changing parameters. For example, when you prescribe an Rx of -10.00 at a...
22. ## Thread: pantoscopic tilt and face wrap

by lensgrinder
Replies
30
Views
4,968

### http://calculators.brent-mccardle.org/pow.html ...

http://calculators.brent-mccardle.org/pow.html

Use this link to get the effective calculation. This calculation gives you the effective power if not compensated. Keep in mind the calculations...
23. ## Thread: Need Zeiss PAL Information

by lensgrinder
Replies
9
Views
2,723

### I work for Zeiss and would be happy to talk with...

I work for Zeiss and would be happy to talk with you about our products.

We have five general purpose progressives, some with fixed corridor and some...
24. ## Thread: Aspherics and power variation in periphery.

by lensgrinder
Replies
44
Views
7,831

### A molded aspheric lens is rotationally...

A molded aspheric lens is rotationally symmetrical, meaning that if you measure from the center outward to a point and measure again from the center to the same distance but opposite the other point...
25. ## Thread: Fixed vs variable corridors.

by lensgrinder
Replies
17
Views
7,087

### No worries, I created that name years ago. The...

No worries, I created that name years ago.

The viewing fields that are referred to are controlled in most back surface free form lenses. A variable corridor lens can control this more than a...
Results 1 to 25 of 480
Page 1 of 20 1