Image jump.

1. Fill in the blanks:

segment style	average pole position	image jump for +1.00 add	image jump for +3.00 add
Executive or Franklin	mm
PAL	mm
ST40	mm
ST22-25-28	mm
round 22	mm
Ultex A	mm

I'm not going to include those answers in the weekly transmission. Check here for the correct answers.
 

 

2. Why does the image jump not take the distance Rx into account?


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3. Why might it be difficult for a person who has been wearing executive bifocals for 35 years to adjust to a round 22 or to a FT28? Why might it be easier for this wearer to switch to a FT40? (aside from the increased width of the segment.)


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4. If a flat-top bifocal is 35 mm wide (side to side) and 21 mm deep (top to bottom), what is the actual pole position? 

 

5. A bifocal segment measures 28 mm from side to side, and 18 mm from top to bottom. What is the actual position of the segment OC from the top of the segment?  

 
 
6. List three possible uses for Fresnel optics on glasses.
   

 
7. List three disadvantages of Fresnel optics on glasses.
   

 
8. Describe (briefly) the application of Fresnel optic to a lens.