How to check coatings on a lens??

[Bean]

Would like to know the following

1. What does the coating on the elements of the lens do to the image?
2. How will the image suffer if some of the coating of the elements are gone or eaten up?
3. How do you check a 2nd-hand lens that the coatings are still there?
4. How much coating on each elements are there on a typical lens?
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   :dunno:
   :dunno:
   

 

[Kho King]

Originally posted by Bean

Would like to know the following

1. What does the coating on the elements of the lens do to the image?
   
   > better light transmission, and less internal reflection.
   
2. How will the image suffer if some of the coating of the elements are gone or eaten up?
   
   > uneven light transmission, might not be able to notice though.
   
3. How do you check a 2nd-hand lens that the coatings are still there?
   
   > Look at the surface...about 130 degree to your eyes...and you should see good even colour on the glass surface.
   
4. How much coating on each elements are there on a typical lens?
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   > different company apply differently.