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edmundo
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 12, 2004 - 11:47 am: | 
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Not strictly a repair question, but form I have seen in this forum, I think there's enough knowledge to answer this: the coating on lenses is used to control internal reflections only, or it contributes to the overall colour balance, correcting/adjusting it to a neutral point ? |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 12, 2004 - 12:06 pm: |
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The primary goal of coating actually was reducing internal reflections. A single layer coating will reduce reflections in a certain range of wavelengths of the light only, so the light transmission of single-coated lenses will not be even over the entire spectrum of light.
So manufacturers introduced techniques of giving different kind of coating to the single lens elements of a lens. Later multicoating was introduced which allows to control the color balance of a lens which might be disturbed not only due to the properties of a single-layer coating but also due to the properties of some optical glasses which also do not have even light transmission, i.e. in most cases they will give a yellowish tone. To compensate this, manufacturer use coatings which have slightly more reflection of the yellow part of the spectrum, thus compensating the absorbtion of blue light. |
Jon Goodman
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 12, 2004 - 12:13 pm: |
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Edmundo, I think you've asked two questions that are connected. Internal reflections/flare will wreck many aspects of picture-taking (including, but not limited to: contrast, color balance, sharpness of detail, etc). So, maybe the right answer is..."Coating on lenses is used to control internal reflections. Minimizing reflections/flare will improve contrast and overall color balance."
Jon |
edmundo
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 12, 2004 - 01:34 pm: |
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Thank you both, I used to think that coating was only for reflective control... the answers were very clear and informative.
edmundo |
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