Discolor using CPL


#1
Hi guys... when I uses CPL to take photos through the windows or to take photo of cars, I noticed some discolor on the glass portion...



Note the windscreen section got some greenish light... Is my CPL problem or am I suppose not to use CPL when taking photo with cars etc?
 

Octarine

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#2
Windscreen glass is not really clear glass, there are anti-reflection coatings and other add-ons. The tint is the result of the light reflected by the windscreen and the CPL filtering.
 

#9
Haha!

I know it can turn LCD screen totally black as I have tried it before... haha! Guess I cannot use CPL when taking shots of cars or through bus windows etc... Guess it only affect those black tinted wan bah... If not wrong those clear clear wan should be ok....
 

Octarine

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#10
If not wrong those clear clear wan should be ok....
The "clear ones" (I hope my guess is right) only appear clear, but they are not. Have you used any polarizing sunglasses and looked at cars in the sun? If not, do it and you will notice some patterns that look like oil stains on water, but with a regular pattern. These patterns are caused by the manufacturing process. They will become visible the moment you use your CPL.
 

#11
The "clear ones" (I hope my guess is right) only appear clear, but they are not. Have you used any polarizing sunglasses and looked at cars in the sun? If not, do it and you will notice some patterns that look like oil stains on water, but with a regular pattern. These patterns are caused by the manufacturing process. They will become visible the moment you use your CPL.
Noted... Haven't really tried using CPL to check out those clear glasses... So far I experience this issue through car windows... Guess they are all design to be like that... maybe some UV protection or something like that...
 

daredevil123

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#12
Noted... Haven't really tried using CPL to check out those clear glasses... So far I experience this issue through car windows... Guess they are all design to be like that... maybe some UV protection or something like that...
Car glass is not plain glass. It is glass sealed in resin with god-knows what else is included in the processing. That is why it is shatter proof.. Also, most cars now have tinting film on top as well. So all theses add up, you are bound to see weird patter on auto glass.
 

Alpc

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#13
Actually, I think it depends on how you do it... I have occasionally found all my photos having a blue tint to it, I have occasions where it turns out very well - my Highland day tour was one example as I shot out of the bus (glass) in some of my shots and it turns out great!
 

Octarine

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#15
hmmm.. out of curiosity, does this happen if those are not glass but plastic instead?
That depends again on the composition of the material. Similar to glass you can have all kinds of coatings, films and whatnot mixed in, giving you similar effects.
 

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