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Looking at previous shots I've taken, I see that when I'm indoors and shooting outdoors with glass in between, I sometimes get glare. I know that realistically if I can get outside, the shot looks a lot better but sometimes that isn't an option, or it is inaccessible.
The only way I've found to reduce glare is to remove the lens hood and put the lens right up to the glass but I'm unable to get different perspectives except ones tangential to the glass.
Are there ways to mitigate or reduce glare, before post production? Related when is glare most predominant/likely to occur?