How to Reduce Or Eliminate Glare
Its funny, I've known about polarized lenses for a long time. I think I was a teenager when I was handed a pair of polarizing sun glasses to see into the ocean and remove the glare. When taking photos of my brother's artwork, it never occurred to me to use a polarizing filter.
Long story short, if you want to reduce glare in your photos, use a circular polarizing filter. It won't work on glare caused by light in the direction of the camera; it needs to be glare caused by light coming from a 90-degree angle. Take a look at these painting photos - it makes a huge difference. It adds contrast and not shown here but it really makes the colors pop.
No Glare, shot with a Tiffen circular polarizing filter on my lens.