Hi all: I have a Canon T5i and a Tamron B008 18-270 zoom lens. I'm going plane spotting in a few days but the observation deck is behind a glass wall. I bought a polarized filter but am having trouble figuring out how to use it. My concern is glare from the glass. While I'll be spotting during daylight, I wanted to practice tonight, but since its dark out, I'm trying in my dining room. We have a China Cabinet with polished wood and glass windows. I took four shots, rotating the filter 90° between each shot, but I can't tell the difference. I admit I may not be using the right environment for learning, but it was worth a shot. I do have a few specific questions though: 1. How do I know from looking at the filter if it is on or off? There are no markings on the perimeter other than the manufacturers name and model number. 2. If my filter is fully off, meaning minimal effect, how many degrees do I rotate it to get full effect? I'm assuming it's either 90º or 180º. 3. What is the best way to test the filter? I was going to go out and sit in the car tomorrow behind the windshield and take some pictures looking out. Photo Forum - Polarized Filter - Google Drive Here are the pictures that I took tonight, for what it's worth. I uploaded them to my G-drive because they are too big to upload directly. Can someone please help me with this? Thanks!!