Today I decided to get myself a Tripod and go out and take some night shots. It went grat but on some photos I get an upside down reflection of the lights. For the shot attached I used a sigma DG 70-300mm lens zoomed in completely on a Canon XSI. I have a Tiffen UV Protector lens attached so might that be the cause of the problem? I'm new to photography so thanks ahead of any tips.