So i have been trying my hand at IR photography lately, and i've heard of this problem as well as experienced it. When taking photos, i usually use a fairly long exposure. i usually end up getting a slightly over-exposed area in the center of the frame. A lot of people attribute this to the lens you use. I dont know if i believe that or not, i was wondering though, could this be from light getting in the back of the camera through the viewfinder that i forgot to cover?