Hi I'm new to film photography and send all my film to a pro lab for processing. I've been testing different varieties of black and white film to find the ones I like best for serious work. I recieved a roll of t-max 100 back the other day and most of the skies show a problem. The attached file shows a crop of the sky of one of the worse images. The first is a standard scan and the second one has the levels adjusted to show the problem more clearly. I'm wondering if this is a processing problem or whether it could be caused by a filter? I'm using some rather cheap Lee colour filters made from polyester. They are square and quite bendy. I'm pretty sure I used an orange filter on this one. Thanks.