Hi, Got a free screw on filter with my HS2. Not quite sure what it does. From what I can ascertain, the filter will improve contrast and black level at the expense of light output in a 'lit room' As my room is dark is it something I need to use? To me, it seems to add a purple hint to proceedings. I would like a clear explination as to what this type of filter is for, if there are any other Sony users out there, HS2, HS10 or otherwise. Thanks, Captain Benefit.