Help: Inverted Vignette IRND 1.5 Tiffen Filter

[JRJenkins]

Hi,

 

I've had a Tiffen IRND 1.5 filter recently returned and the filter appears to have a darker center then the outside, almost as if where the 4x5.6 filter tray sits is one tone and the exposed filter inside of the tray is a darker shade.

 

Has anybody seen or heard about this before?

 

When placed in front of a camera, it's unseen, however very obvious to the human eye.

 

Thanks.

[Dan Muchnik]

It's a center nd used to compensate for the harsh vignetting common on older super wide lenses shot wide open. As far as I can guess anyways...