Heliopan Variable ND filter Question and Test

I recently purchased my first variable ND filter. I decided to take a few test shots to see if the filter compromised the image quality and discovered a much more disturbing problem. When the filter is rotated to the darkest setting (marked as #12) two dark arcs take shape around the center of the photo (see last photo). Is this common? Anything I can do to prevent it?

Also, thoughts about image quality with the filter on? I see a little vignetting and a slight greenish color cast, but overall sharpness seems to be very good. All shots were taken with a 60d and canon 17-55 f2.8 at 17mm and f2.8.

Control shot without filter.

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Kylemorgan88 wrote in post #13351296
When the filter is rotated to the darkest setting (marked as #12) two dark arcs take shape around the center of the photo (see last photo). Is this common? Anything I can do to prevent it?

With ND filter at marker #12

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Yes, this problem is common with variable ND filters when shooting at or beyond max density while at a fairly wide focal length. I use the Singh-Ray Vari-N-Duo with a full frame 5D2 and get the same result at focal lengths less than 28mm (you can do the math for a crop sensor) when I have the filter dialed to max density (or a little beyond max). The only option is to either reduce the amount of density dialed in, or zoom in to a bit longer focal length.

How is the IQ at 200mm?