Filter forms and X?

I bought my first ND filter today, it is a Tiffen 77mm Variable ND. When I turn the filter to its max darkness the filter brings two lines from the side to form an 'X' in the middle of my viewfinder, with a small amount of light showing outside the 'X'. It does this at all apertures. I tried it on a Canon 17-40mm L and my 5D Mk 3. Since I have never owned a variable ND filter before I don't know if this is normal, or if it will cause problems. Does anyone have any advice they can give me?

Chiefy wrote in post #15891679
I bought my first ND filter today, it is a Tiffen 77mm Variable ND. When I turn the filter to its max darkness the filter brings two lines from the side to form an 'X' in the middle of my viewfinder, with a small amount of light showing outside the 'X'. It does this at all apertures. I tried it on a Canon 17-40mm L and my 5D Mk 3. Since I have never owned a variable ND filter before I don't know if this is normal, or if it will cause problems. Does anyone have any advice they can give me?

I may have answered my own question. I read this last night before I purchased the filter but it did not register I guess:

The cross pattern is bad on the wider angle setting and will be noticeable on photos when you reach the seventh stop or more. You can see from the last three frames at 24mm, that the cross pattern is much less of a problem when you use longer focal length lenses - the last dark frame was, like all other frames, on auto and the camera meter has been fooled. You need to remember to increase the exposure when shooting at the maximum setting - even the middle exposure needs a small exposure increase to compensate.