Help: Something obscuring part of the sensor?

[Lustgarten]

Af100, has problem now that looks like something obscuring the left side of the frame with any lense.

 

[Babu]

looks like you nd-filter wheel. make sure it's completely on 1 or any other number.

 

[Mike Harvey]

Yeah, freaked out a bit the first time this happened to me, but it was just the ND wheel not all the way in place.