hello if your nikon camera is af mount, yes, you could make the sigma 70-200mm f/2.8 ex dg apo hsm large aperture macro zoom lens work with canon with this adoptor 

Dear Customer, it could fit your Sigma f2.8 24-70mm lens with 82mm threads. 

Look on the lens and it will tell you the size of the filter required,. 

The V50x comes with a skeleton case with a slotted rear door replacement, but there is no opening to allow plugging in an external mic. As a note, the sound recording, even while in the completely waterproof case, is better than I had expected. If you're not worried about moisture, there is a threaded tripod mount on the bottom of the camera and an adapter that will allow you mount the camera without using the case. 

HI your fujinon m42 55mm 1.8 and a sigma-z m42 135mm 2.8 are M42 mount, the item can fit your camera and lens