Review on SIOTI Square Filter Kit 100X150mm (4X6'') with ND2, ND4, ND8, and ND16 for Cokin Z, Lee, Hitech, Sioti Holder (ND) by Aries Greene

The optical quality is completely useless. I just took a bunch of test shots and couldn't get a sharp image at all with these filters. I'm using a Canon 6D Mark II body with a 70-200mm F2.8L IS Mark I lens. I've attached comparison images with and without the filter when the camera's aperture priority is wide open at 2.8 and the ISO set to 400. They are handheld but with a SIOTI filtered image and a shutter speed of 1/250s holding it shouldn't be a problem. blur. These images are SOOC RAW images. I stand 10-15 feet from the subject with great contrast. I can't use these filters at all. Also note that they use a SIOTI 100mm Square Z series aluminum modular filter holder which seems to be of decent quality. My problem is related to the optical quality of the filters themselves.