Ewa-Marine C-A67 67mm Adapter Ring Set

This adapter ring does not come with the Ewa Marine housing, and having to purchase it separately, was annoying but the real problem became apparent once I tested it on the camera. Because it is at least 2x as deep as the other adapter rings, it creates significant vignetting at 18mm (with an APS-C DSLR), that only disappeared at 35mm, and I am a wide angle shooter, especially in the water. I am aware there are shortcomings with all soft housing type bags, and the housing itself appears to be more durable than others I've tried, but this is a defect that could be easily remedied. I tried a 58mm lens, with its adapter, and it did not vignette. Additionally, the lens port on the housing was not centered properly on the vinyl when manufactured, and as such, the vignetting is more extreme on the top when used in a horizontal format with the CA-67 Adapter. I have attempted with multiple emails to get a response from customer service at EWA Marine, without any response, which leads me to believe they are well aware of this problem, which could be resolved by halving the depth of the adapter. I am very dissapointed in the lack of customer support, and I would not recommend this adapter.