I think the darker one is a neutral density filter. I believe the I1 camera has an aperture locked at f2.8. So, to get a correct exposure, the camera will vary the ISO and shutter speed. In some cases (maybe rare) the camera won't be able to get a shutter speed high enough and an lSO low enough to avoid blowing out some highlights in your picture. You should try both on a bright sunny day and see which you prefer. I will probably use the clear glass filter 90% of the time, but on some bright days, the ND filter may help balance the exposure some. I would recommend you ALWAYS have at least one filter on the front just to protect the front element of the lens. I have broken a few filters on my DSLR lenses and gladly paid the money to replace the filter knowing that it was much cheaper than replacing the front element of the lens . . . Being modular, I am sure you would need to buy a whole new camera if you even scratched the front element on the I1 camera.