From my tests I measured that the filter also reduces a little more than a half a stop of light transmission (0.60 – 0.75 stop), something that also was confirmed when auto editing the first images, so be sure to manually focus before attaching it in the lens (live view and/or focus peaking) because the decrease in the exposure will make it harder to focus when the filter is on, and also remember that you should alter your final exposure a bit, either in shooting or in post.
Personally I prefer to capture the photo as best as possible and only do minor editing in the final image.
So I suggest that you should alter your exposure, if possible of course, when shooting.
Keep in mind that almost all of today’s cameras are capable of producing great quality raw files that helps equalize the exposure flawlessly, so 1/2 stop of light is totally insignificant, however if for various reasons you can’t increase your exposure or you simply prefer the in-post method, you will still get a great result.
One other thing to keep in mind is that the filter works better under dark skies, although it can be used in light polluted areas.
Just don’t expect to capture the Milky Way Galaxy or the Orion Nebula from the center of a city just by attaching the filter on your lens.