Here's a test I did today with the Vivitar NDX variable filter. I have been in post on my latest doc, "Three Days at Foster," and I've been working overtime on color correction. I used this particular filter on my Zuiko 45mm because the filter was for 37mm thread. I knew there were concerns about color cast and loss of sharpness, but a lot of what I shot was lovely anyway. The rest, I'm fixing.
So, for this test, which is probably not well done, I set up my GH1 with the reliability hack and set it to smooth with everything -2. I manually white balanced on the white door with each test after I set exposure. I pulled focus using a loupe.
To my eye, the one with the filter on it and the extra LED light does look, perhaps, a little less sharp. When I sharpened, it became a little more clear that there may be a slight loss of sharpness. But you guys look at it and tell me if my eyes need to be reset.
I ran three cameras on my doc (two GH1s and an HMC150) and was able to find an angle every time that worked. But I did not properly pay attention to color on some shots and tried to dial it in. After this test, I'm going to manually do it moving forward. Actually, I did manually balance with my video camera (the HMC150) on each interview, which did make a difference.
My main question is: now that Light Craft has a 37mm variable ND available at Adorama, based on this test, how much better would it be?
Finally, I realize that the casting and focus issues would become more pronounced as I cranked the ND down (darker), however, mine was set in the middle of the scale on the side of the filter, which I thought would be good for this test.
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