I also ordered one of the variable Fotga filters. I did not order from their site, because shipping cost more than the filter. I ordered through ebay, and got free shipping. Anyway, I tested out something close to the Super Color 590nm and got this:
As I suspected, this variable filter is good for seeing what the effect will produce, but not so good optically. The center of this image if okay, but the edges fall apart. Anyway, this filter gives me a good idea of what to expect across the full range. With that information, I will then buy the optical quality filters I really like.
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