The lens used was a 300 mm f4 Nikkor and the camera was set in aperture priority mode (f 5.6). The camera set the exposure that varied over an 8 fold range.

I used the full range of Fotga settings and the results were all very similar, i.e. no better or no worse anywhere over the full range.

Apart from the results l Iike everything else about the Fotga. I would be interested in seeing the results from more upmarket filters.


Though I my tests were with a DIY vari-nd, it shows the same results as your's with a long lens, mine was a nikkor 80-200 f2.8.
HOWEVER, I found out that mated with the "right" lens, the filter can be consistently sharp at all apertures. In my case a 50mm f1.4 is sharp with the a vari-nd at all apertures and at different filter power settings.

For those interested here are the tests with color and resolution charts. And for those interested, how to DIY it.

DIY Vari-ND Experiment on Vimeo

Hi Ted,

I wonder why the longer focal lengths are so adversely affected? Does this happen with the up market versions?

Hi Alastair,

I recalled back I saw a shootout done with some brands, if my memory serves me right, they compared the Singh ray and LCW and it showed loss of sharpness with long lenses. I just can't recall which. The heliopan apparently is sharp and useful with several lens types. I have no personal experience with that so maybe someone who tried it can chime in.

On a side note, I use the mosaic VAF-5D2, and it does the opposite! The longer focal lengths are ok but on the wide end its picky with certain models.