cameraland.nl I got the opportunity to test the Rodenstock Vario ND filter, a variable neutral density filter. Last year I got my hands on the LCW Fader ND mkII for a test (click here to see the results). Personally I was not very impressed by the LCW Fader ND, not even by the mkII. My main concern was the ‘cross’ (crucifix or ‘X’) the would show while using a wide angle lens. It appeared on my Canon EF 24-70mm f/2.8 USM so I didn’t even bother to test the Canon 16-35mm f/2.8 USM II. (See on the example of the cross issue on this page.) So I was hoping the Rodenstock Vario ND will perform better.
With the filter from Rodenstock I decided to give it al full test. I tried it on almost every piece of glass that I own. This caused a few problems due to the fact that I got the 82mm version of the Rodenstock Vario ND for my test and most of my lenses have the 77mm thread. So I needed an adapter ring. Normally this wouldn’t be a problem but this time I experienced vignetting on my Canon 24-70mm f/2.8 USM when set to 24mm. And I do not know if the vignetting is caused by the filter itself or by the use of the adapter ring. The 82mm showed some vignetting on my Canon 16-35mm f/2.8 USM II when set to 16mm at f/2.8. I didn’t really experience vignetting when set at f/22.
As you can see on the example below, I took 9 shots (‘no filter’, min, +1,5, +2, +3, +4, +5, max, beyond max) for each lens/aperture/zoom-level combination. (ie. for my 24-70mm I shot on 24mm and 70mm, at f/2.8 and f/22 – so that adds up to 4 x 9 shots for this lens)
impressed by the Rodenstock Vario ND, and especially not due to the high(er) price range of the Rodenstock Vario ND MC. I still experience the cruciform issue (the big black ‘X’) and that occurred in most cases right after the ‘max setting. While with the LCW Fader ND mkII in some cases I able to use a higher setting before I encountered the ‘X’. The filter is officially sold as a variable ND with a range from 1-9 stops, (i.e. 2,8x-400x) In none of the occurrences during my test I was able to use the filter beyond the max setting which is in most cases is equal to +6 stops. So you will not be able to use +7 till +9 stops. If anyone has other (better) results I am more then happy to hear from you. So that makes me wonder why they even bother to sell it as a 1-9 stops range filter. Has to be a commercial decision I guess.
The main difference that I experienced was the lack of color shifts in the +1 till +5 stops range. In some occasions I experience loss in light at the +5 stop setting (ie. darker then expected results) so I think that my light meter got fooled by the use of two polarisation filters. I also experience loss of contrast, but that is of lesser concern to me due tot the fact that this is something which is easy to correct when using RAW.
Overall I think the Rodenstock Vario ND is a better option compared to the LCW. This due to the fact that in the +1 till +5 stops range you get better, clearer, and sharper results.
So if you need a variable ND filter the Rodenstock Vario ND MC is a very good option. But if you need more than +5 stops for neutral density or grey filtering – buy a fixed filter and avoid the variable ND’s all together.
Click on the images below to see the test results for each lens combination.