If you use any polarizer under daylight, the colors are changed, since skylight is partially polarized. I'd expect it to be warmer, since some blue gets suppressed in the shadows or on slightly glossy surfaces like the roof.

If you want a neutral test, compare under controlled artificial lighting.

@Swiss_Boy Hi thanks for the test, I have been looking at lot at this Marumi Filter for some time but had no feedback and test on it on the internet. From your test there seems to be quite a difference. The image with the filter seems to be warmer and ... strangely less contrasty. The highlight seems to be tamed. My only explanation is that it is the polarizing effect producing that. In fact it is not bad, some would say a more organic look. In terms of sharpness it seems a little less sharp even if you factor in the difference in contrast. I think a little sharpness in post could put them on par for those that like very sharp image.

If ever you have time it would be very nice to do some example as above at different ND level to see about any colour cast and usable range. The second thing is longer focal length like at least 100 mm, because most of the time this is where the image get softer. These two are the main problem in those Fader ND filters. I am getting fed-up by the internet scam of these pseudo review site that are just there to get referral money and advertising. This name brand filter could be the first good affordable Fader ND to the mass.

@feha

The difference is striking using these with the @LPowell flowmotion patch!!!

These are the listings for the filters from filmtools:

These are all out of stock:

Shane Hurlbut's kits:

http://www.filmtools.com/tiffen-77mm-indie-neutral-density-kit-w77indndkt.html

http://www.filmtools.com/tiffen-77mm-indie-plus-hv-kit-w77indndpkt.html

Tiffen special DSLR IR cut-off filters:

http://www.filmtools.com/tiffen-77mm-indie-pro-irnd-kit-w77indprokt.html

http://www.filmtools.com/tiffen-77mm-indie-standard-irnd-kit-w77indstdkt.html

This one is in stock:

http://www.filmtools.com/tiffen-77mm-indie-upgrade-irnd-kit-w77indugkt.html http://www.bhphotovideo.com/c/product/729157-REG/Tiffen_W77INDUGKT_77mm_Indie_Upgrade_Infrared_Neutral.html Adorama has some singles in stock, but it is cheaper to get a kit!

The main difference is Shane Hurlbut's kits have no IR blocking function at all.

@bubba , Please can you point me the Tiffen filters you are using, link ?

All Marumi filters are good quality, very respectable brand in Japan. I use their ND's exclusively stacked when needed, not tried their Vari-ND though, but would be surprised if it didn't perform as expected.

I have a 62mm Heliopan Vario ND with a step down adapter to 46mm (to fit the 25mm and 14mm primes). Purpose is for filming snowsports (mostly snowmobiling) where the snow can be "blindingly bright". I'm happy with it, but I only make home movies and have nothing to judge it against.

@bubba thanks, in fact I was going to ask the question if it was ok to stack them to be able to have more ND.

@bubba Not to nitpick, but stacking 3 traditional ND filters cuts 99.999% of IR, 57.8125% of near-IR, and 31.8528% of the red spectrum.

The math goes like this, taking near-IR as an example: 100%-[(100%-25%)^3], or 1 - .75^3.

Of course this is still only an approximation using somewhat-arbitrarily designated categories, but it is more accurate than adding percentages.

@danyyyel

Buy the Tiffen. Thats's the best! I've had no problems with that set, at all, ...even stacked high to get minimum light reduction.

@cp_from_oz

They do not interfere with AF system of mirrorless cameras using contrast AF, like all Panasonic cameras. With DSLR you can have linear polarizers affecting AF, yep.

I'm using a Genus ND and don't have any issues. Color and IQ are good.

All my filters are 77mm and do have issues with the step up adapters on faders. For some reason they all get stuck on the filter at some point and are impossible to remove without destroying the ring. (Yes, I have filter wrenches.)

@Swiss_Boy @bheath Okay, just a quick response to you guys from my phone before I grab the laptop and head for the nearest Wi-Fi.

@Swiss_Boy Larger filters can be used on a wider variety of threads, so functionality wise it makes sense to get the largest you can afford. Of course the larger they are, the more expensive they get. My largest lenses use a 77mm thread so I tend to buy filters that size and use step-up rings for the rest. If you use a step-up ring with a larger filter, you also decrease the chance of vignetteting. Ofr instance, when I use a 52 to 77mm step up ring, I can fit 4 77mm contrast filters onto the lens without signs of vignetting on the Gh2 in standard 24H video mode. If I put 2 of the same filters on another lens on a 1.6x crop body, I can already see vignetting. It is not a scientific experiment (too many uncotrolled variables, like the lenses) but it gives you an idea of the potential.

@Bheath It is a great filter. I shot the partial eclipse with it using a Canon 100-400mm L series. Gorgeous.

sorry I did not read this before:

Jow to order Heliopan Vari filter from a german site http://www.fotomayr.de

I don't know the german site, and I don't know how credible the ordering process is.

I know Fotomayr for many year since I was running my own E-6 film lab. Over all these years they were reliable and had a excellent service. I bought 2 Heliopan ND faders last year from there.