EOS 6D Mark II strange dark areas using ND filter

[Skip70]

6D Mark II

I am getting the dark areas when using my variable ND filter. Generally, I can go 3-4 stops with no problem, but anything after that, these dark areas appear. It happens whether I am using Av or Manual exposure. K&F Concepts, filter, so don't imagine it's the filter itself, but don't know. dark areas using ND filter

[Skip70]

For some reason, I am not able to edit my post. I wanted to add that these uneven dark areas do not appear through the viewfinder or Live view. Only in the final image. 

[Peter]

Variable ND filter x pattern.

[AtticusLake]

I'd say this is very unlikely to be the camera, and is almost certainly the filter.  Variable NDs generally do this kind of thing, if you push them to extreme ND levels, and in particular if you're using a wide-angle lens.  The EXIF data says you used a 28mm lens, so that could be it.

You can solve this by using a longer lens, or by not pushing the ND level so far, or by using a fixed ND filter.

[rs-eos]

Agree with the others. I avoid using variable ND filters due to this issue. Though will say that this is quite an extreme case. Usually the X pattern is not this dark.

If you must use variable ND filters, suggest you look at better brands. The X pattern can still show up, but should not be anything as bad as what you’re experiencing.

[ebiggs1]

"If you must use variable ND filters, suggest you look at better brands. "

[Skip70]

Thanks for all the replies. Disappointing, but it is what it is. Maybe I'll get a fixed ND filter -- like an eight-stop to knock the light down a fair amount  -- and then just use the variable on top of that to fine-tune. 

[rs-eos]

Just use a fixed ND filter.  Don't "layer" a variable ND atop it.  If you need to vary the exposure, just adjust your shutter speed.  I would recommend with a 6-stop ND filter as many cameras can still focus with that when outside.  For closer to 10-stop, you'll need to acquire focus without the filter, then attach it afterwards.

[rs-eos]

Also, avoid cheap brands.  You don't want to end up with color shifts.  When testing B+W ND filters (my preferred brand), their 3-stop was perfectly neutral.  The 6-stop and 10-stop versions had a very minor shift in color (approx 50º Kelvin).

[AtticusLake]

Stacking NDs is probably not a good idea -- as Ricky says, you can get wierd colour shifts.  If you really need a variable ND, you can get them in high ranges, like 6-9 stops.  But I would really consider just getting a set of fixed NDs.  If you have an ND for every 2 stops, then you will always be able to get within 1 stop of the "correct" exposure; then you can fine-tine the remaining ⅓ or ⅔ of a stop using aperture and/or ISO.