TEST: CPL + reversed CPL as ND

As many of you know me, I love to do some tests and I always wanted to have a ND filter :) Long ago I made my experiments with 12 DIN wielding mask glasses used as filters but they weren't neutral density. These days I made a try with 2 CPLs (Circular Polar Filters) and had quite good results. Here are my experiences and a result :)

I ordered 2 cheap CPLs with 82mm diameter from Ebay and a step down ring to be able to put it on my CZJ Flektogon 50mm f4. Why this lens? Because I can make Tilt photography with it... so why not mix the two later? :D One of the CPLs got it's glass reversed and that's the one I had to put in front of the 'normal' CPL. These total around a bit more than a tenner... so not that expensive :) I will add a step up ring from 55mm so I can use my Tamron f2.4/24mm and could make long expo IR shots as well :)
So the test setup is: Pentax K10D + PSix->PK Tilt Adapter + CZJ Flektogon 50 + Cheap CPL + Cheap reversed CPL

• The pictures became a little 'contrastless' so shooting in RAW and after editing is necessary.
• Close to 90 degrees difference (where basically the 2 CPLs are 'killing each other') the whole picture turns to be blue...
• The white balance is going off to the cool side (pictures become 'blueish'). Again with after edit it can be corrected.
• The trees becoming 'rusty', it's the same effect I've noticed with Full spectrum photography done with the Panasonic FZ50 (this means both visible and IR light recorded), this makes me believe that IR is getting trough somehow... will make tests with the IR sensitive PanaFZ50 later.
• If I change the order of the filters (reversed on lens and normal CPL on 'light's side') then it doesn't has the darkening effect but still makes this blueish coloring... O.o
  

And here's the test shot (no filter vs filter turned to useable maximum):