The only filters I’ve ever used are UV or clear ones to protect my front elements on digital cameras (I know, I know). I was looking at ND filters one day to allow shooting with larger apertures in sunlight and stumbled across an article about circular polarisers. I liked how they remove reflections and add depth to cloudy skies, so I ordered a couple of cheapish Tiffens from Amazon that claim to block a stop and a half of light.
At last the package arrived, so I grabbed my Pentax 6×7, the 90mm 2.8 and a roll of Ilford Delta 400.
I took a walk to Punggol Park which is not far from where I live in Singapore. I tried to pick scenes with lots of light, contrast and reflective surfaces. It was very satisfying watching the clouds pop through my viewfinder as I turned the filter, and thinking about my angle in relation to the sun was fun too.
I developed the roll in HC-110 dilution B (1:31) for 7.5 minutes as per the Massive Dev Chart, and scanned it with an Epson V700.
I’m quite pleased with the results. I was able to pull bags of detail out of the highlights using the HDR sliders in Capture One – besides a little touching up and dust removal that’s all I did. I have not added any contrast or adjusted the curves.
As a side note, I did a bit of reading about the difference between circular and linear polarising filters. The difference is that circular ones have an extra layer that stops reflective elements in the camera system from causing cross polarisation. This is an issue with digital cameras, messing up autofocus and causing metering issues with DSLRs (because of the mirror). I guess the same issue might be possible in film SLRs with TTL metering that relies on the mirror – if anyone knows about this please let us know in the comments. Apparently for 35mm movie cameras there is an accessory called a video tap that uses a beam splitter to display a live video feed of what the lens sees – this too can cause cross polarisation with a linear filter resulting in a dark or black image.
So if in doubt, buy circular.