I shot about 900 photos while on holidays in Hawaii and did them all in RAW and mostly using a cheap Circular Polarising Filter. No problems with the colours but the photos all seem to be quite noisy with general noise plus oblong JPEG-type artifacts. Easily fixed using Topaz DeNoise but just wondering if this is typical of RAW images or if the filter was the culprit. I usually shoot JPEG but appreciate the flexibility of white balance adjustments in RAW. I used a Nikon D5100 and usually set ISO400 to allow a good balance between still and action shots.

Your advice would be greatly appreciated.