Graduated Filter Colour Accuracy Testing

Tim Parkin

Amateur Photographer who plays with big cameras and film when in between digital photographs.

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Sometimes you think you've got things so right and yet, when you look at the result, you realise that something has gone significantly wrong. In the last issue I published the results of a series of test on graduated filters, even though I had a few doubts about the results. I didn't think the results were necessarily wrong, but they weren't showing something useful in the context of our landscape photography. If you're interested in the why's and how's of the testing, just have a read past the results and conclusions.

Results

OK, I've spent enough time analysing these graduated filters for colour that I'm happy to come to some general conclusions. I've worked out a colour difference between the clear part and the ND part of each filter (averaged across the ND zone of the filter) and this is given in terms of "Delta E 2000", a term used in printing to denote the difference between two colours in 'human' terms. Values of over 1 are 'visible' if placed next to each other. Most high-end printing companies consider any values less than or equal to 3 to be an acceptable colour match.