Cokin ND Filters – Not very Neutral – Colour Cast Problem

Recently I bought a starter set of graduated filters from Cokin in what they call they P series.

This consists of a holding mount to hold the filter plates, the filters themselves, and a adaptor ring – read more here

This weekend I went out to play with them and found that I was getting a horrible pink cast over my images when I was staking filters.

2x Cokin 4 stop ND Filter - 25 Sec

Below is a the same shot taken with just 1 ND 4 image and although the pink cast looks to have gone, at 100% you can still see a slight tint. This leave me to believe that with longer exposures the effective is cumulative.

1x Cokin 4 stop ND Filter - 8 Sec

At first I thought it was the white balance but even the raw images have come out like this.  Now its possible to effectively remove the cast in Photoshop, but it is not the point.  I wanted to spend less time in front the computer and getting more shots correct ‘in camera’.

After a quick search on Google I found this article on Flickr - http://www.flickr.com/photos/brentbat/2372603825/

It effectively tells me that the Cokin ND filters are, to be blunt, cheap and if the effect they give is not what you want (you bought a neutral density filter you expect it to be neutral) pretty useless.

Take a look at the sample picture below take from the post on Flickr and see what I mean.

ND Filter comparison - Cokin vs Singh Ray

Now I know the pink does sort or look nice in the example, but its not neutral and it certainly wasn’t what I wanted in the first example.

After reading the responses on Flickr and a few other sites it would appear that this is a know issue with the Cokin ND range and seems to stem from the fact that they let in to much Infra-Red light.

Based on this alone I am now looking to upgrade my filters to either Singh Ray or more likely to Lee Filters (http://www.leefilters.com/camera/) which are excellent.  If it wasn’t for the cost I would have bought them in the first place, but as with all things in photography – it seems you only get what you pay for.