In the film era a vast amount of filters was needed to alter the colours, the temperature or to add certain effects to the photos. In digital photography many of these filters have become pretty much useless as they can be recreated in post processing with the added bonus of more control over the effect without any disadvantages.
But there are also some useful filters which can’t be fully recreated in post processing and still have a place in digital photography and these are the ones I’m going to talk about.
Update 09/27/2016: at Photokina 2016 in Cologne I checked out all the big filter manufacturers and have updated some sections accordingly. I am also working closely with NiSi filters now – not just because I think their filters offer the best quality – but because they listen to their customers and I hope to be able to help them develope the first holder I find nothing to complain about 🙂