I'm going to upset some of you because we all find a way to emotionally justify our illogical reasoning. And I'm no exception. But I don't use filters. I've never owned a UV filter & I don't use a polariser. I don't even use one of those inexplicably expensive ND (Neutral Density) or GND (Graduated Neutral Density) filters. I did once but not any more.
Some years ago during a moment of retail therapy weakness, I was persuaded by some marketing guru & bought a set of rectangular GND filters which in this instance were made by a Lee GND filter setThis is what spending nearly £400 on some plastic stuff made by Lee looks like. A 600mm wide, standalone dishwasher manufactured by Bosch in Germany costs less than this. company called LEE Filters.
They could have been made by that other French company whose trademark is annoyingly suggestive instead, of a class B drug but they are all basically the same.
They were made from an optical grade monomer called CR-39®. The proper name for this monomer is Allyl Diglycol Carbonate & it was patented decades, yes decades ago, by a company called PPG Industries out of Pittsburgh, PA in the good ol' US of A.
Retailers in "Rip-Off" Britain sell this brand of filters for around £75 each. The industry consensus seems to suggest that you "need" at least three of them. But having tried them, I suggest you don't "need" any.
Right now, I can hear some of you screaming that you would never have been able to get that "killer" shot without them. Perhaps but we might all agree that they are awkward to use without the £60 filter holder & the £40 lens adaptor ring. So a GND kit will set one back somewhere around £375. Sure, one can buy the whole set at a discount on Amazon but one will still spend the best part of £400 for a bag of plastic strips, a clip & a threaded, thin metal ring. How is this possible?
History of Plastic
CR-39® has been around since the 1940's when it was first used in military aircraft applications when it was called Columbia Resin #39 after the title of the research project under which it was invented. It was originally laminated with glass fibre to form fuel tanks for the Boeing B-17 bomber. And it is still widely used today to make for example, lenses for eye glasses because it is transparent in the visible spectrum & weighs about half that of optical glass. It also enjoys very low dispersion, similar to crown glass which is itself a high grade optical silica.
Singh-Ray soft edge GND filter & pouch3G means that the dark region will reduce the light transmitted by 3 stops. Measuring 120mm x 84mm, it fits the Cokin P series holder. But honestly, who cares? Plastic & Photography
Its introduction to photography is hardly novel either. The resin's use as a graduated neutral density filter was popularised by Californian adventurer, Galen Rowell (1940-2002). He had his own brand made by Singh-Ray in Arcadia, Florida which is still in business today. But the price of their filters really isn't any more comforting.
The one on the left was spotted on e-Bay selling second-hand for £53. But a new one, even if you got it from the world famous discounter B&H in New York City, a GND filter from Singh-Ray costs about $160 each!
So, it is a mature technology still in common use today yet the photographic market (you, me & everyone else with a camera) permits companies to charge eye watering prices for a plastic that's older than your granny.
As Tough As ... Cheese?
Maybe they are expensive because they are really durable? Well, despite the resin's high cost & military grade roots, after only occasional use & delicate handling, all my filters got badly scratched. Without a protective surface coating like RLX Plus®, they are prone to damage & I suspect that most of them don't have this feature because it can only be done in super clean rooms.
Too Busy To Notice
On the rare occasions when I did use them, some contre-jour shots were ruined by a purple/magenta colour cast on half of the image where the grey tones blocked out some of the light. And sometimes, I missed the shot entirely because I was instead, fumbling with adapter rings & an awkwardly stiff filter holder. So I quickly lost my patience & threw the whole kit in a box of scrap photographic parts where they lay for about a year.