I'll voice a dissenting opinion.
Filters are fetish objects. I don't think you can buy an optically inadequate filter. .
False. You can buy single-coated filters which have about 7% reflectance and transmit only 93% of the light that should pass thru them.
You can buy multicoated filters, which pass 97% of the light that should pass thru them.
You can buy 'supermulticoated' filters which pass 99%+ of the light that should pass thru a filter.
Back in 2012 I posted this, on the topic...
"The old HMC filters transmit 97% in a 8-layer formula....The Pro1 D's are cheap crap. Don't waste your money on em.
Hoya's web site is rather non-specific about specs on the Pro1 Digital coating DMC. Per this site
http://photofilter.com/hoya.htm
the SMC filter 7-layer coatings are effective to 99.7%. "Hoya HMC Camera Filters feature 3 layers of Multi Coating applied to each side of the filter, average light transmission is over 97%
Hoya SMC Camera filters have 7 layers or multi coating applied to each side of the filter
average light transmission is over 99.7% Works great with your Digital Camera"
This web site has similar information about SMC filters
http://camerafilters.net/hoya.htm
Both web sites lack transmission information about the Pro 1 Digital filters, just as Hoya's own web site lacks that information.
The first post here
http://www.fredmiranda.com/forum/topic/680035 shows SHMC > DMC > HMC in terms of resisting flare."
This filter comparison, in a test performed many years ago, proves my points above...
Look at the test for the Tiffen filter in high flare conditions, and compare the results to the multicoated filter low flare.
I once had a Tiffen polarizer. If you looked thru the filter as you rotated it in your hand, it was readily apparent that the filter acted like a prism, bendling light off to one side and distorting the image seen thru the Tiffen...I crushed it under my heel rather than ever sell it off to some innocent buyer!
BTW, I agree with the rest of your comments in that post...just not the blue text.