Articles

Polarizing filters test

8. B+W Slim KSM C-POL MRC 72 mm

	B+W Slim KSM C-POL MRC 72 mm	Price: 479 PLN

B+W filters are manufactured by German Schneider Optics and definitely don’t belong to the cheapest ones. They’re covered by hard, thin MRC coatings which protect them against scratches. The respect of photographers, that these filters have, should go hand in hand with the highest quality. Slim polarizers allow us to work with wide-angle lenses without additional vignetting coming from the ring.

Results of the test

Transmission and extinction coefficient
- - - - - - - - - - - - - - - - - advertisement - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Red color extinction coefficient: 7.91E-4 - Score: 3/4 Green color extinction coefficient: 9.27E-4 - Score: 3/4 Blue color extinction coefficient: 2.41E-2 - Score: 0.5/4 Mean transmission of the whole spectrum: 34.74% - Score: 1.95/3 Score:	8.45/15
Flares
Without filter With filter Score:	7.5/7.5
Scattering
Luminance: 17 Score:	4.93/5
Vignetting
Edge darkening 3.3% Score:	3.72/5
Homogeneity
Without reservation Score:	5/5
Final score
Overall ranking: 1st place Econo-ranking: 7th place 29.6/37.5 pts (78.9 %) 0.34 pts

Usage

The ring turns smoothly, cleaning wasn’t too troublesome. The filter is well-made, it’s impossible to find fault with its construction. We get a cap in the kit.

Summary

1st place in the overall ranking
Similarly to other products of this manufacturer, the transmission of light of the azimuth parallel to the light is flat in majority of the visible spectrum. Pictures may have little warmer colors than in reality. The extinction coefficient of about 1/1000 is typical for most modern foil polarizers. The filter becomes transparent in infrared. We observe slight transmission of blue color, which should be extinguished. C1 and C2 graphs indicate that we’re dealing with a quarter-wave plate of zeroth order designed for the middle of visible spectrum. Well-deserved first place. No flares in the pictures, polarizer of very good parameters, top shelf components combined with precise workmanship (and reasonably high price).

The editorial staffs of lenstip.com have decided to award the filter with “The choice of LensTip.com” for being the first on the list of circular polarizers’ overall ranking.

Filter for tests was lent by Pstryk.pl