B&W circular MRC slim polariser

Started Apr 19, 2010 | Discussions thread
Legion5
Senior MemberPosts: 1,047
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Re: B&W circular MRC slim polariser
In reply to copejorg1, Apr 21, 2010

copejorg1 wrote:

Legion5 wrote:

copejorg1 , you'll notice that the lenstip test is poorly designed, it puts heavy weight on blue frequency polarizing. The weight on this blue polarizing is arbitrarily extremely exponential and differences of several points in this polarizing score will be indistinguishable, so while the Marumi does rate the same as the B+W, in reality there is a slight difference in blue light polarization which is indistinguishable (in favor of Marumi), and a visible, distinguishable difference in flare (in favor of B+W).

You say their test is poorly designed, but then quote their test result on the flare comparison, where it suits your agenda to do so. It seems you don't really have a problem with the tests themselves -- only with their interpretation (weighting) of the results. That's your business, of course -- but it doesn't mean it's a poorly designed test.

Correct.

Furthermore the test does not rate color reproduction, the Marumi filter distorts colors in a non-linear fashion, and significantly and extremely more so than the B+W and it and almost every other filter are horrifying in this regard.

Strong words. Got any examples you could post, to illustrate these "horrifying" color distortions that you contend are inherent to all non-B+W polarizers?

I didn't say all, I said almost all, it's B+W and Sigma actually, but Sigma does worse in flare.

The color reproduction is the red line. Keep in mind that fully visible light to humans is 425-665nm after that light intensity falls off at 400-700nm.

My trade is in figuring out cheap alternatives, I work with megacorporations on this, ...

Sounds impressive. But having worked as a value analysis engineer myself, I think it's safe to say I'm not quite as impressed with that as you probably want me to be ...

Well, either way it's nice to have some one with your way of thinking around.

... and it would be nice to think that the big expensive brand name is easily beaten but the fact is that B+W is the industry leader, they design their filters in unique ways that the competition does not and are more through and successful in their designs and make products which work better in the real world. Other manufacturers simply slap the best materials together and call it a day. B+W engineers their product to simply be the best.

So, is that why the workmanship of both the B+W KSM C-POL MRC and the B+W C-POL MRC filters that finished 3rd and 6th, overall, in the lenstip.com test were criticized as follows?:

B+W and Heliopan are brass filters, brass is a soft metal which in machining is known as a "gummy metal". This makes it good at both getting stuck and unstuck. In the real world it's less likely to get stuck in harsh conditions but only slightly more annoying to use day to day, I'm not annoyed by mine. The review theorizes that these would be more likely to seize under harsh conditions because of the way they sticks in day to day operation, the opposite is actually true and they are comparatively better. In this situation the perceived workmanship issues are not oversights but a design feature.

If you'll notice B+W Slim filters were the ones that provided even resistance according to the review. According to B+W "for manufacturing reasons, the Slim Circular Polarizer is only offered in an aluminum mount.". The use of aluminum resulting in the preceived issue disappearing makes it obvious the effects were a function of the material.

"The ring turns with unequal resistance , quite hard. This resistance may turn out to be large if the filter is used at low temperatures and we turn it through a small lens hood window."

Kind of makes me wonder which manufacturers are really just slapping the materials together, and which ones are actually keeping their eye on the ball. Of the 24 filters evaluated in that test, only those two B+W filters, and the two very expensive Heliopan models, were criticized for having a ring with uneven turning resistance.

If it helps, it turns out that Heliopan which is often compared to B+W in price and target market is near the bottom of the ladder.

I don't know that it "helps", per se, as I don't really have an agenda here. But a lot of people already realized that Heliopan products are overpriced junk, using jacked-up pricing as a marketing ploy to impart an impression of quality that isn't really there. Not the first time anybody's pulled that stunt, which is why the value analysis function (done well) is so important to companies wanting to spend their money wisely. As you know.

Agreed.

It would be a mistake to use anything but a B+W polarizer due to significantly worse color reproduction issues, especially on a lens this expensive.

Again, I await your comparative sample photos, demonstrating that assertion for everyone to see.
--
Greg

I've decided to spend some time making examples, I used photoshop's exposure function to simulate light transmission. Because 1 stop of exposure = 50% less light, you can convert the percentages in the lenstip test to EV steps by the function Percent = 100/(2^EV).

Comparison:

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