Camera filters - circular polarizers and _that_ test

[anoobis]

I started looking for a (67mm) polarizer and, of course, the lenstip test and its addendum (http://www.lenstip.com/119.1-article-Polarizing_filters_test_-_supplement_Introduction.html) litter the forum suggestions; fairly so, as I've not found anything else that directly and objectively compares a large collection.

I would, however, welcome some advice on interpreting the results and analysis. I think the main questions are:
i) what are the real world effects of difference in the properties tested?
ii) have any important properties been missed?

For instance, the transmission and extinction charts are given the largest weighting. This seems reasonable. However, the analysis based on the averaged numbers is not entirely straightforward.

Let's compare the Marumi DHG and Hoya HD. These both achieve 9+ with the Marumi coming just ahead. Yet, the Hoya has one of the flattest curves in the test. This indicates to me that it should preserve colour well. It is let down at the extremes; at the red end the transmission falls rapidly, whilst at the blue end, the extinction rises within band. The Marumi on the other hand displays significant transmission variation across the spectrum. It also blocks more light.

To my mind, so much is encompassed in the single reported number that it is unhelpful.

Have I misunderstood this test? Are the effects significant?

I also find it interesting that the top ranked B+W, arguably the most respected brand in the test, did worse on the chart test.

Clearly I need some guidance as to what makes a good filter here!

FWIW, my other research indicates that the properties of the Hoya HRT are similar to those of the HD (including percentage transmission) but that the HRT is marketed at a lower point and the HD may be more robust.

Any thoughts?

 

[anoobis]

^^

 

[StudioSound]

Being spectrally neutral seems like a very important aspect of a polarizer, and I would buy the Hoya HD filter based on the data provided - it seems considerably better than the others tested.

It does seem odd the way they weighted their results, as they don't seem to give that much importance.

 

[leftnose]

In the past, I used Hoya filters almost exclusively but I am switching over to B+W F-Pro MRC filters mostly because they are infinitely easier to clean. Hoya HMC and SHMC filters streak like crazy and take forever to clean.

Also, the review you posted doesn't include B+W's top of the line filter which is the competition to the Hoya HD filter. You need to look at the B+W XS-Pro KSM MRC Nano. That's the polarizer I have and it's really good. No color cast, well built, and robust with a sealed polarizing foil for long life.

 

[StudioSound]

In the past, I used Hoya filters almost exclusively but I am switching over to B+W F-Pro MRC filters mostly because they are infinitely easier to clean. Hoya HMC and SHMC filters streak like crazy and take forever to clean.

Not a problem for the HD filters:

 Put your thumb on one, and the fingerprint just doesn't stick. If you go out of your way to get fingerprints on it, they clean right off, too.

This has been the biggest problem with multicoated filters: they are easy to get smudged, and tough to clean. These new HD filters really are very different.

You need to look at the B+W XS-Pro KSM MRC Nano. That's the polarizer I have and it's really good. No color cast, well built, and robust with a sealed polarizing foil for long life.

Do you have data for that? All I can find on the site is information about their MRC coating, and nothing about their transmission.

 

[Redcarmoose]

Nice to see a post about the importance of polarizer use. There seems to be a trend that people think digital manipulation bypasses the importance in photography.
 
I use a glass Nikon polarizer, and amazingly if the angle of spectral incidence on water is just in the right place, you can see into the water and see the bottom of the ocean, with the polarizer filter. No photoshop will remove the spectral highlights. To a degree this is also the case with sky clouds.
 
I'm using an old linear and don't see the secondary linear light passing causing an issue with my sensor. Let us know what you end up with and how it works. I'm in the market to get one for my 18mm prime.
 
 

 

 
Both of these applications are hard to do post.

 

[leftnose]

http://www.kenrockwell.com/hoya/hd-filters.htm 
Put your thumb on one, and the fingerprint just doesn't stick. If you go out of your way to get fingerprints on it, they clean right off, too.

This has been the biggest problem with multicoated filters: they are easy to get smudged, and tough to clean. These new HD filters really are very different.

 

 
You'll have to forgive me if I dismiss Ken Rockwell as a credible source.  
 
Quote:

Do you have data for that? All I can find on the site is information about their MRC coating, and nothing about their transmission.

 
Data on what, the neutral color cast?  My own A/B testing checking white balance, color temperatures, etc. in different environments and lighting conditions.  I can tell you anecdotally that the MRC and MRC Nano coatings are definitely different as they are a different color.

 

[anoobis]

Thanks for the responses guys, appreciated. I had to put this on the back burner but hopefully will get a chance to revisit it soon.
 
The comment about the top end B+W (not in the test) being a competitor to the Hoya HD is interesting; in that case it seems the Hoya HD is a good buy.
 
I'm keen to try out removing reflections with a polarizer. As the phone picture shows, it's effective and much simpler to do when the photo is taken.
 
I'm still unsure about the measurements and neutrality. Maybe they just picked bad metrics. Or, maybe none of them are particularly neutral? Have you found yourself wanting to post-process because the colours aren't quite right anyway?
 
Given the photos can look so different with the filter anyway, maybe it shouldn't be a concern.
 
At the moment I'm leaning towards a Marumi (anecdotally cool cast) or the Hoya HD (anecdotally warm cast), though that could change!
Would the fact that the Hoya HD has anomalies at both ends put you off?

 

[anoobis]

Without more understanding of the lenstip measurements (e.g. what is C1, C2?) I'm becoming skeptical of their rankings (at least based on the results presented). I still think that the transmission charts are important and you have to be very careful of the different scales that are presented. The Hoya HD is marked down because of the red extinction coefficient. When I checked, it would seem that 750nm is in the visible/IR boundary region, yet the review has taken values up to 780nm. I'd argue the Hoya HD is fine where you need it. I've seen nothing to suggest that aiming for the flattest frequency response is the wrong interpretation. I did see one comment that lenses with large apertures tend to be more expensive, why would you then want to opt for a lower transmission filter (ND aside)? I think that's a good point. So I think I've settled the Hoya HD (flare seems okay though difficult to tell with the lighter background in the supplementary test). I will do another round of price checking; it's difficult to shrug the rankings in the test but I don't fully agree with their weightings.
 
 
Edit: apologies for (lack of) formatting. It didn't look like that when I typed it!

 

[leftnose]

You're over thinking it.  Any of the top filters from the top brands, whether Hoya, B+W, Marumi, or Heliopan, or whatever will work just fine.  Just stay away from the $30 Wolf Camera special.

 

[Redcarmoose]

They can totally scratch too causing a loss of image quality. Care and maintaining a scratch free polarizer is a top concern I would think.

 

[leftnose]

BTW, I just noticed that your considering a 67mm filter.  I might go with a 72 or 77 and some step-up rings.  In the future, you may buy a new lens with a bigger front elemetn and you don't want to end up having to buy another polarizer.  While there are a few 82mm lenses out there, my polarizer is 77mm and it, with 4 different step-up rings, cover my needs just fine.

 

[anoobis]

Different sizes, that's over-thinking it
 
No, it's a fair point. I can't see me buying lenses with a larger front element any time soon; I'd suspect the price of a filter would be dwarfed by the lens price so it's not much of a concern. 67mm is the largest lens I own, so I'll get adapters up to that.
 
Looks like it's the Hoya HD then (HD2 appears to be USA only).

 

[Seavan]

This is funny I came across this thread on head-fi. I will be putting my B+W KSM C-POL MRC on ebay tomorrow. PM me if you are interested.

 

[anoobis]

I thought I'd just follow up with some test shots. It's taken a while, as weather and spare time have conspired against me!
 
Quick question before the images; presumably the filters are designed to have lens cap attached? It's very slim an I was unsure whether the cap would be pushed onto the glass.
 
I've not been careful with exposure, or anything else for that matter! Just a case of trying to observe the effect. Actually, in some cases, I struggled with the setting through the viewfinder
 
 

 
Water seemed a _lot_ cleaner a few days earlier!

 
The brighter picture is with the polariser; you can see more highlights on the second version.
 

 

 
That's one interested duck! Not sure whether one's better than the other but they're certainly different.

 

 

 
No idea how good a job the filter's done but it seems okay.