Monday, August 23, 2010

Shedding Light On Polarising Filters

Shedding Light On Polarising Filters



Well after doing a lot of surfing and gleaning information from many helpful people on POTN, I think I can now give back this info in one thread. Hopefully this will reduce the confusion for the next person who tries to research this subject.

So, you've purchased an ultra wide angle lens for your DSLR and you would like to buy a polarizing filter for it? Unless you've been down this path before, the many brands and models are extremely confusing. The questions of whether or not to go with warming, Kaesseman, slim, circular, linear, graduated... etc etc just makes it worse.

The major thing that everyone seems to be in agreement with, is that you should buy a good quality filter. "Don't put a $10 piece of junk on your several hundred (or thousand) dollar lens." The brands that I have read through many forums and reviews which have been recommended include B+W, Hoya, Heliopan and Kenko. I'm sure there are many others, but they seem to be mentioned by lots of people as being quite reliable.

The other agreed points are that with auto focus in digital cameras, you need to get a circular polariser; the linear polarisers can interfere with the autofocus. Also a filter with "multicoating" is a good idea, as these can be more effective in preventing lens flare (coupled with your lens hood of course).

The first big issue with ultra wide angle lenses and polarisers (possibly other filters too, but I did not research them in any detail) is the possibility of vignetting. From my understanding, this is because the lens is so wide, it perceives the shadow of the edge of the filter. (I'm sure someone will correct me if I'm way off base.) This is where the first debate begins: how wide a lens can we use a polariser on before this problem begins to occur? ie: Which lenses cause this concern; 10-22mm... or maybe the 12-24 lenses? AND does having different lens factors (ie 5D full frame vs the Rebel's 1.6) have a further effect on this issue? I don't know the answer, as there were many theories out there. Hopefully someone will test this theory. (or they already have and I just couldn't find them!)

The next part of the debate is whether or not a "slim" filter design is required. These are filters that are lower in profile, thus creating less of a "lip" out from your lens- and hopefully less vignette. They are generally more expensive than their "regular" counterparts.

Many of the slim filters out there have no front thread, which means you cannot stack lenses (which is debatably not neccessary anyway... more about that later) and more frustratingly, (for me anyway) you can't attach your normal clip-on lens cap. All of the filters with the no-front-thread-design that I looked at, provided you with a plastic slip-on cap. Reportedly, they don't stay on very well (I remember my G2 had one and it was constantly falling off- but it also had a safety cord) and are easy to lose. Many people have spoken very favourably of these filters and were able to tolerate the lens cap issue. One possible solution, is to have a lens cap saving device attached- basically a little plastic "dot" that sticks to the lens cap and then is attached to the lens via elastic. I've got one on my kit lens; very cheap to buy.
http://www.amazon.com/gp/product/B00...lance&n=502394

Just to give a comparison here (all filters quoted in 77mm):
The B+W 77mm Circular Polarizer (MRC) Multi-Resistant Coating Glass Filter is $144.95 at B&H.
The B+W 77mm Circular Polarizer (MRC) Multi-Resistant Coating Glass Filter Slim is $164.95.

Another filter type that was thrown into my selection pile, just to create more confusion, was the Kaesemann. As per B+W's blurb: "Kaesemann ("encased") filters are completely edge-sealed for maximum durability under extreme climatic conditions." Some of the other filter manufacturers (Heliopan for example) also make Kaesemann versions of their filters. One of the generous people on here suggested to me that it was a bit of overkill purchasing this for normal landscape/travel photography and I agreed that the extra cost wasn't worth it to me. Others might find the extra protection useful. FYI:
The B+W 77mm Kaesemann Circular Polarizer Glass Filter is $164.95 at B&H; and
The B+W 77mm Kaesemann Circular Polarizer Glass Filter Slim is $174.95.

Two other options I was able to find, was the "Moose" filter. http://www.moosepeterson.com/gear/moosefilter.html (also available on other vendors' sites) and the Hoya or Kenko Pro 1 filters.

The Moose filter (made by Hoya for a nature photographer) is a combined "warming" filter and polariser which has a front thread. The disadvantage is that if you don't want the warming effect, you can't separate it from the polariser. (For an explanation on "warming", check out the link above.) The other thing I could not find any literature on, was whether or not this filter is multicoated. If it is, then it could be a decent buy, because it "works on any lens up to 17mm and WILL NOT VIGNETTE regardless of which f/stop is used!" (quote from his site). Ah!- only 17mm. This filter still remains a bit of a mystery to me. The creator raves about it (as he would of course), but uses a Nikon D2X (1.5 crop factor) and lists the Nikon 12-24 as one of his lenses. Maybe he doesn't use his polariser below 17mm. Anyway, I wasn't able to find many reviews out there about his filters, but at $118.50 from B&H or $99 direct from his site, they're worth investigating further. As I had to make a decision tonight and make my purchase, I left it up to others to "run with the ball" if they're interested.

Now, onto the Hoya & Kenko Pro 1's...
These two are both slim filters, but they also have a front thread! condyk suggested the Kenko to me as he (and from many other resources out there online) believes that Kenko and Hoya are one and the same... and Kenko is cheaper. Unfortunately for those of us in the US of A, it seems that the Kenko Pro 1 is marketed here as "Hoya Pro 1" and marked up considerably. As far as I was able to figure out, the same filter is marketed in the UK, Hong Kong and Australia as "Kenko Pro 1". This info could be wrong, but all evidence I've been able to find points in this direction. FYI:
The Hoya 77mm Circular Polarizing Pro 1 Digital Multi-Coated Glass Filter is $194.95 at B&H.
I then found the Kenko on the link below for $108.95AU (approx $80USD):
http://cgi.ebay.com.au/Kenko-77mm-Pr...QQcmdZViewItem

Again, I cannot categorically say that these are the same filter, but if they are, then perhaps people with more time and patience than me could ship them over. Alternatively, if you live somewhere where the Kenko is available, lucky you! I read many favourable comments about the Hoya Pro 1, so taking everything above into account and unable to find someone who had actually tested the Tokina 12-24 with a normal sized polarising filter, I chose that one. FYI, I was able to get it from:
http://www.2filter.com/hoya/hoya_pro1_digital.html for $156.86 (normally $194.63). One of the forums I was browsing through pointed out you need to actually click on "order" to reflect any discounts they might have at that moment.

I was able to find one person who tried a normal sized UV filter on his 12-24, and apparently didn't experience too much of a problem with vignetting.
http://www.fredmiranda.com/forum/top...5396/0#2756574
Still not 100% convinced, I still bought the Pro 1. I would love to hear about peoples' actual experiences with any of the ultra wide angle lenses and these filters. The easiest thing of course, would be to walk into a shop and try this out, but none of the shops in my area stock anything!

One final note, I was really interested in ND graduated filters and started looking into those as a possibility. A pro pointed out to me that with digital, the only thing you can't duplicate in Photoshop (or similar software) is polarising. I found a fantastic tutorial for duplicating the ND graduated effect in Photoshop here:
http://www.fredmiranda.com/article_2/ I've been experimenting with it and it's fantastic! Many different effects, normally achieved through a filter (like warming for example) can be achieved through software- so save your dough for a good polariser!

Hopefully this dribble helps someone. I apologise if any of this is incorrect; I am by no means a professional and my intentions are only to prevent someone from going through the confusing headache I did. Maybe if there's anything to add or amend here, it could be made a "sticky" down the track; especially when some people have provided feedback of their own personal experiences. There are other variations on the examples of basic polarisers I mentioned and they can be much more expensive. I just focussed on the ones under $200 and went from there

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