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12-23-2012, 08:41 PM   #1
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Huge Price Difference For Circular Polarizers

I'm looking at circular polarizers for my 600mm Sigma mirror lens, and and perplexed by the wide price differences. I know that any filter with an 86mm thread is going to cost a few bucks, but the range I am seeing is ridiculous.

At the bottom end of the scale is around $25, and I have seen some at around $500. Now I realize there will be some differences in glass quality, and some may have more coatings than others, but the ads at the various camera suppliers are less than informative.

And I really would have a hard time spending almost twice as much for a polarizer as In did on the lens.

12-23-2012, 08:56 PM   #2
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QuoteOriginally posted by Racer X 69 Quote
And I really would have a hard time spending almost twice as much for a polarizer as In did on the lens.
Then spend half as much! Price doesn't precisely equal quality in filters, but your chances that the $25 86mm CPLs are garbage is pretty high. Of course, the "bargain line" from some well-known makers (Hoya, I'm looking at you) are also garbage...

The Sigma cat 600 is a pretty sharp lens that needs lots of light to focus, so you'd be well served getting a good, slim, low-density (not too dark) polarizer to preserve the qualities of the lens behind it.

BTW, you should check whether your filter thread is "standard" 0.75mm pitch, or the larger 1.00mm pitch that lots of 86mm filters come in (not sure why this is, but my 6x6 Zeiss lens is 86mm/1mm pitch, yet I have 110mm filters that are 0.75). This slight wrinkle to 86mm filters in particular is another reason to get a known-brand filter or one that has plenty of information provided, so you don't end up with a filter you can't screw onto your lens!
12-23-2012, 08:56 PM   #3
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Doesn't that mirror take a small filter on the back end of the lens?
12-23-2012, 08:59 PM   #4
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You could almost certainly get by with a linear polarizer. AF is not an issue for your application. With less stuff inside, don't linear polarizers pass a little more light? That has to help at 600mm f8.

If you still have a plan to fix the filter carrier, a good brand can be resold. In that case buy the circular because people will want to make sure it works with their new lens.

You could also make some cardboard rings and see how much smaller you can get the opening without vignetting. Maybe you could work down to a more affordable size if you're only using the lens on APS-C.

12-23-2012, 09:28 PM   #5
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QuoteOriginally posted by panoguy Quote
Then spend half as much! Price doesn't precisely equal quality in filters, but your chances that the $25 86mm CPLs are garbage is pretty high. Of course, the "bargain line" from some well-known makers (Hoya, I'm looking at you) are also garbage...
So true . . .

QuoteOriginally posted by panoguy Quote
The Sigma cat 600 is a pretty sharp lens that needs lots of light to focus, so you'd be well served getting a good, slim, low-density (not too dark) polarizer to preserve the qualities of the lens behind it.
Excellent point.

QuoteOriginally posted by panoguy Quote
BTW, you should check whether your filter thread is "standard" 0.75mm pitch, or the larger 1.00mm pitch that lots of 86mm filters come in (not sure why this is, but my 6x6 Zeiss lens is 86mm/1mm pitch, yet I have 110mm filters that are 0.75). This slight wrinkle to 86mm filters in particular is another reason to get a known-brand filter or one that has plenty of information provided, so you don't end up with a filter you can't screw onto your lens!
Thanks for the tip on the thread pitch differences! I'm gonna run out to my shop and grab a thread pitch gauge right now.

QuoteOriginally posted by Docrwm Quote
Doesn't that mirror take a small filter on the back end of the lens?
Yes it does, but it is kinda hard to turn the CPL filter when it is inside the lens.

QuoteOriginally posted by Just1MoreDave Quote
If you still have a plan to fix the filter carrier, a good brand can be resold. In that case buy the circular because people will want to make sure it works with their new lens.
For the moment I am just slipping the part with the handle in the slot so light doesn't leak in. I'm still weighing my options there. Someone here offered to machine one on a milling machine, but thought the threads would be tough to replicate. And I still haven't abandoned the idea of making one using plastic resin and the lost wax casting process.

*sigh* Planned obsolescence sucks.
12-23-2012, 09:46 PM - 1 Like   #6
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QuoteOriginally posted by Just1MoreDave Quote
You could almost certainly get by with a linear polarizer. AF is not an issue for your application.
Dave...I was very surprised to find out just this last week that AF is only part of the linear vs. circular polarizer equation. The general issue is with the half-silvered mirror used by the AF system. The amount of light reflected will vary according to the plane of polarization. As a result, the amount of light hitting the meter sensors may not be the same as that hitting the digital sensor or film. In other words, the metering is no longer reliable.

I know, it sucks.


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12-24-2012, 12:57 AM   #7
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There is another factor in those extreme high priced polarizers--Kaseman Type. You'll find Kasseman spelled differently in different product catalogs and it's a different variety of polarizer. I have owned both B+W and Heliopan Kaseman Circular Polarizers, currently own three sizes and recommend them highly.

The main difference for my field use is that Kaseman variety circular polarizers are edge sealed for extra durability in humid conditions and in cold conditions...conditions that could risk fogging between layers. This certainly is a factor in rainy or wet conditions too and for higher end weather sealed lenses may make sense in the total weather-ability of your kit.

Since polarizers are made from a sandwich of polarizing foil between two layers of glass, having edge sealing would seem to be a logical upgrade.

Also, the two brands of Kaseman polarizers that I mentioned above use cut glass for both surfaces rather than molded glass. This assures more precise plano-parallel design and with 4 total glass surfaces in a sandwiched polarizer any imperfections in the flatness of the glass are quadrupled.

In addition, the polarizing foils selected for Kaseman type filters are claimed to be of higher precision and quality than "ordinary" foils. Not sure what specs. are measured to determine polarizing foil quality?

There are polarizers marketed with newer "faster" foils in several brands--from Kenko on the low end to B+W on the high end--that pass light more efficiently and may be of better quality than older standard foils? Though I have recently acquired a Kaseman variety faster polarizer (B+W), I haven't had sufficient experience with it to pass judgement.
12-24-2012, 06:29 AM   #8
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I suggest folks read Lenstip.com's review of CPL filters before just buying based on name or price.

12-24-2012, 02:29 PM   #9
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Yeah, just look for the relatively affordable Marumi CPL and you should be fine.
12-24-2012, 05:02 PM   #10
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QuoteOriginally posted by msatlas Quote
Yeah, just look for the relatively affordable Marumi CPL and you should be fine.
They do rank as high or higher than many of the most expensive CPL filters out there. I am fond of the Marumi filters I have, they are easier to clean than the others and their test results indicate they are top performers.
12-24-2012, 07:23 PM   #11
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Hello Racer, I have the same Sigma 600/8 in like new condition for CAD $ 75 ex Craigslist Toronto. Now I am not going to to spend $ 500 to buy a CPL for a $ 75 lens.
So I bought the cheapest Glass CPL & ND filter in 86 & 30 mm off evil bay with free shipping from China. Excellent build & quality. Perfect photos too. After all the %-age of time one would use this filter just does not justify the cost as one would again use the Sigma Mirror Lens hardly a few times in a year.
I got the 30 mm filter ground by an optician to fit the rear filter holder. What great results.
Regards. Bipin.
camp: Thornhill, Ontario, Canada.
12-24-2012, 08:14 PM   #12
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Wasn't the Lenstip review the one done in the dark shooting at streetlamps and that didn't measure distortion at all (which is important with 4 glass surfaces on two chunks of glass)? Shooting at streetlamps severely limits the color spectrum being analyzed since it isn't sunlight but the specific color of the lamp.

Realistically, we should all use polarizers that are built with a similar quality as the lenses they are placed on.
12-24-2012, 10:33 PM   #13
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I suppose the best answer to the OP is to try the $25 CPL and see if it does the job. It might be fine or it might be a piece of junk. I can understand not wanting to spend a lot on a filter for a used lens. Good ones aren't cheap. My 49mm B&W CPL cost more than some of the lenses I use it on but since I have several lenses that take that size, it was worthwhile. I have picked up several used filters through the years, usually included with a used camera or lenses and some have been acceptable. 86mm isn't too common so used isn't an item you are likely to find.
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