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Old Mar 22, 2006, 8:02 PM   #1
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I have a linear polarizer which I had purchased for my Panasonic FZ30. I tried it on my KM5D and the focusing and AE seem to work just fine. I have only tried it a couple of times, so far so good. Do I really need a circular polarizer if the linear seems to do the job? Also, aren't both types of polarizers supposed to belined upaccurately with the influx of light rays to attain theirfor the maximum effect?However, the lens, including the filter threat rotate a little to achieve the correct auto focus when the shutter is halfway pressed. That thenthrows off the axis of the polarizer. The only way around that is to then readjust the filter while keeping the shutter halfway pressed, correct? I am a little confused about this.
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Old Mar 22, 2006, 11:05 PM   #2
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I use a circular polarizer on my Minolta A1 a lot. My lens doesn't rotate, but I ususally check my polarizer several times while shooting to make sure the alignment is giving me the colors & performance I want.
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Old Mar 23, 2006, 1:59 AM   #3
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Old Mar 23, 2006, 4:35 AM   #4
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rduve wrote:
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I have a linear polarizer which I had purchased for my Panasonic FZ30. I tried it on my KM5D and the focusing and AE seem to work just fine. I have only tried it a couple of times, so far so good. Do I really need a circular polarizer if the linear seems to do the job? ...
Well, I think it's fair to say it does the job in a compromised way...

rduve wrote:
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... the lens, including the filter threat rotate a little to achieve the correct auto focus when the shutter is halfway pressed. That thenthrows off the axis of the polarizer. The only way around that is to then readjust the filter while keeping the shutter halfway pressed, correct?
As I understand it, this is precisely why circular polarisers are recommended for lenses that rotate. As Kalypso noted above, his A1 P&S has a fixed lens, ... my guess is it would work happily with a linear polariser, as well as a circular one.

I've never used a linear one, but AFAIK, linear polarisers are suited best to 'fixed' lenses, and circular polarisers to 'rotating' lenses.

I've read that linear polarisers have a stronger polarising effect than circular ones, so there may be a trade-off of strength vs convenience. Of course there are also multi-layered versions, just to make it more complicated :-)

You might like to take your camera into the local store and ask to try a circular polariser - see if it works more conveniently.

I've only recently started with SLRs, and have a Circular polariser that I find very useful. Hope that helps.



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Old Mar 23, 2006, 5:11 AM   #5
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Generally circular polarizers are required for dSLR cameras. This is not because the lens rotates, but because of the "Beam spliting" in the dsrl for focussing and/or metering. Linear ones may cause false readings.

For most non dslr cameras, like the Panasonics & others, linear polarizers are satisfactory, in fact they give a better effect.

Adjusting the polarizer alignment on a rotating lens will certainly be a frustration as rduve has experienced.
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Old Mar 23, 2006, 1:01 PM   #6
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Thanks for all your tips. I do not think that the circular polarizer handles the issue of the "rotating lens' since its axis still needs to be properly adjusted just like on the linear one.

Is the "beam splitting" technology employed in focusing and/or Auto Exposure? If it is a focusing issue I can always use manual focus?


I will try my linear polarizer some more this weekend and see how it works and maybe pick up a cheap circular one to compare the results. Will keep you posted.

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Old Mar 23, 2006, 10:09 PM   #7
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rduve: you are correct in that both Linear & circular polarizers need to be rotated for the best desired effect.

There appears to be much missinformation about linear v circular polarizers. For many years I used polarizers on my SLR film cameras. After getting a Fuji602 camera, I learned from photographic dealers/retailers that "Digital" cameras must use circular polarizers. In fact here in NZ most dont stock linears, as they consider circular to be universal. And that is true. They are also much more expensive.

The circular on the Fuji was disappointing, compared to the effects produced on the SLR film cameras years ago. I dont recall if that polarizer was a CP or LP, but as the SLR was not autofocus I suspect it was a LP.

I later learned that the circular requirement is for dSLR cameras, because they use beam splitting, & reflective mirrors (which can also polarise the light), for focus and/or metering. But for most non dSLR cameras the CP is not necessary, and so LP can be used without problems.

So I decided to search for a LP for the Fuji camera. It was not easy, but finally got one from an online site here in NZ. The results are much more pronounced than the CP on the Fuji camera. The comparison between CP & LP results using FZ20/30 were dramatically illustrated by a member on the Panasonic forum some weeks ago.

All this is not much interest for owners of dSLR cameras, as it seems the CP is recommended for those cameras.

An interesting site about this subject is:

http://dpfwiw.com/polarizer.htm#circular

Look for Circular v Linear, about 3/4 down the page.

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Old Mar 23, 2006, 11:01 PM   #8
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Well, I guess I will need to get a CP for my KM5D. Here, by the way, was a forum I startedwhere I postedsome shots taken with my LP (from Raynox) on my FZ30: http://www.stevesforums.com/forums/v...mp;forum_id=23
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Old Mar 23, 2006, 11:28 PM   #9
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Thanks rduve: That is exactly the thread I recalled. Well done. A comparison dramatically illustrated, and so you see I did remember it from December 05.

Sorry for rambling on here, as it is now obvious that you are very familiar with polarizers, but others may care to check out the link to your Panasonic thread.

Cheers.
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Old Mar 24, 2006, 1:48 AM   #10
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News Flash! My linear polarizer works perfectly fine on my KM Maxxum 5D. The camera focuses swiftly and accurately with it. So, I see no need to get a circular one, regardless of what people might say.
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