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01-12-2013, 02:38 PM   #1
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polarizing filters

Greetings,

I'm slowly getting "comfortable" with digital gear. However, I have two older manual focus Pentax lenses. I ordered several polarizers from Adorama. They came, they are great, but they are all circular, not the "regular" kind. I actually don't think there are many "regular" versions left on the market.

Question - Does using a circular polarizer on a manual less decrease the effectiveness of the filter? I just realized that whenever I'm outside, even though I now make use AF, I still manually adjust my filter. (Old habits die hard...)

I'm rather fierce in my use of polarizers. I immediately put them on all my lenses, both film and digital...and leave them there. Over the decades they've made good pictures even better. Just recently (using my K100 with a circular polarizer) I was asked to compare my shots of a new building with several other photographers. My shot was picked, not because I'm "a great photographer," but because my filter made the sky and the clouds look spectacular.

But...using a wonderful (and inexpensive) manual focus lens...does it matter which sort of polarizer I use?

Thanks again for any and all suggestions.

01-12-2013, 02:56 PM   #2
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As I understand it, linear polarizers (the old fashioned kind) interfere with some auto-focus systems. I have also seen posted here that Pentax AF works fine with linear polarizers. Circular polarizers started to be used when cameras went to AF systems.

But to answer your question you can use a manual lens with either kind, it makes no difference. The only potential problem is interference with the AF system which is not your issue. I have both and have used both on my k-5 but only with manual focus, never tried a linear one with auto-focus. Usually I'm shooting water falls when I use the linear as it fits my cokin system and I manually focus doing that anyway.
01-12-2013, 02:57 PM   #3
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I think it does matter. CPLs work better, from all I have read, with the sensor arrangements than do the old linear PL filters. Try this one, but remember that your camera has its metering system set up in a way that CPLs work best with it, not simply the AF system. If you are going to meter on your own and not rely on the camera metering then an old LPL filter is fine, otherwise a CPL is the way to go.
Photography 101.org - Lens Filters Explained
01-12-2013, 04:18 PM   #4
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put 2 circular polarizers together and adjust to achieve a big stopper ND filter

01-12-2013, 04:50 PM   #5
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filter always degrade the sharpness of the lens but a pol often adds something to the image so outdoors it certainly is not a mistake to use them.

As for linear, AF works good enough but with the metering they can be a stop off.
01-13-2013, 03:49 PM   #6
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Thanks! Yes, "linear" was the word I could not remember. As I mentioned I put on polarizers, and just leave them. I'll have to try the suggestion - two at a time. Curious...There is a link above to Photography 101.org. The first before and after example shows a street with clouds in a blue sky. That's exactly how my shot compared to others of a new public service building. Mine appeared in a local PR sheet. Again, not that I was such a great photographer; but I was using the appropriate filter.

By the way, I just acquired a used SMC 100mm F3.5 macro lens. It was from a neighbor, and he only wanted $125 for it. It's a wonderful lens. I feel a bit guilty...like I maybe stole it from him...

Thanks again. All my lenses, including the 100mm, currently have circular polarizers.

I'm starting to have moments when I think this digital stuff could be fun.

Old Film Guy
01-13-2013, 07:32 PM   #7
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QuoteOriginally posted by Old Film Guy Quote
Thanks! Yes, "linear" was the word I could not remember. As I mentioned I put on polarizers, and just leave them. I'll have to try the suggestion - two at a time. Curious...There is a link above to Photography 101.org. The first before and after example shows a street with clouds in a blue sky. That's exactly how my shot compared to others of a new public service building. Mine appeared in a local PR sheet. Again, not that I was such a great photographer; but I was using the appropriate filter.

By the way, I just acquired a used SMC 100mm F3.5 macro lens. It was from a neighbor, and he only wanted $125 for it. It's a wonderful lens. I feel a bit guilty...like I maybe stole it from him...

Thanks again. All my lenses, including the 100mm, currently have circular polarizers.

I'm starting to have moments when I think this digital stuff could be fun.

Old Film Guy
Is the lens you got this one - SMC Pentax-FA 100mm F3.5 Macro?

If so you got it for a good, but not criminally good , price.
01-13-2013, 07:43 PM   #8
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I'm not sure a polarizer is as important as it was in the film era. I've primarily used them for foliage, to cut reflections from leaves, and they're still useful for that. For water I sometimes use a polarizer adjusted for only partial effect, because adjusting for full effect can leave the image flat by killing essentially all the reflections, to a degree that doesn't look natural.

With skies, digital gives you at least some ability to adjust color/brightness/contrast, l as long as you don't blow out the clouds. And you can adjust those factors across an image shot with a wide angle lens, say 100degree, which a polarizer will sometimes have trouble with.

While I'm not a big believer in image degradation from even budget UV filters, polarizers have more glass surfaces, and stacking them makes even more than that. So, combined with the slower shutter speeds you'll get from using a polarizer, you can definitely have some image degradation from using a polarizer. Even with your camera tripod-mounted, with moving subjects - like foliage that's moving from the wind.

So, blanket use of a polarizer is probably not the best idea for everyone, but apparently it works for you.

Paul

01-13-2013, 08:58 PM   #9
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QuoteOriginally posted by Old Film Guy Quote
By the way, I just acquired a used SMC 100mm F3.5 macro lens. It was from a neighbor, and he only wanted $125 for it. It's a wonderful lens. I feel a bit guilty...like I maybe stole it from him...
That's a fair price for that lens. And it is a handy little macro lens. Had one for awhile until I got the D FA 100mm f/2.8. I think I paid about $100 for it and sold it for $130.00
01-15-2013, 10:58 AM   #10
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I find the improvement that polarizers can provide by cutting some glare can be worth the "degradation". As it is, I've generally only seen degradation when I am working with multiple filters. One filter, generally doesn't cause issues. As for linear vs. circular, I've not really had any problems with my Pentax cameras and a linear polarizer, although I only have one. I do like linear polarizers better as I find they are more effective at cutting glare, but that can also be unnatural (as others alluded to) if you get too crazy with it. The stop or two lost, isn't usually a big deal to me because I'm usually using such a lens when it is bright and sunny out.

Last, I find the biggest issue with polarizers occurs when shooting at wide angles. With a wide field of view, it isn't unusual for a polarizer to cause a gradient across the sky as it works in one portion but not the other due to the angle of the sun and the angle of light hitting your lens. In those cases, it is a bit better to drop the polarizer completely.

The only other use for polarizers that I advocate is indoors at museums or when shooting through glass in general. They can help cut reflections and glare that occur when shooting items through windows. In those cases, the exposure loss can be an issue, but reflections and glare can degrade an otherwise nice image.
01-16-2013, 06:03 PM   #11
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I agree that leaving a CPL - or any PL - on all the time is not a particularly good idea. On a wide or super-wide angle lens, the CPL will often cause variations in sky color that can't be corrected in post. Also, a CPL really only works properly when shooting at right angles to the sun anyway so when shooting against the light for a back-lit subject or with back to the light, a CPL is useless.

I use CPLs regularly but only when the situation and particular scene call for it.
01-24-2013, 10:20 AM   #12
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CPL Lubrication?

I recently picked up a used Vivitar Series 1 CPL for the 18-55 kit lens to try out. It's a little stiff to turn, but with the petal hood on and the little "door" open, it's just about impossible. Is a safe way to lubricate these?
01-24-2013, 11:21 AM   #13
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QuoteOriginally posted by rlg118 Quote
Is a safe way to lubricate these?
Whoa, probably not? Maybe you can soften it up a bit if you take it off the lens and just spin it around a little. The filter being tough isn't a bad thing, though, since otherwise stuff can get inside it and it can fog up. Happened with a cheapo cpl of mine.
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