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03-18-2018, 01:42 PM   #16
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QuoteOriginally posted by amoringello Quote
There is no reason to not use linear polarizers. I don't know where or why the myth was started about circular polarizers being necessary to prevent issues with focusing and/or metering.
...and yet you go on to say...
QuoteOriginally posted by amoringello Quote
Perhaps it had limited truth a decade+ ago, but it is just not the case with current cameras. At least I have yet to see any influence, and have yet to hear of anyone who has been able to provide actual first hand experience of such affects.
I just tried it, with a K1, a 55-300 and a linear Hoya and no-name CPL. The filters are 52mm and the 55-300 is 58mm thread, so I had to hand-hold the filters in front of it, which is not entirely convincing, and the 55-300 doesn't have the best auto-focus ever. With this set-up I'd have to agree, you can get away with the linear polarizer; single-point AF appeared to work (with the usual degree of hunting, i.e. a lot), the 3-stop exposure difference was pretty much consistent across both filters and the images appeared usable on the rear screen, which is about as much comparison as the set-up deserved.

So, given that it's probably quite hard to get a linear polarizer these days, we're all quite likely OK. Unless we use old filters or cameras, which quite a lot of people around here do; maybe one will be along soon with the counter-argument...

Cheers

Jonathan

03-18-2018, 02:48 PM   #17
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QuoteOriginally posted by amoringello Quote
There is no reason to not use linear polarizers.
For a little bit of clarity

Quite simply: linear polarizing filters (FP) eliminate some of the reflections that, for various physical reasons, are polarized differently to the axis of the filter itself.
The maximum attenuation is for those reflections that have an orthogonal polarization with respect to the filter axis.
The effect is perceived by turning the filter until you see the reflections disappear (... or a part of the reflections). The filter then lets the polarized light through and blocks other components.

The circular polarizing filter (CFP) works the same way, but in addition to the polarizing filter, there is another layer, which is a lambda filter, with the function of making the polarization circular.
The reason is that many autofocus systems are deceived by linearly polarized light, so this "trick" is devised to be able to use the polarizer filter even on cameras equipped with autofocus.

Unfortunately, the results of a CFP are generally lower than those of an FP, but it is necessary to use it for cameras with autofocus.
You should also consider the effect on digital cameras that is usually, less than what can be achieved with film...

Returning to the question, the obvious answer is: it is better to use a circular polarizing filter. The brand is not a vital but subjective issue, ex the B+W has a slightly warmer pitch than the Haida or Kenko, Hoya etc.
03-19-2018, 09:25 PM   #18
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QuoteOriginally posted by Dewman Quote
I've got several CPL filters of different brands. Without a doubt, the Hoya brand is heads and shoulders above all the rest. At least that was the results of my "unscientific" test that basically consisted of looking through them and slowly turning them. Some didn't seem to make a whit of difference in reducing the glare, but Hoya? WOW! What a difference! My 72mm Hoya CPL was astounding at how much glare it reduced!


Maybe that's why they cost considerably more, eh? Second best was a Kodak CPL. The others? Meh.
I've had some good and bad polarizers, some that notably degraded the image when using my zoom at longer focal lengths, but I couldn't tell the difference between any of them by looking through them. They all reduced reflections similarly. I can't even tell the difference between regular and high-transmission polarizers by just looking, I have to measure with a meter. I can sometimes see a difference in color if I place polarizers side-by-side on a white surface but that's about it.
04-01-2018, 09:28 AM   #19
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Most brands offer severals product lines with different grades of quality (glass, coating) and features.
Hoya UV filters - PentaxForums.com
UV Filters, does coating matter? - PentaxForums.com
Best brand of filters? - PentaxForums.com

04-01-2018, 10:03 AM   #20
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With filters you really get what you pay for. I have a 67mm CPL that I've tried with my Tamron 17-50mm f/2.8 and it adds a colour cast and lowers contrast considerably. In contrast my little Marumi 49mm CPL that I can use with my DA limiteds is wonderful - no perceivable loss of sharpness and excellent contrast with no colour cast. I should use it more.

I'm sure that, as with lenses, there's some small variance from copy to copy, but I think it would be minimal. From my limited experience I'd recommend Marumi for excellent quality at a reasonable price.
04-07-2018, 08:22 AM - 1 Like   #21
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QuoteOriginally posted by h4yn0nnym0u5e Quote
...and yet you go on to say...

I just tried it, with a K1, a 55-300 and a linear Hoya and no-name CPL. The filters are 52mm and the 55-300 is 58mm thread, so I had to hand-hold the filters in front of it, which is not entirely convincing, and the 55-300 doesn't have the best auto-focus ever. With this set-up I'd have to agree, you can get away with the linear polarizer; single-point AF appeared to work (with the usual degree of hunting, i.e. a lot), the 3-stop exposure difference was pretty much consistent across both filters and the images appeared usable on the rear screen, which is about as much comparison as the set-up deserved.

So, given that it's probably quite hard to get a linear polarizer these days, we're all quite likely OK. Unless we use old filters or cameras, which quite a lot of people around here do; maybe one will be along soon with the counter-argument...

Cheers

Jonathan
OK, I'll bite, being old. On page 71 of the 645N Operating Manual, a paragraph on polarizing filters concludes with: "Use a CIRCULAR POLARIZING FILTER for proper autofocus operation."
04-07-2018, 09:45 AM   #22
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QuoteOriginally posted by kaseki Quote
OK, I'll bite, being old. On page 71 of the 645N Operating Manual, a paragraph on polarizing filters concludes with: "Use a CIRCULAR POLARIZING FILTER for proper autofocus operation."
Means: Don't use an linear PL (LPL) in combination with AF

04-07-2018, 11:57 AM   #23
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For those continuing to spread information about needing to use CP, have you actually tried it?
Before simply relying on a manual that is a re-write of a re-write... of manuals dating back 40 years or more, maybe do some critical thinking and try for yourself rather than replaying decades-old dogma that does not apply in real life.

I and others have tried this and have not experienced any issues.
I have yet to hear of any first hand issues... but it would certainly be interesting to hear of them and under what circumstances it has some effect.
04-07-2018, 12:24 PM   #24
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QuoteOriginally posted by amoringello Quote
For those continuing to spread information about needing to use CP, have you actually tried it?
Before simply relying on a manual that is a re-write of a re-write... of manuals dating back 40 years or more, maybe do some critical thinking and try for yourself rather than replaying decades-old dogma that does not apply in real life.

I and others have tried this and have not experienced any issues.
I have yet to hear of any first hand issues... but it would certainly be interesting to hear of them and under what circumstances it has some effect.

Serious question. So to the most part no issues to image quality? No odd artifacts? Etc?

Just wondering ive always heard only use circular with digital sensors, i mean if there is no problem as far as image quality goes, id prefer to use the linear type.


04-07-2018, 12:29 PM   #25
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Made in Japan Hoya filters are usually pretty good, but any of the brands
made in Germany are better quality, B + W, Rodenstock, Schneider etc.

Chris
04-07-2018, 12:53 PM   #26
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QuoteOriginally posted by Fcsnt54 Quote
Serious question. So to the most part no issues to image quality? No odd artifacts? Etc?

Just wondering ive always heard only use circular with digital sensors, i mean if there is no problem as far as image quality goes, id prefer to use the linear type.
Nothing with regard to focus nor metering that I've ever seen.
I've asked for stories from those with empirical evidence of such things and haven't heard of any with relatively recent cameras.
I remember hearing from a few persons who had seen issues back around 2005-ish but those same people also stated they do not notice the same issues with newer cameras. So, there may be some truth behind the statements, but it seems it is just another case of old beliefs being propagated as modern truth.
04-07-2018, 01:03 PM   #27
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QuoteOriginally posted by amoringello Quote
Nothing with regard to focus nor metering that I've ever seen.

I've asked for stories from those with empirical evidence of such things and haven't heard of any with relatively recent cameras.

I remember hearing from a few persons who had seen issues back around 2005-ish but those same people also stated they do not notice the same issues with newer cameras. So, there may be some truth behind the statements, but it seems it is just another case of old beliefs being propagated as modern truth.


Thank you, that helps a lot


04-07-2018, 01:37 PM   #28
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QuoteOriginally posted by ChrisPlatt Quote
Made in Japan Hoya filters are usually pretty good, but any of the brands
made in Germany are better quality, B + W, Rodenstock, Schneider etc.
Model line of an filter brand has more influence about the quality than the brand.
I'd already wrote that:
QuoteOriginally posted by angerdan Quote
Most brands offer severals product lines with different grades of quality (glass, coating) and features.

QuoteOriginally posted by amoringello Quote
For those continuing to spread information about needing to use CP, have you actually tried it?
Before simply relying on a manual that is a re-write of a re-write... of manuals dating back 40 years or more, maybe do some critical thinking and try for yourself rather than replaying decades-old dogma that does not apply in real life.
I and others have tried this and have not experienced any issues.
I have yet to hear of any first hand issues... but it would certainly be interesting to hear of them and under what circumstances it has some effect.
Basics don't have to be tried by everyone. They're already proven and accepted.
40 years ago there hasn't been AF SLR cameras. Technical and optical engineers who are involved in the manual writing process have experience and professional knowledge.
autofocus - Why do AF systems have polarizing elements? - Photography Stack Exchange

Not experiencing issues by siimply trying something don't change the basics. It even doesn't show them.
And i don't have any reason to buy an linear PL and trying to proove you right and the basics wrong.
All about Polarizers - Linear and Circular


QuoteOriginally posted by Fcsnt54 Quote
Thank you, that helps a lot
It's what you like to hear, but the information isn't correct.
04-07-2018, 02:56 PM   #29
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QuoteOriginally posted by angerdan Quote
Model line of an filter brand has more influence about the quality than the brand.
I'd already wrote that:


Basics don't have to be tried by everyone. They're already proven and accepted.
40 years ago there hasn't been AF SLR cameras. Technical and optical engineers who are involved in the manual writing process have experience and professional knowledge.
autofocus - Why do AF systems have polarizing elements? - Photography Stack Exchange

Not experiencing issues by siimply trying something don't change the basics. It even doesn't show them.
And i don't have any reason to buy an linear PL and trying to proove you right and the basics wrong.
All about Polarizers - Linear and Circular

It's what you like to hear, but the information isn't correct.

Things change. Don't get stuck living in the past and repeating old information that no longer applies.
Lots of people repeat old wives-tales simply because they never thought to question what they've been told.
Sad but true.

"Not experiencing issues by siimply trying something don't change the basics."
If first hand experience didn't "change the basics" the issue would still be present and this conversation would not be happening. Scientific studies are proven "wrong" all the time as more information becomes available, or as current technology changes.


The Wiki link is interesting and full of non-attributed information and lacking references. It is also full of questions without answers.
The last bit of text is also of most interest;
"However, I actually have never seen an ill effect from mounting a linear; maybe it’s all not data, just lore."


The other link has this to say;
"If you have a modern AF SLR the answer is almost certainly "yes"."
Still thought of as not definitive,100% certainty. It is quite possible there is no effect, as many will attest to.
The page is also heavy on description of film and slide. So maybe out of date??

The best description on this page about when things are a problem is as follows;
"There can also be small autofocus errors in some cases if any of the lenses in the AF system are birefringent (polarization sensitive), which can happen if plastic lenses are used and they are under some stress. If you care about your pictures and your camera needs one, spend the few extra dollars and get a circular polarizer."

I'm hoping Pentax doesn't use plastic lenses. I can't say for sure, but I suspect most of their nigher end cameras have probably used non-plastic parts for some time.


Sorry, but until you can borrow a LP (no need to buy something you won't use, jeesh) and give us your first hand results, I really don't put a lot of faith in your opinions, over first hand experiences.

Last edited by amoringello; 04-07-2018 at 03:04 PM.
04-07-2018, 06:07 PM   #30
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QuoteOriginally posted by angerdan Quote
Model line of an filter brand has more influence about the quality than the brand.
I'd already wrote that:




Basics don't have to be tried by everyone. They're already proven and accepted.
40 years ago there hasn't been AF SLR cameras. Technical and optical engineers who are involved in the manual writing process have experience and professional knowledge.
autofocus - Why do AF systems have polarizing elements? - Photography Stack Exchange

Not experiencing issues by siimply trying something don't change the basics. It even doesn't show them.
And i don't have any reason to buy an linear PL and trying to proove you right and the basics wrong.
All about Polarizers - Linear and Circular



It's what you like to hear, but the information isn't correct.


That article helps a ton. what i got from it is, if you are on a tripod in full manual mode, no autofocus, it really doesnt matter... image quality is going to be the same, but with one less piece of glass in front of the lens. Also you save some money as well.


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