Help with circular polarising filter

[DickyOZ]

I have no idea which camera settings to use to get the best out of this filter (Hoya HD CIR-PL Made in Japan). I have attached a couple of pics SOOC for C&C. E-M1 and 12-40mm PRO lens. The weather was 29C with extreme UV. With the lens hood on it is hard to rotate the filter (its also not really apparent what has changed when I do). I think I need to learn some basics before I get the desired results. I used spot to avoid blowing the highlights on the birds/boat.




Dicky.

[russellsnr]

Hi, You must have the sun at 90 deg to the lens ie from your left or right shoulder, a lens hood should not be required as you would or should not get any flare with the sun at your side, don't always feel you have to use the pol at it's full strength, with wide angle lenses be aware that if you shoot as in your case 12mm you may get an uneven sky at the sides of the image. there are many tutorials on-line on how to use this filter.
https://www.youtube.com/watch?v=0qxrL9SdywM

Russ

[Dave Humphries]

Polarisers are a complex topic - they can have many different effects on a scene - the problem is that much of the guidance vastly over simplifies; for example, that YouTube Russell links starts by saying "you have to use it 90 degrees to the sun, not when it is behind you", which is only true for some aspects of how you might be wanting to use a polariser. (it does later mention some other aspects of their use, but doesn't give any example shots, nor mention that the rule about 'sun not behind you' doesn't apply to these - and that's how so much mis-information occurs about these.

There are also other factors; e.g. lens angle of view, what's in the scene, which way you're facing (relative to the sun), cloud cover, (etc.) that will impact apparent effectiveness.

So the question is, in the scene above, what did you want to achieve Dicky?
e.g.
Render the water clearer, so you can see through it to the bottom?
Darken the blue of the sky?

The angle of rotation for the best of one will not simultaneously give the best for the other, so an informed choice has to be made.

Camera settings per se, won't affect the results it gives you (beyond not over exposing when compensating for the light loss of 1.5 to 2 stops), although that compensation might be via ISO, shutter speed or aperture and those may adversely impact the captured scene if you don't choose which one(s) to adjust wisely.

There's also a skill to rotating; knowing what to look for, where (in scene) and the fact that only half a rotation will give you the full range of effect (arguably 90 degrees worth for skies), so over zealous rotation will mask the subtle effects and may confuse some.

I'm in a rush now, perhaps more later if others haven't said all the detail I could, had I more time.

Cheers, Dave

[IzzieK]

'Tried to send you a video that explains how the CP and ND work but I do not know how to upload a video that comes from my own file to here...I tried to find it on YouTube but it isn't there. Sorry...but Dave's explanation is more closer to what I have...

[Dave Humphries]

This guy's (sub 3 minute) video is pretty thorough and fairly accurate (even if he is a bit stilted, in, reading, his, script) with several helpful demonstrations on various subjects. A 9/10 from me.



Link to Christopher Frost's Photo101: Polarizing filters, why they're so neat...and how to use them video on YouTube.

Cheers, Dave

[Shadowman]

There's an old saying about looking at the world through rose colored glasses and I read somewhere that looking through polarized sunglasses will give you a good indicator of what will look good photographed through a cpl. I've seen the difference and would often shoot a scene even though I didn't have a cpl on my lens and I would edit the heck out of the image trying to recapture the look I saw through my sunglasses. The advise given on the use of a cpl will give you the results you are looking for, sizing up the scene will be all up to you.

[Mike Buckley]

You must have the sun at 90 deg to the lens ie from your left or right shoulder

Dave mentioned that the above statement is not true, at least that it's not true when no context is provided. That myth is perpetuated on the Internet so much that it is worth confirming that Dave is correct that it is only a myth.

I reviewed only the first video provided by Dave. All of the information in that video is true except the three statements explained below:

"If you're shooting a sky, the effect will really work only 90 degrees from the direction of the sun." That's not true. It would be correct to say about the sky that the greatest effect will occur when shooting at 90 degrees from the direction of the sun and when the sun is at its lowest point. The effect will be less and less the more the sun is higher in the sky and/or the more you are shooting less than 90 degrees from the direction of the sun. If you shoot with the sky directly in front of or behind you, there will be no effect on the sky.

"Don't forget to take the polarizer off when you're shooting indoors or when it gets dark outside." His own video displays two situations (photographing the book spines and the television) when using a polarizer indoors can be very helpful. There are many other situations when using a polarizer indoors can be helpful, so always try it and decide whether the benefits are worth losing the amount of light entering the camera.

As for shooting outdoors when it gets dark, remember that the scene is lit by sunlight reflected off the moon. The scene can also be lit by man-made light. So, a polarizer will have some noticeable effect in many situations when shooting outside in the relative dark.

"The filter blocks off about 50% to 75% of your light." It's more accurate and helpful to understand that most polarizers reduce the amount of light entering the camera by about 1 1/2 to 2 stops. That depends on the filter and its position. I recently read about a newly released filter whose primary competitive advantage is that it blocks far less light.

I will add that there is a common perception that when shooting outside with a cloud-covered sky there will be no effect when using a polarizer. It is true that there will be less effect but it is not true that there will be no effect. I recently demonstrated this to my wife. Not only was the sky cloud-covered but we were in the bottom of a gorge where no direct sunlight was in the scene; the scene was lit only by reflected light and light diffused by the clouds. Yet using the polarizer still eliminated some of the unwanted glare that otherwise would have appeared in the photo.

[DickyOZ]

[B]
So the question is, in the scene above, what did you want to achieve Dicky?
e.g.
Render the water clearer, so you can see through it to the bottom?
Darken the blue of the sky?
Cheers, Dave

Hi Dave,

Many thanks for the advice.
I was hoping to do both, but now realise that is going to be tricky. I definitely need to put a marker on the filter's rotating ring, I''ll align it with the infinity marker on the lens to give a datum.

I don't mind losing a couple of stops, there is usually more than enough light when I use this filter.

My other main issue is loss of sharpness and detail when using the filter, I'll have to do some controlled test shots to see what is going wrong.

Dicky.

[DickyOZ]

There's an old saying about looking at the world through rose colored glasses and I read somewhere that looking through polarized sunglasses will give you a good indicator of what will look good photographed through a cpl. I've seen the difference and would often shoot a scene even though I didn't have a cpl on my lens and I would edit the heck out of the image trying to recapture the look I saw through my sunglasses. The advise given on the use of a cpl will give you the results you are looking for, sizing up the scene will be all up to you.

Thanks John,

It was looking through my Polaroid sunnies that made me decide to get the filter. So far I haven't got even close to capturing what I see through my sunnies.

Dicky.

[DickyOZ]

This guy's (sub 3 minute) video is pretty thorough and fairly accurate (even if he is a bit stilted, in, reading, his, script) with several helpful demonstrations on various subjects. A 9/10 from me.



Link to Christopher Frost's Photo101: Polarizing filters, why they're so neat...and how to use them video on YouTube.

Cheers, Dave

Very handy video, I only gave him 8/10 because his filter was really dusty.

[CP140]

I have no idea which camera settings to use to get the best out of this filter (Hoya HD CIR-PL Made in Japan). I have attached a couple of pics SOOC for C&C. E-M1 and 12-40mm PRO lens. The weather was 29C with extreme UV. With the lens hood on it is hard to rotate the filter (its also not really apparent what has changed when I do). I think I need to learn some basics before I get the desired results. I used spot to avoid blowing the highlights on the birds/boat.

Dicky.

I too have some trouble using a CPL to it's best/full capability. Half the time I forget it's on the lens and only realize it was there when I review my shots later and notice that something doesn't look quite right.

The one advantage I have is that a number of my lens hoods have a little slide-out "window" on the bottom that let me stick a finger tip in and rotate the CPL... if I remember it's on the lens!

[DickyOZ]

OK, I've got the basics now.
Sun behind (does indeed have less effect):
filter @ 0°

filter @ 90°


Sun at 90° (Does have most effect and also uneven)
filter @ 0°

filter @ 90°

Somewhere in between would have given the desired result on the sky.

Reflections:
filter @ 0°

filter @ 90°


Rose:
filter @ 0°

filter @ 90°

No filter me trying to be creative:


It is also quite obvious that the EV needs a lot of adjustment when using the filter; my normal -1/3 needs to go to +1 at least for many shots.

Dicky.

[Mike Buckley]

It is also quite obvious that the EV needs a lot of adjustment when using the filter; my normal -1/3 needs to go to +1 at least for many shots.

When shooting the exact same scene lit exactly the same and when metering and using other camera settings exactly the same, you will NOT need to change your EV adjustment when using a polarizer or not. Though the polarizer allows less light into the camera, your camera meter "notices" that and automatically adjusts accordingly. The same is true when using any kind of filter in front of the lens that reduces the amount of light entering the camera body. This can easily be verified by placing your camera on a tripod, by using the exact same lighting in a controlled indoor environment not subject to changes in outdoor light entering the scene, and when using the exact same camera settings.

[Dave Humphries]

When shooting the exact same scene lit exactly the same and when metering and using other camera settings exactly the same, you will NOT need to change your EV adjustment when using a polarizer or not.

Sorry Mike, but I don't think that's always going to be the case ...

I think we may need to adjust EC (Exposure Compensation) when using a CPL in some circumstances:

Granted the meter compensates for the 1.5 to 2 stops difference, but, if the use of the polariser has removed a 'bright cloud' sky reflection from say; the surface of water, revealing a dark mud below, this must affect the ratio of light and dark areas in the scene, which the metering will respond to, so if we don't compensate, we risk other areas, such as the white painted jetty, becoming a different exposure (possibly even blown).

It isn't a huge problem in Dicky's shot above because the sky was blue, but had it been white cloud, I think we'd see a difference.

Dave

[Mike Buckley]

Dave,

Nothing is always going to be exactly the same. However, my response to Dicky was in the context that he thought the use of a polarizer was requiring him to adjust his EV by about 1.33 stops "for many shots," so much so that he thought the need for the change was "quite obvious." It is going to be a very, very rare situation that such a large change in EV is going to be required simply because a polarizer is being used.

[William W]

. . .The weather was 29C with extreme UV. . .

and

OK, I've got the basics now. . .
filter @ 0°

filter @ 90°

Somewhere in between would have given the desired result on the sky.

If the ‘desired result on the sky’ was to attain an even deep/rich sky across the image then, setting the CPL ‘somewhere in between’ would probably NOT have given that result.

The reason is the lens used was set at FL = 17mm and for that particular lighting scenario.

The two images seem to be made using one after the other and from the same view point and they have the same FoV - the fact that the CPL created a disparity in the depth/richness of the blue sky across that Field of View then ANY setting of the CPL to affect the depth of blue in the sky, would affect the sky - unevenly.

Please refer to our previous conversation here, Post #12, extract below - (my bold now for emphasis):

"Olympus Micro Four Thirds System?"

"Be careful that you might not get what you expect to get – points to consider:

With Circular Polarizing Filters Blue Banding is fairly common in most sky images which compass a FoV equivalent to 35mm lens on 135 Format Camera (aka “Full Frame”). I have had Blue Banding in the sky when using a 70mm Lens on a 135 Format Camera – that means you’ll have to be very careful if you are wider than 18mm on your WA zoom and still be aware of large expanses of sky in the frame when using that lens at any Focal Length. This point warrants attention considering that your purpose is “details in the clouds”.”

. . .

“At the beach, for any Wide Angle Shot requiring cloud detail when there a lot of haze, I would first use a UV Series or Skylight Series Filter, rather than using a CPF for that task.”

*

In that previous conversation, the reason that I asked if was an Olympus Camera that was being used was because I was curious to know if it was a model which does NOT employ an OLPF (Optical Low Pass Filter) and the question at the end of Post #12 in that conversation was because some (many?) digital camera sensors which do not use an OLPF also have a ‘reduced’ IR/UV filtration on their sensors.

Evidenced by the EXIF of the image samples above, it is indeed an Olympus Camera (E-M1) which is being used and that particular camera does NOT employ an OLPF. I am not au fait with the Olympus 4/3 system to know if the IR/UV filtration used on that model varies all that much from the ‘typical’,.

But in any case, if the aim is to better render clarity of clouds, or to generally cut through UV haze to render subjects in the distance sharper, the advice to use a UV or Skylight Filter rather than a CPL Filter for shots in High Haze / High UV conditions still stands

This is especially so for shots which have a wide Field of View: re-iterating we would surely aim to avoid any Blue Banding across a wide expanse of sky.

The Blue Banding introduced by CPL Filters is difficult to adjust/correct in Post Production - whereas in Post Production the sky is relatively easy to make richer and darker.

On the other hand, obviously if the aim is to make the water clear and free from glare so that the image reveals what is below the water, then a CPL does that


WW

[Dave Humphries]

Dave,

Nothing is always going to be exactly the same. However, my response to Dicky was in the context that he thought the use of a polarizer was requiring him to adjust his EV by about 1.33 stops "for many shots," so much so that he thought the need for the change was "quite obvious." It is going to be a very, very rare situation that such a large change in EV is going to be required simply because a polarizer is being used.

I agree, but your statement was the absolute one; "you will NOT need to change your EV adjustment when using a polarizer or not."

However, I have now looked at the EXIF in all Dicky's example pictures and the EC is -0.3 in all of them!
I believe he was in Manual Exposure mode, so this may not be relevant anyway, depends whether EC on Olympus biasses the meter (as Nikon does) or not (as Canon do).

Taking the jetty reflection example; the exposures were 1/80s, f/7.1 ISO200 against 1/100s, f/8, ISO200, that's 2/3 stop difference for the 90 degree rotation and change of reflection. Note we're now discussing only rotation of polariser, not whether it was on or off the lens.

So I'm not sure where his comment about changing "EV" from -0.3 to +1 originates, may be that was regarding adding the filter (or not) and he meant EV (an absolute light level, relevant in Manual mode), not EC.

I have no idea whether any PP adjustment of exposure was done, or whether the shots were taken at same meter reading, etc. - there are too many vagaries and unknowns to draw solid conclusions really.

Cheers, Dave

[Mike Buckley]

I agree, but your statement was the absolute one; "you will NOT need to change your EV adjustment when using a polarizer or not."

Now that I have read my post again with fresh eyes on a new day, I see what you mean. Good for you for pointing that out!

[dem]

About half a dozen of polarizers I have tested, all cut off between 1.25 and 1.7 stops of unpolarized light. But this number will be different in the field, as most scenes with reflections and shiney objects will have a small percentage of polarized light.

By rotating the polarizer you are varying the total amount of light reaching the sensor. Say 1.5 stops light loss at 0 degrees (all polarized light is let through) and 2.0 stops light loss at 90 degrees (all polarized light is blocked). The part of the light which was not polarized, is reduced by the same amount at any orientation of the polarizer.

Now try photographing an LCD screen that emits polarized light. If the room is dark, the polarizer can easily cut off not 2 but more like 10 stops of light.

[rpcrowe]

I don't usually touch my exposure compensation settings when using a polarizer. That is not to say that my exposure doesn't change, it most certainly does. However the camera's meter usually compensates for the exposure difference.

Another thing, I don't always turn my polarizer for maximum effect because that often seems over done to me. I will most often use my polarizer at about 2/3 or 3/4 or maximum polarization...