My circular polarizing filter doesn't seem to have a very wide change spectrum?

[iris]

Do circular polarizing filters come in various strenghts or ranges of change?  ARe all C-polarizing filters the same?  Yes, I know how to use them. I know the 90degree angle to the sun and all that ...I feel that I should be able to rotate the filter and see through the lens excactly what the change will be...frankly I find it very difficult to see the amount of change in the blue of the sky using the filter that I have....shouldn't you be able to rotate the filter and observe the change gradations?  Shouldn't they be obvious as in a ND filter?  Should I ask for a "stronger" polarizing filter?

[Skirball · Accepted solution]

Polarizers can have different strengths.  Technically they should all be similar, since theoretcially they should eliminate all waves perpendicular to the axis.  But that's theoretical, and cheap polarizers might not be efficient.  What brand?

It's unlikely it's a complete fake, but I wouldn't be totally surprised if you bought a cheapo somewhere.  I've seen plenty of polarized sunglasses that aren't.

One thing: technically it's not 90 degrees to the sun, it's 90 degrees to a reflected surface.  The reflection has become polarized, which allows the polarizer to block it.  The effect on blue sky can vary, depending on how much reflection (haze) there is in the sky.  The best way to check that it's working is to look at sunlight reflecting off of something, like a shiny object.

[ebiggs1 · Accepted solution]

Polarizing filters do increase color saturation.  You should be able to see it in your view finder and LCD display.

A good way to visualize how this works is to aim your pointer finger at the sun while holding your thumb straight up. Everywhere your thumb points when you rotate your hand (while still pointing it at the sun) is where the polarizer will have the strongest effect. They require the camera to be pointed at a right angle to the sun for maximal effect.

The problem is all color saturation is not equal.  It can vary and not be uniform across the frame.  Another is when used on a wide angle or UWA lens the effect can be less.  Which can make it quite difficult to see the effect in a viewfinder or LCD screen.  Cheap ones can degrade IQ.

If I missed anything maybe Tim can help me out.  This is right up his alley. 

[ebiggs1 · Accepted solution]

It is easy.  Basic set up. Take three or more exposures.  One under, one correct and one over exposed.  You need a post editor.  I like and use Photomatrix Pro.  It automaticly stacks the exposures and applies the correct settings.  Plus it has other features for further adjustments.

There is a free trial version.  BTW, Photoshop can do it, too.

[iris]

Remarkable results with your HDR....I am interested in HDR but have no real understanding of it.  I get the impression you dont need a lot of lenses?  ? what? I saw friends on a recent trip to the mountains raving about the little bit of weight they took with their cameras...I'm not sure I understand HDR at all right now?

[ebiggs1 · Accepted solution]

It is easy.  Basic set up. Take three or more exposures.  One under, one correct and one over exposed.  You need a post editor.  I like and use Photomatrix Pro.  It automaticly stacks the exposures and applies the correct settings.  Plus it has other features for further adjustments.

There is a free trial version.  BTW, Photoshop can do it, too.

[ebiggs1]

Here is a "Old Red Barn" they are restoring close to me.

Give it a try, sometime.  

[Skirball · Accepted solution]

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@iris wrote:

Remarkable results with your HDR....I am interested in HDR but have no real understanding of it.  I get the impression you dont need a lot of lenses?  ? what? I saw friends on a recent trip to the mountains raving about the little bit of weight they took with their cameras...I'm not sure I understand HDR at all right now?

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You need a tripod, not a lens.  Well, obviously a lens, but a tripod is the standout requirement for HDR.  Basically all you're doing is taking photos as multiple exposures (very dark, dark, normal, light, very light) and combining them into one image with a large (or "High") dynamic range (the 'distance' between the darkest and lightest points in an image); hence the name HDR.  You can shoot it without a tripod, most software can try to align the frames, but it's much better to just use a tripod if available.

As mentioned above, Photomatix is the name brand in HDR, but that's changing and the technique evolves.   It's far superior to control in Photoshop, however.   There's a plug in for Lightroom called Enfuse (free) that is very powerful, but not as user friendly.  And the soon to be released Lightroom 6 will have HDR built in; we're all eager to see what that looks like.

The examples that eBiggs posts really show tone mapping more than HDR.  All HDR (and non-HDR) images have to be tone mapped to display on a LED screen, but if you search for "tone mapped" you'll see that there is a look associated with the term. 

On the flip side, HDR images can be tone mapped to look normal, mearly trying to squeeze a large dynamic range into one picture. A very common use is in Real Estate/Architectural photography when dealing with lots of windows.  The difference in light levels between the inside lights and outside can often be far too large for a camera (even though your eyes can adjust ok).  So you're left with either completely white windows, or dark interior.  The goal isn't to make something that looks 'tone mapped', but to have it look normal.  Like this:

Even with lighting I couldn't completely balance out the sun, so I simply stack a few images to fill in the low spots.  It doesn't look like anything special, but it's not supposed to.  You can see the outside has a slight bluish tint to it.  Poor tone mapping on my part. 

Another example, where the left and back walls were windows, creating a bright gradient out of the lower left, leaving the back completely dark. 

Again, you're not suppose to look at it and think HDR, it's suppose to look like an ordinary photo.  Just some examples of another side of HDR...

[ebiggs1]

iris,

A tripod is certainly the best way to do HDR but not a requirement by any means.  Both of the shots I posted are hand held.  You do need at least three exposures and five is better.

HDR has great ability for adjustment.  The two old barns have a certain amount of things dome to make them look like they do.

I printed them on pearl metalic paper for that certain look, too.  They are stunning in real life and they sell very well.

It is possibile to do HDR that has a normal look or at least as normal as HDR can be.  Since the range is vastly extended.

Photomatrix Pro, my choice software, is a plug-in for Lightroom.  So you can start in LR do your stuff. Click the plug-in go to Phtomatirx and let it do its stuff and bamm you are back in LR.

This isn't new. The term HDR maybe new but PS could always do this.  And I used to do it in the darkroom with film.  We just didn't call it HDR.

There is even video HDR but I am a stills guy.

[iris]

Thank you for reminding me  of several things in your response...yes, the lens does seem to cut water reflection and such but I still am aggravated at not being able to determine the amount of change in my view finder or on the LCD on the back of my camera...A great boon to photography would be to fix that LCD display so that you can tell "doodleysquat" when the sun is bright outside.

[wm700293]

IMHO the easiest way to check a "polarizer" is to hold it in front of an LCD (computer or TV) screen and rotate it while looking through it *(with an image displayed on the screen). The view through the "polarizer" should "go black" at some point in the rotation:

                     1.) IF screen is LCD

                     2.) AND polaroid filter is functional

                     3.) THEN screen as viewed through rotated filter will darken

                     4.) ELSE screen is not LCD

                     5.) OR polaroid filter is not working

Note: There are different types of screens, LCD and NOT LCD. (LCD=Liquid Crystal Display)

          Typically Sony TV screens are LCD, while Panasonics are not (different technology)

Give it a try...

WDM

[TCampbell]

It helps to understand what a polarizing filter actually does.  

Light travels as a wave.  The wave has an orientation.  As light leaves its source (e.g. the Sun for example) the orientation of the wavelengths is random.   But when light boucnes off any surface, it will take on an orientation based on the angle of surface that reflected it.  The shinier or more reflective the surface... the stronger the effect. 

If light is originating from a direction which is EITHER roughly directly ahead of you OR directly behind you, then the orientation of the waves will still be random and the polarizer will seem to have little to no effect.  

If the light is originating from a direction which is orthogonal to you (come from the sides or above) then the light will be strongly polarized to a specific orientation as it reflects.

The polarizing filter has parallel lines which you can think of as a series of "slits".  If the orientation of the wave matches the direction of the slit then the light passes through.  If the orientation of the wave is orthognal to the orientation of the slit then the wave of light is absorbed.

When you use a polarizer on a cloudy day, the clouds will diffuse the light (light a giant "soft box") and the light will seemingly originate from all around you.  The polarity of the light waves will be random because the surfaces that reflected those waves were also random.  It will seem to have little effect.  

On a sunny day, the polarizer will have a very strong effect.  Foliage looks greener because part of what you see without a polarizer is the natural color of the leaves, but the leaves also have a reflective coating -- so part of what you see is light reflecting off a shiny surface and not the true color of the leave.  When you add the polarizer (and tune it) then you block the reflections but allow the natural color of the leaf to come thorugh.  It isn't so much that the polarizer saturates colors... it's that it blocks reflections so that you can see what was hiding behind the mirror surface.  If there was no mirror-like reflection then you wont see any color saturation as you tune the filter (you are already seeing the natural color of the objects.)

The sky looks bluer because of tiny impurities in the air (which can even be humidity) and these are reflecting light.  The intensity of the polarizer will changed base on the "transparency" of the air and the nature of the impurities in the air.

Lastly... when you use a polarizer on a lens at a very wide focal length, the amount of light blocked will change based on the angle of the light.  This creates a dark-ish band in the area where the polarizer is blocking most of the reflections and will weaken as you get farther from that sweet-spot.  The result is an image that appears to have a dark-band going through it.  Polarizers look best when used on normal to long focal lengths.

[Mitsubishiman]

For what it's worth I have several Hoya CP's basically one for each lens, in my experience even when I am even 90 degrees to the light plain I have experienced less than I thought for effect, what I discovered is, my eyes are the problem lol, between that and the reflection on the LCD it only appeared that what I saw was less effect, when I looked through the viewfinder I then saw what I was looking for, just thought I would mention it.

[RobertTheFat]

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@Mitsubishiman wrote:

For what it's worth I have several Hoya CP's basically one for each lens, in my experience even when I am even 90 degrees to the light plain I have experienced less than I thought for effect, what I discovered is, my eyes are the problem lol, between that and the reflection on the LCD it only appeared that what I saw was less effect, when I looked through the viewfinder I then saw what I was looking for, just thought I would mention it.

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The only culprit I can think of is light reflecting off of your glasses. If it doesn't make it through to your eyes, it won't matter what its polarization is.