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

iris
Enthusiast

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?

4 ACCEPTED SOLUTIONS

Skirball
Authority

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.

View solution in original post

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. Smiley Happy

EB
EOS 1DX and 1D Mk IV and less lenses then before!

View solution in original post

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.

EB
EOS 1DX and 1D Mk IV and less lenses then before!

View solution in original post


@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?


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:

 

16268587496_a482740283_z.jpg

 

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. 

 

8467443718_e475fee384_z.jpg

 

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...

View solution in original post

37 REPLIES 37

No, you are not correct. It is because you need to use a circular polarizer instead of a linear polarizer. Linear polarizers interact with the phase detect auto focus. Circular polarizers don't affect focus, but they don't work as well either.


@kvbarkley wrote:

No, you are not correct. It is because you need to use a circular polarizer instead of a linear polarizer. Linear polarizers interact with the phase detect auto focus. Circular polarizers don't affect focus, but they don't work as well either.


When it comes to linear vs circular, I think one is just as bad as the other.  I think both wreak havoc with AF systems.

 

5AFD1DC0-3334-4DBC-A33E-E797151D3526.jpeg

--------------------------------------------------------
"The right mouse button is your friend."

" I think both wreak havoc with AF systems."

 

Perhaps not "havoc" but you are certainly correct.  The exposure issue can be as bad or even worse. Again, for the record all polarizers are linear, otherwise they would not work at all. They just have an additional layer or filter if you will included.

 

 

EB
EOS 1DX and 1D Mk IV and less lenses then before!

I will add with the possible exception of reflection from water or windows, etc, the ploarizer filter, as is all other filters, possible exception of the ND filter, are obsolete. Post editing and digital files have rendered them largely irrelevant.

EB
EOS 1DX and 1D Mk IV and less lenses then before!

Filters are not obsolete. Not even close.

 

First of all, when you capture an image that is filtered by a real glass filter you capture the image how you want with 100% of the detail possible by the sensor. 

 

If you rely solely on editing, you have to crush details to get the "look" you want. 

 

In reality, there is usually not a lot of detail in the highlights of an image, editing that is a huge pain. And if you do go through all that trouble the end result is a lower quality image.

 

There's also the issue of time. With a polarizer you can greatly reduce highlights and reveal color and detail without having to take the time to edit every single picture.

 

Also, when using filters I tend to get a more consistent look from shot to shot vs. relying on editing alone.

 

Plus it's kind of fun using filters.

 

Anyway, hope this helps!

 

 

"...when you capture an image that is filtered by a real glass filter you capture the image how you want with 100% of the detail possible by the sensor."..."If you rely solely on editing, you have to crush details to get the "look" you want."

 

Shoot Raw format, solves that issue. Second take a course in Photoshop.

 

"Plus it's kind of fun using filters."

 

Just as much or more so to watch your image develop from a good to great photo.  This is no different than our old darkroom abilities. But some folks did just drop their film off at the drug store and picked up the prints a week later?

 

I agree there are a few, very few, instances where certain filters can be useful but otherwise they are largely obsolete. I must have 25 or 30 filters of all kinds and types sitting on the formerly stop bath stained shelves of my old darkroom.  They have been sitting there for years and years!

EB
EOS 1DX and 1D Mk IV and less lenses then before!

What size? Any 77mm, 62mm, or 58mm? I'm always looking for cool filters. I'll pay.

" I must have 25 or 30 filters of all kinds and types sitting on the formerly stop bath stained shelves of my old darkroom. They have been sitting there for years and years!"

DSLR cameras have a mirror which is the cause of the problem. A linear polarizer can cross polarize, causing the image to darken or go completely black. Simular to an ND filter. Our old film SLRs used fully reflecting mirrors.  Meaning they had mirrors that reflect all polarized light with equal intensity to a point. DSLRs with autofocus use partial reflecting mirrors. The reduced reflected light, the key point here, goes to the viewfinder and metering systems.  And, some light goes on to the auto focus sensors.  This reduction can cause exposure errors and/or autofocus errors.

 

All circular polarizer filter are linear.  They just have an additional layer that "spins" the light, so to say. This fixes the exposure and focus errors or at least reduces them to a non-critical level. Will a plain linear polarizer work on a DSLR, yes, it will since the mirror is completely out of the way of the sensor when the photo is actually taken. However, you run the risk of the exposure or auto focus errors.

 

Perhaps a little simplistic but that is the basic idea.

EB
EOS 1DX and 1D Mk IV and less lenses then before!
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