02-25-2015 10:18 AM
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?
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02-25-2015 11:51 AM - edited 02-25-2015 11:51 AM
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.
02-26-2015 11:23 AM
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.
02-26-2015 11:17 PM
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.
03-05-2015 10:32 AM - edited 03-05-2015 10:33 AM
@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:
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...
02-25-2015 11:51 AM - edited 02-25-2015 11:51 AM
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.
02-25-2015 12:52 PM
The polarizer that I have is a Hoya 77mm that I use on my 17-55mm f2.8 lens. Now I will say that the colors generally in the photos I have processed using this filter are richer, but my issue is with gray, overcast skies. In those situations where there is a patch of very faded blue showing through the clouds I never seem to be able to determine as I look through the lens and turn it how much I am affecting the "blueness of those patches". I thought you were supposed to be able to see those changes as you rotate the lens...but I have not found much success noting those changes using the LD display or through the lens...
03-21-2020 04:10 AM
02-25-2015 12:56 PM
02-25-2015 03:35 PM
02-26-2015 11:23 AM
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.
02-26-2015 06:01 PM
02-26-2015 07:01 PM
e-biggs, I notice you have a Sigma lens..my husband recently purchased Sigma 150-500mm f5-6.3 lens for my Canon..due to my unhappiness with my Hoya and apparently a rarity of polarizers for the 86mm lens in question, what do you use in the way of a cpl for your Sigma and what 86mm cpl would you suggest for my Sigma named above?
02-26-2015 10:51 PM
iris,
I have that very Siggy. It is a great lens for the money and will give all but the many thousand dollar rigs a run.
I use a B+W polarizing filter but I use it on more normal lenses. One problem with the big Siggy and its ilk, is they are slow. It really can't afford any f-stop penality. And filters of any kind degrade IQ.
Now what do I do about it? Photoshop of course. In reality, the only filter that you can't duplicate in PS is the ploarizer.. But you can agive it a darn good try.
BTW, have you done any HDR? I have beeb toying around with it a little bit. Some pretty "interesting" results!
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