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Tutorial: Circular Polarizer Filters

Brick Flicks & Comics Academy photography glare CPL polarizer filter beginner

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#1 Scouty

Scouty

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Posted 24 August 2012 - 09:59 PM

Working with LEGO has always been fun, but LEGO is shiny and more often than not, there is glare from a light source when we photograph them. There are several ways to remedy this. One option is to place the lamp in a different location so the light reflected is hidden from the lens of the camera. Another option I've heard of is to use pencil erasers to dull the shiny brick. The least invasive way to remove glare from your set is through a circular polarizer.

What is a Circular Polarizer?

A circular polarizer (CPL) is a filter that only allows a certain angle of light to pass through it. Here are two articles that go into depth of the physics behind a polarizer. To put it very simply, scattered light passes through the filter and either the vertical or horizontal band of light will pass through. The angle of which the source light hits your object is important, and usually a 45 degree angle to the object will get you the best results.

Most circular polarizers are also Neutral Density filters (filters that darken the shot without affecting color) and are usually graded to stop down an image by 2 stops. So if you have an f/stop of 4 on your lens, it will result in an f/stop of 8. You will need to add more light if it makes the scene too dark.

A CPL will not completely remove a glare, depending on the angle and strength of the light, but it will cut it down a lot.

This is the circular polarizer I used for this topic. I had a better one (which had a smoother rotating ring), but that got stolen :shrug_confused: . These things range from $6 to $200. The one I used is from the lower end. The price doesn't affect the effect, but you'd probably get a better quality, longer lasting product going for a medium to high range polarizer.

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A side view of the polarizer. Here you can see that this is a two piece filter, one that screws onto the lens and the other that can rotate freely, changing the angle of light that passes through.

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Here are some photos of the circular polarizer in use with LEGO pieces. The first picture is to demonstrate how much light is cut out from the neutral density aspect of the filter

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And now it's not over-exposed. The next two pictures will demonstrate how well the CPL removes glare from LEGO pieces

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As you can see in the above pictures, the glare on the eyes and nose, as well on the side of the black body, has been removed significantly. You can also see that the glare on the seams of the LEGO bricks and around the studs on the floor has also been removed.

Two more examples:

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In the previous examples, I showed you how the CPL worked with figures and objects. In this next example, I'm using the very shiny bricks in the background. Straight on, like in the previous pictures, provided little effect in removing the glare. Changing the angle of the set, with the source light directly in front produces a dramatic effect in removing the glare.

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I've recorded a video of the CPL in action so that you can see exactly is happening when the filter is rotated. Take note of the frog, the eye of the panda, the handlebars of the motorcycle (and the blue plastic of it, as well), and the minifigure's hair, head, and leg. The back wall and LEGO studs are also affected, but not as much as the other pieces. Like I noted in the above example, the reflections in the back wall are hardly removed by the CPL, which you can clearly see my hands rotating the CPL on the camera lens. Sorry for the shakiness.

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In conclusion, the CPL is not a necessary part of your photography set up, but it does help reduce unwanted glare/reflections on your set. Without the glare, the LEGO pieces are no longer washed out and have more contrast. Obviously, not every camera will have a CPL that will fit on it. There are other ways to attach a CPL to the camera and different types of CPL's (like a square plastic gel, like the polarized lenses of 3D glasses). Just holding it with your hand will work just as well,.

One last interesting tid-bit about the polarizer: If you put two CPLs in front of each other, it is possible to completely block out light.
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Also tagged with one or more of these keywords: Brick Flicks & Comics Academy, photography, glare, CPL, polarizer, filter, beginner

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