General Questions - Should be easy to answer!

Hey!

I'm new to the game. I'll get straight to the point: I have three simple questions -

1) Whats the point of a lens hood? Why would you want to constrict light?
2) Why would one buy a polarizing filter?
3) A lot of great photos that I have seen have this slight but noticeable "shading" along the edges of the photo - like a vignette. Is this edited, or does this happen with the picture?

1: The lens hood does not constrict the light coming from the subject, the lens hood prevents light from off to the side, outside the area you are photographing, from causing glare on the front of the lens.

2: A polarizing lens has several things it can do, all of which are difficult or impossible to do in post processing. Light has polarity, "A and B" or "+ and -" or something like that, and the CPL will filter out one or the other polarity.

As an example, light coming from the sun is all the same polarity. When the light is reflected or refracted it changes polarity. So if you are looking at the surface of a still pond of water you can use the CPL to either enhance the reflection you see in the surface of the water or to reduce the reflection so you see more of what is under the surface. The CPL also increases contrast and can make blue skies look really, really blue.

3: Any of the above. Some lenses will do this especially at their widest focal length and widest aperture. Sometimes a lens hood can cause a little of this. Sometimes people add it for artistic effect.

Hi Logan - and welcome to POTN .

The lens hood does a couple of things. First, think of ballplayers out on the field on a bright sunny day, and how they crease the brim of their ballcaps to put their eyes in shadow. It stops the glare from interfering with their vision. This allows them to see the ball and plays more clearly.

Same thing with a lens hood - it prevents unwanted "side" or other bright light from scattering across the front element, resulting in flare and glare which will diminish the quality and apparent sharpness of the shot. It will also result in a richer, more colorful shot with an increase in pleasing contrast.

The hood is also an excellent physical barrier against bumps, knocks, curious little figures, and offers some protection against unexpected lens encounters with the floor or ground. - Stu

Oh - sorry, forgot about your other queries: The CPL can greatly enhance the photo when used under the right circumstances. Typically this is at a right angle to the sun, or at least some angle to it.

It will minimize glare, flare and unwanted reflection, darken a blue sky, make the clouds more prominent, and generally improve saturation and contrast to the overall image. Here is an example:

http://www.pbase.com/s​apearl/image/87234244

Ken (above) provided you with an excellent definition of vignetting, so I won't try to improve upon it.

Thanks to all of you! That really helped. Don't know if I need a lens hood right now, but a polarizer is definitely on my list.

Logan Graham wrote in post #8953970
Thanks to all of you! That really helped. Don't know if I need a lens hood right now, but a polarizer is definitely on my list.

One cool trick to see the polarizer at work is to look at an LCD TV or computer monitor through it. The light being emitted is all at the same polarity so if you turn the filter to the correct orientation the monitor will appear completely black as if turned off.

krb wrote in post #8953986
One cool trick to see the polarizer at work is to look at an LCD TV or computer monitor through it. The light being emitted is all at the same polarity so if you turn the filter to the correct orientation the monitor will appear completely black as if turned off.

My physics teacher gave us a bunch of filters on day, so we played around with them. That was fun.

krb wrote in post #8953986
One cool trick to see the polarizer at work is to look at an LCD TV or computer monitor through it. The light being emitted is all at the same polarity so if you turn the filter to the correct orientation the monitor will appear completely black as if turned off.

Happens when wearing sunglasses too...usually mobile phones appear not to work

Logan Graham wrote in post #8953970
Thanks to all of you! That really helped. Don't know if I need a lens hood right now, but a polarizer is definitely on my list.

I always buy hoods for my lenses immediately, if they don't come with one. And I put it on on the first day and never take it off. Some people mount clear or UV filters on their lenses to protect the front surface, but large numbers (maybe the majority) of experienced shooters refuse to degrade their lens' performance with two additional glass surfaces and rely on the hood to protect the lens.