Entries Tagged 'polarizing Filters' ↓

When a liner polarized light filter is align perpendicularly with another it blocks 100% of light, however when a 3rd filter is placed in between the 2 perpendicular filters at an angle some light is allowed thru. Why is this possible

see the applet in the link
lon-capa.org/~mmp/kap24/polarizers/Polarizer.htm

i have a 70 -300 mm lens and im going to buy a polarizing/uv filter, can you suggest what size filter i need to buy

thanks

On the rim of your lens with the other numbers there's a circle with a line through it followed by a number.

Like (symbol – circle with line thru it) 58.

That's the size of your thread, buy a filter that size.

It should depend on the kind of lens you have (make and model, etc). if its the Canon 70-300, its a 58mm. Sigma's 70-300 also has a 58mm filter. not sure about the Nikon/Sony models.

Google the specification of your lens. It will be listed there

The most useful filter for landscape photography is the polarizing filter. unlike other filters, e.g. neutral density (ND) or graduated ND filter,  there is no way to emulate polarizing filter effect in Photoshop or any other graphic editor.

Polarizing filters are very easy to use – you just rotate the front element and see through the viewfinder how image changes.

Note that the sun position is very important for polarizing filter effect – polarization is most effective at  90° to the sun, i.e. sun should be to your side or above you, not behind or before you to take full advantage of polarizing filter. that means that polarizer is completely useless when shooting sunset sun.

• Sky darkening. a polarizer cuts off the polarized component of light in the sky, increasing contrast with the clouds.
• Water – polarizer suppresses reflections on water and makes it transparent
• Eliminates other reflections – from metallic surfaces or glass. Also it removes reflections on vegetation (grass and leaves) making them more saturated.
• Improves saturation, contrast, even removes the haze to certain degree for distant objects.
• You can use it as a Neutral Density filter as well, especially when shooting running water or waterfalls

The most interesting and important part of the post – you can skip everything else and look only at photo. please note that you should move your mouse over images to see examples with and without polarizing filter.

Baspa River, near Manali, Himachal Pradesh, India

I think this photo is a good example as it illustrates all effects of using polarizing filter:

• Compare the sky – with polarizing filter sky becomes darker and there is more contrast between blue sky and white clouds
• Water becomes transparent and we can see stones on river bottom
• Leaves become more saturated and rich green as we remove blueish color cast from sky.
• Distant mountain gains more contrast

Cascade of Bhagsu waterfall. Bhagsu, Himachal Pradesh, India

You can see that on the image shot with polarizer all reflections on wet stones are completely eliminated, and the image has much more contrast. Leaves became more saturated too.

Here polarizing filter acted as ND filter too slowing exposure to 1 sec to get nice water blurring.

It is not obligatory to rotate the filter all the way to eliminate all reflections – you can stop halfway. for example, for image above I liked this intermediate position of filter – stones are not so dark but water became more transparent.

Though the image with polarization filter undoubtedly looks better, I didn’t like that reflections on stones completely disappear and they become too dark, it looks unnatural. Therefore I turned the polarizer half way – it preserved the stones, but at the same time made water transparent and foliage more saturated.

Wide angle lenses

Be careful with wide angle lenses.

• Firstly you should remember that any filter (including polarizers) can cause vignetting, so the filter mount ring should be thin.
• Secondly for lenses wider than about 24mm (in 35mm film terms) polarizing filter can cause uneven darkening of sky cause by different angle of sun position over the image – see the example below.

  This was shot at 10mm focal length on crop sensor camera – i.e. 16 mm in full-frame equivalent

  There is no way to avoid it, so for ultra wide-angle shots that include sky it is better not to use polarizers.

Polarizers ‘eat’ some light – up to 2 stops of exposure.  It means that if without filter you shoot at F9.0 and 1/100, with filter you will have to slow down to 1/25.

Also  as any other filter the polarizer degrades image quality (sharpness, contrast) to a certain extend.

In general I avoid using any filters, even UV or protection ones (usually I have enough protection from lens hood) as they all degrade image quality however when you are to use a filter then you should  try to get the best ones as their optical quality varies. Therefore I advise you to buy a good brand polarizing filter (Hoya, B+W), the best one that you can afford.

There are two types of polarizers: Linear and Circular. Circular polarizers ( CPL) are designed to not confuse the autofocus or metering systems on modern SLR cameras, so this is the type you should buy. however I have never seen any linear polarizers in shops so probably you wouldn’t buy wrong type.

I have heard a good review of Hoya HD polarizing filters, they have a very good coating that resists fingerprints and they lose less light – about 1 stop instead of usual 2 stops. Hoya is one of the most respected filter brands, and if you can afford it, go for it.

The bottom line  is:If you are shooting landscapes and don’t have a polarizing filter – go and get it!

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