Happy summer (southern hemisphere friends, happy winter…)

Summer. Hence Sun. Right? So you need a polarizing filter for your lenses?

Yes, this is a good filter to have. A polarizer, as you know if you have been reading, actually does stuff:

  1. If you turn it to the correct angle, it makes the sky go darker (best at one angle, roughly perpendicular to the sun).
  2. It removes reflections (non-metallic reflections, like those on the surface of water).
  3. It can often help saturate colours (especially greens, like in vegetation).
  4. Fringe benefit: it darkens a little (usually, about a stop), so it acts like an ND filter. But just a little.

Here, a polarizer. In picture 1, it lets through polarized light (emitted by the LCD screen). In picture two, it is rotated to let through less. In picture three, it is rotated to allow even less polarized light to enter; and picture 4, none.

Below, the same while looking at the sky, which emits polarized light as well as unpolarized light: no polarizer; a polarizer rotated to allow in most polarized light; and one rotated to allow in almost no polarized light.

You will hear many people talk about “circular polarizers”, as opposed to “linear polarizers” You need a circular one for a digital camera. Let me explain.

A linear polarizer is just a polarizer. It lets through all, or none, or some amount of, polarizer light. But polarized light like this can confuse your camera’s AF and exposure sensors. So a circular polarizer is one that has two layers: the polarizer, followed by a filter that makes the light circularly polarized (basically, unpolarized). That way, no bad effect on the AF anmd exposure sensors.

This also allows you very easily to see whether your polarizer is circular: a circular polarizer only works one way. Turn it around (screw threat in front), and it does not work. Because the second filter makes the light basically unpolarized, so that the subsequent polarizer does not do anything.

So if your polarizer works the same whether you look through it one way or the other way, it is a linear polarizer, and will give you problems.

Here’s a polarizer taking away reflections (again, only off non-metallic surfaces):

Note that a polarizer can give you issues with mirrorless cameras. My Fuji x100, for instance, does not show the real effect when I use the electronic viewfinder. Beware!

Finally, a sequence with the polarizer turned to let progressively less polarized light in (using the Fuji x100):

You will note in the last images that part of the sky is darker than other parts of the sky. Yhis is becuse, as said earlier, teh angle matters. Parallel to the sun (i,.e.. the sun is behind you or in front of you) the polarizer does very little; at 90 degree angles it does a lot more. The only solution: use a longer lens.

And the last note: if you have only one polarizer, you can use only one lens? Nope. here, I used a large thread polarizer, a 77mm, simply held in front of the tiny x100 lens. Where there’s a will…


Have you had a look at my five e-books? All are over 100 pages long, well organized, illustrated, and a great source of information that gets you started immediately. Head over to learning.photography now!

Polarize it.. don’t criticize it.

Look at this shot of this morning:

And now look at this:

Look at the sky, and the cloud. More saturation on the blue. More separation between cloud and sky. More definition in the tree.

Because for the second shot I used a polarizer.

  1. Put it on the lens.
  2. Turn baby turn – until you see the desired effect.
  3. This effect is strongest 90 degrees perpendicular to the sun, i.e. when you are shooting 90 degrees to the right or left when the sun is behind you or in front. It is weakest parallel to the sun, i.e. when the sun is exactly behind you or in front of you.
  4. Do not leave the polarizer on – it eats a few stops of light. Only use it when you need it, and remove afterward.
  5. Do not combine with other filters, or vignetting may result.

Do you have a polarizer in your bag? If you live in a place where the sun can shine, you probably ought to.


Filter or hood? Which one trumps?

A reader emailed me this question:

First of all, I really enjoyed your Travel and Photo Journalism presentation on Saturday, thank you for some great information. Also the Flash Presentation was very informative.
I use a Canon XSI with a Sigma 18-200mm as a walk-about lens. The lens has a good lens hood, however I also have a circular polarizing UV filter on the lens and , with the lens hood on, I have difficulty adjusting the filter.  I typically don’t use a tripod so I run out of hands and fingers at the wrong time! Because of this complication I don’t use the Hood most of the time, any suggestions as to the benefits of the hood vs. the filter if I can only use one.

Good question, and one that may be useful for others too.

I still advise using both… I have a 70-200 and with the hood it’s quite tricky to adjust the polarizer: but I still do it quite often.

So I would say:

  • Lens hood: always. For stray light as well as for damage protection.
  • Polarizer when you need it (when the skies are blue, etc, or you want to reduce reflections, or you need to cut light).
  • Both when you can, and especially when you are shooting against strong light

I feel the reader’s pain… it’s one of those things where we wish it was different – but it isn’t… 🙂