The Blue Blot - Or Why You Shouldn't...

on May 28, 2015

Those of us from North America who remember ARIZONA HIGHWAYS* were always amazed at the wonderful colours in the images. Deep blues in the skies, strong reds and yellows in the landscape. We all wanted that in our pictures - even if we were taking pictures in British Columbia in the murk season. What was the trick?

The trick turned out to be simple:

1. Use Fujifilm Velvia 50 film.
2. Get the printer to pour more ink into the press.
3. Move to Arizona.

I opted to move to Western Australia and the murk season stayed in Canada, so I was ahead already. Then with the advent of digital I could pour more saturation into the computer easily. And finally I discovered the circular polarising filter - this allowed me to make the skies blue and the seas green.

But when I got a very wide angle lens and tried to do the same trick with it that I was able to do on a standard focal-length lens - I ran into another of those optical facts of life. A circular polariser on a very wide angle lens only de-polarises part of the image.

The lens sees wider than the effect of the filter - it is the simple fact that the polarisation of the light in the sky is imperceptible when looking directly at or away from the sun - but is at maximum when you are looking 90º from the sun. You get a big blue blot in the middle of a blank sky.

What to do - take the filter off. Or position the blue blot where it makes a dramatic statement and cover up the other blank bits with buildings or trees. Cactus, if you are in Arizona...

Note - this is also a good hint to look at the graduated neutral density systems that Cokin and Lee make. They can make skies darker evenly, if dark skies are your thing. If you would like to have permanently dark skies move to British Columbia. They've got a murk season there that rivals anything in the world.

* Travel promo magazine.