Tips for using a CPL effectively


Some of you who follow our work would know that a circular polariser (CPL) lives on the front of our lenses. Recently, we’ve made a change to using Nisi filters which means that for the most part, we use the kit CPL included with their variety of holders. As with many phases of development in photography, using a CPL is one of those subjects where once you discover it, there’s an initial trend to blindly use it no matter the situation! (Didn’t we all go through that to some degree with ‘HDR’ ??) With time and experience though, one becomes a little more judicious and refined with its use. I would say that a CPL is used for the majority of our images and I thought I’d share some do’s and don’ts about their use.

What does a CPL do?

  • Cuts out reflections : particularly useful for forest scenes.
  • Deepens natural colours : useful for most scenes.
  • Acts as a very light ND filter (1-1.5 stops): useful for seascapes in bright light.
  • They are potential rainbow killers! Be wary of having a CPL on with wide angled lenses if you think a rainbow is even a possibility.
  • It’s also another piece of glass that could interfere with image quality , particularly in moist situations and prolonged shooting. If I had to choose between polarisation for colours and a clean image, I would choose a clean image and remove the CPL.

Predawn light: A situation where I would be trying to avoid using a CPL since it acts as a light ND filter. For this scene, I was at iso 800 and did not want a shutter speed longer than 5-10 seconds or all texture would be lost. Hence I removed the CPL.

 

It’s generally a good idea to remove all filters (CPL included) when shooting for a sunstar.

 

Mornings with rain and breaking light lead me to prepare for a quick CPL removal ! If positioned incorrectly, a CPL may well polarise out the rainbow entirely or at least in part.

What do you do with the dial?

  • Its maximal effect is perpendicular to light source. If you point your index finger to the light source and poke your thumb out perpendicularly, the maximal polarisation occurs in the plane as you rotate your hand around.
  • If  your CPL has a dot on it, point that to the light source for maximal effect but use judgement depending on the presence of plain skies in particular.
  • Don’t forget to turn the CPL if you happen to change from landscape to portrait orientation (or vice versa) otherwise one of your images will have no polarisation effects!

In a forest situation, the light source is generally from up above. A useful starting point to achieve maximum polarisation is to have the ‘dot’ of your CPL pointing straight up in whatever orientation you are shooting. If your CPL does not have a ‘dot’ to indicate maximum polarisation direction, you may need to experiment for the best result.

Forest/waterfall scenes:

  • Use it to deepen the greens and allow a ‘see through’ effect to river beds.
  • Point the ‘dot’ on the CPL up to the sky.
  • Remove it if needing to keep foliage still with faster shutter, or alternatively, take separate frames with the CPL on at higher iso /larger aperture to allow adequate exposure at the desired shutter speed.
  • And remember (again), turn that CPL if you change orientation!

A forest scene with the CPL positioned to have minimal polarisation (dot sideways). Note the glare of the foliage and the presence of a waterfall reflection. The greens are also less vibrant.

The same scene with the CPL ‘dot’ turned upward. Note the vibrance of the greens and the removal of the waterfall reflection and see through effect to the creek bed.

Sometimes, to get the best of both worlds , polarised and unpolarised images can be blended such as in this example where the reflection is maintained along with the vibrant greens.

A perfect scenario for a CPL is a cloudy day with alpine streams of various natural hues. The CPL can really enhance the hues of the water while having no banding in plain skies to worry about!

Open skies:

  • Very good with long focal lengths to isolate your subject with blue skies.
  • Avoid using with wide angled images especially when perpendicular to light source (or expect to have to correct in post process) .
  • Use it to enhance detail in clouds : be wary of patches of open sky in the clouds themselves.
  • When in doubt with open skies, take the CPL off. It can be quite tricky to blend images with polarised and unpolarised images.

Enhanced clouds but note the darkened band in the blue sky perpendicular to the light source to the right of the image.

The sky is unpolarised in this version of the same scene but note that the reflections from the water have been removed by polarisation in a different plane.

RAW file of a wide angled image demonstrating the problematic band that a CPL can cause when shooting perpendicular to the light source.

The same scene as above but shot at a longer focal length. If your subject is perpendicular to a light source, shooting at longer focal length with the CPL turned to the light really can enhance the subject greatly without the same problematic banding that is seen with shorter focal lengths.

Not that this sky needed it, but the CPL certainly helps bring out textures in clouds.

Seascapes:

  • Can enhance natural colours and reduce glare off rocks.
  • Sometimes the glare or reflection shooting into sun is required/desired therefore you may not want to use the CPL.
  • Sometimes in bright light, you may be using the CPL purely as a light ND filter in order to achieve 0.3-0.5 second exposures in bright light.

Generally speaking, polarisation isn’t necessary when shooting seascapes directly into a light source, especially when shooting for sunstars.

 

A CPL in this situation may slightly enhance general colours but may also reduce colourful reflections. In any given situation, it may help you achieve a slightly lower shutter speed rather than stopping down to small apertures such as F22.

Conclusions:

  • I consider a CPL a very important part of a landscape photographer’s kit.
  • If your CPL does not have a ‘dot’ I would experiment and perhaps even mark out where the ‘dot’ for maximum polarisation should be as a time saver.
  • Forest scenes are where they truly allow colours to sing .
  • Beware situations where you would rather not use one : plain skies, sunstars, rainbow opportunities and shutter dependent low light scenes
  • Most importantly, you need to decide according to your shooting style and preferred subjects whether you invest in one. Lastly, if you do invest in one, consider using screw-on filters for shooting handheld. For tripod situations using a filter holder, I would recommend using the NiSi filter holder system which has the CPL as part of the holder itself (take this with a grain of salt as I am an Australian Nisi ambassador !)

Happy shooting all and I hope there was at least one bit of information there that was useful! We’re off the New Zealand 🙂

 

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Posted on September 19, 2017, in Australia, How we..., Photography and tagged , , , , , , , , , . Bookmark the permalink. 5 Comments.

  1. This so great! Thank you for sharing this. Very beautiful. Thank you for useful tips also.

  2. Very informative in so few words; plus the thousands in the pictures, of course.

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