When And How You Should Use Filters

Lavender Field, Lincoln, Nebraska

I shared a general “rule of thumb” to stand with the sun behind you (particularly for mountains) during sunrise and sunset a while ago, but that doesn’t mean we can’t create beautiful images shooting sideways or into the sun.  We just need to be aware that due to the uneven light – too bright in the sky, and too dark on the ground – you’ll more likely generate disappointing images if you don’t manage light correctly.

So how do we solve the problem?  This is when filters can help.

I have not used filters extensively in the past because I split my time between people, animals, landscape during travels, and filters are almost exclusively used in landscape photography.  Plus I'd like to keep things simple.  Even I typically bring two camera bodies, three lenses on the trip, I tried to minimize my weight by carrying as little as possible (here's more detail on what's in my camera bag). 

Nevertheless, here are some tips about when and how to use filters.

Two Common Scenarios To Use filters:

1. Darken the sky

Darken the sky to even out light, particularly when the sky is much brighter than the ground.  You want to create similar lighting conditions for your subjects and prevent part of your image from being over-exposed (eg. for the sky) or under-exposed (eg. for the ground).  Lee Natural Density Filters come with 1 stop (ND 0.3), 2 stop (ND 0.6) or 3 stop (ND 0.9) filters.  The sharper the sky/ground color contrast, the bigger stop filter you should use.  See following examples.This scenario sometimes could be replaced by digital editing in Adobe Lightroom, using graduated filter mask, which I will explain below.

Depending on how much you want to darken the sky, you can use one filter or several filters that stack on top of each other.  See my camera set up below.

filter illustration

2. Long Exposure

Another situation I use filter is to photograph ocean, lakes, rivers or waterfalls etc.  The purpose is to darken your image and force the camera to execute a longer exposure in order to smooth the water surface.   The longer the shutter, the smoother the water surface will look.  Typically in this scenario, I use Lee or B+W 10-stop filter. You will need a tripod and remote shutter release in combination of filters in this case.The following 6 images can give you a clearer understanding how filters can smooth the lake surface and get rid of the waves.

How To Use Filters

The first scenario above is relatively simple, you operate your camera as you normally use it.  In the second scenario using 10 stop filter, your viewfinder could be pitch dark and the camera wouldn't be able to find anything so your lens couldn't autofocus.  I use the following process:

1. take a picture using auto focus on your lens without the 10 stop filter.  Remember your shutter speed.

2. switch the lens from AF (auto focus) to MF (manual focus)

3. switch your camera mode to bulb.  Dial to the same aperture you just used

4. use an iPhone app called ND Timer.  It will give you the accurate shutter you need to use (you should be able to calculate the shutter yourself basically double your exposure 10 times).  The app just saves your time.

5. use a remote shutter release to execute the shot

Alternatives To Using Filter

1. Use Digital Filter

Using filter could be a tedious process, but the result could be exhilarating.  If you are new to photography and don't yet have a tripod, do not invest in filters.  Rather, you can try to use "digital filters" in your computer and understand what filters do to your photos.

In this video tutorial, I have shown how you can use Adobe Lightroom's graduated filter function to darken the sky.  It's almost exactly the same as using a real filter.  In fact you can adjust the filter's graduation level to 1.5 stop or 1.25 stop, and widen or narrow the graduation area, which is more sophisticated than the physical filters.

Digital filters can be applied in the 1st scenario above but not the 2nd unless you are a photoshop expert.

2. Photograph In Twilight

Another alternative is to photograph during twilight in very dim light situation.  In this scenario, since the surrounding is very dark, you need a camera with strong sensor, a tripod and remote shutter release to execute a long exposure.

I mentioned the need of a remote shutter release several times here because most cameras can only allow up to 30 sec exposure.  For any longer exposure than 30 seconds, you need to force it with a shutter release.  This is a separate topic and I'd be happy to explain in another post.

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