LENS filters, such as polarisers and neutral-density (ND) grads, really need a feature in themselves, but don't be intimidated by these very useful accessories. The judicious use of lens filters can transform your landscape photography and they are not really that complicated when you get used to them.
Getting used to polarisers
If you've not used filters before, circular polarisers are a good starting point - they can deepen blue skies and reduce glare and reflections, but have other uses. They are great for getting more accurate shots of wet rocks, for example, or ensuring wet foliage doesn't reflect the sky and take on a blue tone. As they simply screw on to your lens, many people keep polarisers on all the time, but don't get lazy and activate the effect when you don't need it. It's also important to avoid using a lens that is too wide for a polariser, as you can end up with an ugly 'hot spot' in the middle of the image (in a blue sky, for example).
GRADUATING TO ND GRADS
For many landscape photographers, ND grad filters are the go-to filter. They are essential for balancing the sky with the foreground to get an even exposure, and for getting contrast and exposure levels right. When putting your ND grad in place, especially when presented with a straight horizon, it's easy to become complacent. It's tempting to just pull the grad down to roughly the point where the horizon meets the sky and then shoot away.
This, though, can lead to far too dark a horizon, so be sure to really study the scene and pay particular attention to positioning the grad line correctly and carefully. Should a feature - such as rocks or a cliff - protrude into the horizon line, you might want to set the grad at an angle, so these features aren't too dark in the final image. You also need to spend a bit of time studying the density of ND grads.
Remember, the darkest part of an ND grad varies in exposure value (EV) between filters. One with a lighter density might cut out only 1EV of light, whereas the darkest can cut out as many as 4EVs of light. You don't want to use a grad that's too strong for the scene, which might result in the sky appearing darker than you'd like. Selecting the correct filter can be confusing, as manufacturers give them different names. For example, an ND4 is the same density as a 0.6ND - both reduce the exposure by two stops. A good starting point is an ND4 or 0.6ND, which is suitable for the majority of scenes, but this varies depending on the strength of the light. Another useful lens filter for landscapes is a screw-on Variable ND filter, handy for getting 'slow water' effects at long exposures without hopelessly overexposing the image.
A 0.9ND filter is more suitable here, than the 0.3ND option, which is not as strong
|Lee Filters app|
|If you use a Stopper filter, there's an app for iOS and Android that allows you to pick which ND filter you're using and accurately calculate the new exposure straight from your mobile. When you open the app, you're given the choice of 6 stops (Little Stopper), 10 stops (Big Stopper) or 15 stops (Super Stopper) from the top. With the filter selected, scroll a wheel on the left to match your camera's metered shutter speed (range 30secs-1/8,000sec) without the filter. Simultaneously, a wheel on the right automatically spins to give the correct exposure with the filter attached.|
Who needs filters?
Photo-editing tools such as Photoshop and Lightroom now replicate the effect of filters, particularly NDs. Will this ever replace the physical versions? 'I'm not sure the software tech is there yet,' says Jeremy Walker. 'My theory is that light transmitted through an optical surface looks different from something created on a computer - you need the information on the fi le to start with. The dynamic range of sensors is improving, but there is still a need for physical ND grads in the short to medium term.'