Kood 100mm Series Neutral Density Soft Grad Filter

Hard or soft?

After determining what density of filter is required, the next decision is whether it should have a hard or soft graduation. Hard graduation filters, which quickly change from clear to dark, are the most popular choice as they allow the density transition to be positioned on the horizon where the sky is often

the brightest. However, these filters can be spotted easily on subjects that cross from the darker part of the image to the bright area. A tree, for example, may appear to get darker halfway up its trunk.

Soft graduation filters have a more subtle transition so it is harder to spot that a filter has been

used. They are useful for images with subjects that cross between the dark and bright areas of a scene, perhaps darkening a bright puddle of water within a landscape. As soft grad filters are less obvious to the eye, they can be trickier to position correctly because it is harder to see their effect in the viewfinder.

Tiffen Color Grad

Filter selection

A 0.6 ND grad, which reduces the exposure of the brightest areas by two stops, is a good starting point and is generally sufficient for daytime use in sunny weather. However, a 1.2 ND grad, which reduces exposure by four stops, can be useful at sunset when shooting towards the sun. While multiple filters can be used to darken bright parts of the scene further, this increases the number of reflective surfaces in front of the lens, which increases the chances of introducing flare and reducing contrast.

The easiest way to check which density of filter is required is to set the camera to aperture priority mode at the aperture setting you wish to use. Then use the spot or partial metering option to take light readings from a midtone in the foreground and an area of middle-level brightness in the sky. The difference in exposure between these two readings gives the strength of the filter required to balance the exposure across the frame. For example, If the foreground requires an exposure of 1 /60sec at f/16, while the suggested reading for the sky is 1/250sec at f/16, giving a difference of two stops, a 0 6 ND grad should be just right. Alternatively, the camera's histogram view can be used to check whether the ND grad has enabled all the sky detail to be retained. This is indicated by the trace just reaching the far right without a large peak at this end of the scale.

How to use an ND grad

There are two ways to use a graduated neutral density filter. The first is to set the camera to manual exposure mode and, without the filter in place, set exposure values for the foreground. The image is then composed and the ND grad slipped into place. With SLRs it is usually possible to see the darkening effect in the viewfinder. With a slot-in filter, take time to push the filter up and down again until the transition falls exactly where it is needed - on the point that the light and dark areas of the scene meet. With a landscape this is usually at the horizon.

Modern metering systems lend themselves to a second, simpler method of using an ND grad. With the image composed in the viewfinder (or on the LCD), the filter is slid into place as before and the shot taken using the settings the camera has calculated to be correct for the scene as a whole. The histogram view will confirm whether all the highlight detail has been recorded If the peak is towards the middle of the scale, a less dense filter can be used.

Reader offer

SRB-Griturn is offering all AP readers who buy a graduated neutral density filter set in June a free filter wallet. The sets include four ND grads (0.3,06,0.9 and 1.2) and are available in two sizes: 67x110mm and 85x110mm. Both sets retail at £46. To get your free wallet, simply call 01582 661 878 and quote reference code 'AP/SRB/ND' when you place your order.

^pE»^ AamA There are two key things you want from a I graduated neutral density filter. First, it should be neutral, so it doesn't introduce any unwanted colour cast, and second, it should cut out the correct amount of light (in this case reducing the brightness by 104). The following details the results from my test of 0.6 ND grad filters from six different manufacturers. I checked the filters' neutrality by photographing a sheet of white paper in the sun (with a custom white balance setting) with and without the filters in place over the lens. I then compared the colour of images taken with and without the filters using the Eyedropper tool in Adobe Photoshop CS3 to find the change in the red, green and blue (RGB) values. The greater the difference between these values, the greater the colour shift. Even a small shift impacts upon the midtones and can be noticeable in a landscape.

Cokm offers slot-in hard and soft ND grads in four sizes: A, P, Z-Pro and X-Pro, wit h the A-series being the smallest (67x67mm) and X-Pro the largest (100x150mm). One, two and three-stop grads are available in each size. Our tests reveal that the ND4 filter is a little less dense than we would expect and that it imparts a slight blue colour cast.

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LEE FILTERS 100x150mm 0.6 ND grad (hard) £52.00

Lee Filters, Central Way, Walworth Industrial Estate, Andover, Hampshire SP10 5AN. Tel: 01264 366 245. Website: www.leefilters.com

Lee Filters can provide hard or soft ND grads with densities of 0.3,0.45,0.6,0.75, 0.9 and 1.2. Lee's graduated filters measure 100x150mm, giving plenty of scope for positioning the gradation. I found the 0.6 ND filter reduces the exposure by a lit tie over 2EV and there is only a slight colour shift towards the blue part of the spectrum.

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SRB-GRITURN 85x110mm 0.6 ND grad (hard) £12.50

SRB-Griturn Ltd, Unit 21D, Icknield Way Farm, Tring Road, Dunstable, Bedfordshire LU6 2JX. Tel: 01582 661 878. Website: www.srb-griturn.com

SRB-Griturn's slot-in filters are compatible with either the Cokin A- or P-system, and are available with hard or soft gradations in four densities: 0.3.0.6,09 and 1.2.1 found the sharp transition of the hard grad easy to position and the 0.6 density reduces the brightness almost as it should, but there was a significant blue cast to the images.

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TIFFEN 4x4in 0.6 ND grad (soft) £205.00

Tiffen Europe Ltd, Enterprise House, Weston Business Park, Weston on the Green, Oxford 0X25 3SX. Tel: 01869 343 835. Website: www.tiffen.com

Though it is mainly known for its round filters, Tiffen also produces glass rectangular filters in a variety of formats, and a glass Tiffen filter compatible with the Cokin P-system costs in the region of £127.1 found the 4x4in 06 ND test sample to be the most neutral in this group. The brightness reduction is also only a little more than 104.

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COKIN P-SERIES 84x100mm ND4 grad (Medium)

Intro2020, Unit 1, Priors Way, Maidenhead, Berkshire SL6 2HP. Tel: 01628 674 411. Website www.intro2020.co.uk

FORMATT HITECH 100x150mm 0.6 ND grad (hard) £44.00

Formatt Filters, Unit 23, Aberaman Park Industrial Estate, Aberaman, Aberdare, Mid Glamorgan CF44 6DA. Tel: 01685 870 979. Website: www.formatt.co.uk

Formatt offers two sizes of filter: the Hitech 85 (84x110mm compatible with Cokin P-system) and Hitech 100 series (100x100mm or 100x150mm). Hard and soft ND grads are available. I found the 0.6 ND grad is quite dark, reducing brightness by 120 (in Photoshop) rather than the anticipated 104. There is also a noticeable blue cast.

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KOOD 100x125mm dark grey grad £23.00

Kood International Ltd, Unit 6, Wellington Road, London Colney, Hertfordshire AL21EY. Tel: 01727 823 812. Website: www.kood-international.com

Kood International offers ND grads with transitions described as halfway between a soft and a hard graduation in three sizes: two that are compatible with the Cokin A- and P-system, plus 100x125mm. I found the transition is very gradual and this filter is the least dense of all the filters tested here. There is also a slight green note to the images.

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  • SANNI
    How to use neutral density graduated filter manual setting?
    7 years ago

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