RSS Feed of latest blog postsDecember 2011 - Using Filters
| Category: Despatches | 01 December 2011 |
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Solitary figure on the beach at dawn, Bamburgh Castle, Northumbria. Canon 1Ds mkII, 24-70mm lens @ 25mm, 1/5th sec @ f14, 0.6 ND grad hard filter. Choosing the right filter for the conditions is dependent on the contrast in the image. Here a 0.6 ND grad hard filter perfectly balances the tones top and bottom. |
Filters are the most basic of photographic tools. Graduated neutral density filters, or grads, are a landscape photographer’s best friend; absolutely essential for balancing the exposure between the mud and the cloudy bits. And straight neutral density filters are a vital necessity when I need to slow the world down, lengthen exposures and use a bit of movement to add a je ne sais quoi to slightly sterile images. Breaking waves, swaying trees, wafting grass, bustling people, speeding rickshaws; a bit of motion blur can often transform a picture. The way I use filters has changed since the film era, but the absolute necessity of carrying a comprehensive set has not. Here's a set of filters that I consider to be the perfect combination, one that enables me to subtly control contrast and prolong exposures in all sorts of different lighting situations.
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Essentially graduated neutral density filters are contrast control devices that enable us to maximise the exposure for the landscape to retain all the valuable shadow detail under the rocks without losing the drama in the heavens. They are of use to all those location photographers, not just landscapers, who have to deal with burnt out skies. Moody skies can make or break a landscape picture. Now there are many who think that in this digital age of HDR and exposure merging low tech sheets of resin placed in front of the lens are redundant; it can all be done in post production, can't it? Yes, Photoshop has a range of digital filters built in, but if the detail in the sky has been lost no amount of Photoshop wizardry can bring it back. It is true that the option of locking off the camera on the tripod then doing multiple exposures to be subsequently merged is a useful one, I do it often. High Dynamic Range software takes this a stage further, automating the merging to a point that a staggeringly extreme contrast range can be compressed and recorded. In comparison filters are a relatively crude solution to the contrast problem, so why not go down the high tech route and save on having to fork out on expensive filter kits?
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The Drakensberg Mountains, South Africa. Canon 1Ds mkIII, 16-35mm lens @ 21mm, 0.6 sec @ f14, 0.9 ND grad hard plus a 0.9ND ProGlass Standard filter. With the tree on the left blowing in the wind exposure merging was out. A 0.9 ND grad filter held the detail in the dramatic sky whilst the straight ND prolonged the exposure enough to enable me to convey the wind motion. |
Pre-dawn on Day 6 in the Royal Natal National Park; I stick my head out of the tent and scan the lightening sky. Cloud from horizon to horizon, it doesn’t look promising. But the old puritan work ethic forces me out of the damp sleeping bag and up the hill as I trudge on yet another dawn patrol. I’m extending the tripod legs more out of habit than hope, how long do I give it before heading back to the soggy tent? The Drakensberg mountains have been delivering a nightly deluge for the last few days; hot African sun on the bare rock of the harsh landscape builds huge towering cumulonimbus through the day. By nightfall the angry clouds are intent on ruining our barbecues and blighting my plans for dawn shoots. But today there’s a fresh breeze blowing and the cloud cover is starting to marble, the odd gap appears. Maybe, just maybe there is hope. I set up the camera on the tripod and check my default settings. This breeze could be interesting, the greenery is swaying nicely; let’s make the most of this. I dial in ISO 50 and reach for two filters; the 0.9 ND to slow the exposure, and a 0.9 ND grad to hold back the sky. I toy with the idea of exposure merging, but with the tree that cuts the skyline swaying in the stiff breeze I soon realise I’ll need to do this all in camera, with just one exposure. Merging multiple exposures with this degree of movement in the frame would make seamless joins impossible. This is in a nutshell is why filters are so necessary.
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The Cob at Lyme Regis at dawn with the Jurassic Coast beyond, Dorset. Canon 1Ds mkIII, 16-35mm lens @ 16mm, 8 mins @ f8, 0.9 ND grad hard plus 10x Big Stopper ND filters. Filters aren't high tech, but they work. |
The cloud cover is dissolving into ripples spreading across the sky; I’m getting excited now as the strong African light arcs across the landscape, transforming the scene. Its times like these that we photographers live for, not the hours hunched in front of the computer. If I can get the image as near perfect as possible in camera it cuts down on time lost in post-production. To do that, I need graduated filters. My approach is to try and record as much tonal and colour detail as possible in camera by using filters and then to just fine tune the balance between landscape and sky in post-production. It’s an approach that’s been honed over decades of shooting film, when it all had to be done in camera; it works for me. I’m not one for complex manipulations anyway, the best shots are the simplest and you can’t improve on nature. That’s why I can’t stand the artificial look of HDR images; they have a false Harry Potter look that I find tacky. It’s a cheap shortcut to producing pictures with impact, but for me that impact is gruesome. Doubtless countless readers will disagree, but there you go, I’ve nailed my colours to the mast.
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A barley field at dawn near Gubbio, Umbria, Italy. Canon 1Ds mkII, 16-35mm lens @ 22mm, 1/15sec @ f16, 0.9 ND grad filter. The distinct line of the horizon meant a hard grad was called for here, despite the ultra-wide angle and small aperture. |
Which filter to use and when is the Big Question. The age of coloured filters is past; there’s simply no point. I now have to admit to a shady secret; back in the 80s I occasionally used a graduated tobacco filter. We all did back then, just watch Top Gun! Nowadays the effect looks pretty dated and repulsive, but even if you did want that retro look there’s no need for coloured resin; that can all be achieved far easier and with more control in post production. Neutral density grads should be what it says on the tin; truly neutral, with no ugly colour casts in the sky. Which one to use will depend on the difference in exposure levels between the landscape and sky. In theory taking a reading off both, calculating the difference and choosing the applicable ND grad to perfectly balance the exposures is the way to do it. 0.3 of density equates to 1 stop exposure, so a 0.6 ND has a 2 stop difference from top to bottom. In practice out on a cliff top it’s more of a subjective call aided by experience. Using Live View to position filters and asses their effect is very convenient. An over filtered sky will be immediately apparent looking too heavy, whilst an under filtered sky will be a mass of blinkeys losing highlight info while the landscape still appears dark. If in doubt try a few combinations, asses and learn.
The one question that pops up time and again is; hard or soft? When using neutral density graduated filters which degree of gradation to use and when seems to be a perennial dilemma. I’m afraid I’m going to disappoint you now by fudging the issue; it depends on so many factors.
Firstly, lets just clarify what I’m on about. ND grads can have a very gradual, or soft transition from top to bottom, clear to dense, or a more pronounced, hard transition. Focal length, depth of field and aperture are all considerations when deciding which to use. I could say when using medium to long lenses with medium to large apertures and shallow depth of field use hard grads and with wide-angle lenses at small apertures with lots of depth of field use softs. It’s not a bad general guideline, but in a barley field in Umbria with my 16-35mm lens at 22mm my Canon is set at f16; the depth of field extends from the barley just centimetres from the front element all the way to Perugia, and yet I’m using a hard 0.9 ND grad, so clearly I’m talking bollocks. Ultimately, the choice of hard or soft will depend on the composition. For this shot I have a definite line along the skyline to lay the grad, the image essentially divides into two halves exposure wise and I’m using the grad filter to balance them. So the hard v soft debate is clear as mud, isn’t it? Just consider this. I use hard grads 90% of the time. If I could carry just one filter it would be a 0.6 ND grad hard. And as to which to use and when, well, you’re just going to have get out there in a crop field at dawn and experiment. Well, what else would you rather to be doing at 6am on a Sunday morning?
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Twilight over Praslin from the La Digue, Seychelles. Canon EOS 1Ds mk II, 17-40mm lens @ 17mm, 2.5 secs @ f22, Lee 0.9 ND plus 0.6 ND grad hard filters. Slowing exposures enough to record movement isn't always easy. How much movement is desirable is purely subjective. Here I chose to retain some of the surface texture of the water with a modest 2.5 sec shutter speed. |
A long exposure of waves breaking around rocks is a tried and tested formula that I’ve been hooked on since college days. Back then it seemed the height of creativity, now I feel it’s a bit of a cliché, but there are times when it just cannot be resisted and this is one of them. I’m stood on the shore of the idyllic tropical isle of La Digue in the Indian Ocean at dusk. My EOS 1Ds mk II is on the Giotto with the wide angle zoom set at 17mm as I strive to use as slow an exposure as possible. Now I really hope the boffins who knock up cameras back in Japan are reading this, because I don’t think they really understand our needs. They may think we all want cameras capable of ever-higher ISO settings, and some sports wallahs who shoot tennis by candlelight may. Personally I’ve never gone higher than ISO 1600. But there’s a significant army of us who like movement in our images; babbling brooks, blurry monks, scudding clouds and lapping waves are all vital weapons in our armoury. And with digital cameras with default ISO settings of 100 or higher it’s often difficult to slow exposures enough for any kind of movement to be apparent. The one aspect of working on large format film that I miss is that with an aperture of f45, a 0.3 centre-weighted filter (necessary because of the exceptionally wide coverage of the format), Velvia 50 film and reciprocity law failure exposures of several minutes were the norm, and the resultant movement effects were part and parcel of the feel of images shot on this format. My Canon can go down to ISO 50, but even so I’m often struggling to slow exposures enough to convey our moving world. Maybe one day they’ll make DSLRs capable of going down to ISO 6, but until then neutral density filters are a must for all of us hooked on motion blur.
As the sun drops over the Seychelles I’m exposing as the waves crash on the rocks below. With a 0.9 ND filter on shooting at the lens’ minimum aperture of f22 I can achieve a shutter speed of a few long seconds for the waves to surge and produce the desired mercury effect, as my old man calls it. I’m using 2 filters, the 3 stop 0.9 ND plus a 0.6 ND graduated to hold back the sky. Normally I try not to use more than one filter; to get the very best out of the sensor’s resolving power I need as little glass in front of the lens as possible. But sometimes you just have to, so the optical quality of the filters is crucial. Incidentally this is why I don’t adhere to the common practise of keeping a UV filter permanently attached as protection. Why fork out on an expensive lens only to compromise its performance with unnecessary glass?
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Even with an ISO of 50 and a 0.9ND filter slow exposures of several minutes are impossible until near darkness. With the shutter open for minutes clouds float through the sky and across the frame, giving an ethereal feel to pictures. The filter needed for these interminable exposures is so dense it appears opaque. The 10x ND slows an indicated 1/8th sec exposure down to 2 minutes, opening a whole new world of motion blur. A 1 second exposure becomes a 2 minute marathon; time to open the shutter and go for a pint while the pixels react to the feeble light permeating the dark glass. Composition and exposure calculations are all conducted before fitting the filter and locking the shutter open on the B setting. It’s fun.
And finally let’s hear it for the good old polariser. With direct sunlight sidelighting a scene the intensity of the colours in the vegetation and sky can be enhanced by rotating the filter. I don’t always use it in these situations, but I wouldn’t be without one. Filters aren't sexy, but they're crucial to add the final ingredient to your brilliant conceived and crafted images. |
