Blog | 72 - Big It Up
| Freelance Photographer in St Ives Cambridgeshire: Food & Drink Photography; Commercial Photography, Product Photography & Packshot Photography; Event Photography; Portrait Photography; Corporate Photography & PR Photography; Engagement Photography & Wedding Photography and Photography Training Courses in Cambridge, Huntingdon, Peterborough, Bedford, Ely, St Neots, St Ives and London. Professional Photography Services in St Ives, St Neots, Huntingdon, Bedford, Peterborough, Ely & Cambridge. | |||
 
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Alistair Grant Freelance Photographer Cambridge & London |
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bokeh photographic: Blog No: 72 → TIP: Click any image to view in LightBox |
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Big It Up One aspect that immediately becomes apparent when speaking to those enrolling on bokeh photographic Training Courses is that people don’t fully understand light. A case in point is the Inverse Square Law which can be regarded as the photographic equivalent of football’s offside rule i.e. although everyone mentions it, few can explain it, and even fewer appreciate the subtleties of it. Everyone gets that the further an object is away from a light source the less light will hit that object, after all that’s just common sense, but only a minority comprehend the rate of light drop-off e.g. most assume that an object 2 metres away from a light source receives half the light compared to an object a metre away and an object four metres away receives a quarter of light. In fact the object at 2 metres receives a quarter of light compared to the object at a metre and the object at four metres only receives one sixteenth of the light. Whatever the real (or perceived) lighting problem it seems that the default response is to purchase ‘bigger & better’ equipment. I’ve lost count of the number of times I heard people state that 'all will be ok' because their new flash unit etc. is 'as powerful as a lighthouse'. We will return to exactly how a lighthouse works but it’s probably best to first consider the ultimate light source i.e. the sun. For the purposes of this explanation let’s assume that the power of our light source is fixed: we are deliberately avoiding the ‘bigger & better’ mentality. On a sunny cloudless day light from the sun is direct and unhindered and so shadows are prominent on the opposite side of any object facing the sun. However, when a cloud obscures the sun, although the total amount of light getting through the cloud to the ground is diminished, shadows are reduced. They may even be completely eliminated on a very overcast day. This is because clouds act as a physical barrier between the light source and the area of earth illuminated by the sun. Although historically high power bulbs (typically 1,000-3,000 watts) were used in lighthouses no bulb, however powerful, can account for the far reach of a lighthouse beam. A lighthouse also uses a physical barrier in order to modify light: specifically a special type of lens called a Fresnel lens named after the French Physicist Augustin-Jean Fresnel. A Fresnel lens has a distinctive stepped appearance due to ridges in the lens surface where each ridge bends light slightly more than the one before it so that light rays are concentrated into a perfect parallel beam that can be seen for a far greater distance than even the most powerful lightbulb alone. In fact, as the optical performance of Fresnel lenses improves much less powerful bulbs are now being installed in lighthouses across the world. Although clouds and Fresnel lenses are both physical barriers their effect is very different. Clouds scatter light rays from the direct light source (the sun) which softens shadows and so produces ‘soft’ light whilst a Fresnel lens concentrates light rays from the direct light source (the bulb) which hardens shadows and so produces ‘hard’ light. In photography unmodified artificial light whether flash or continuous is non-diffused and so just like direct sun produces hard light with distinct shadows and characteristically high contrast. Photographic light modifiers (i.e. umbrellas, soft-boxes, diffusion panels or even just a piece of horticultural fleece) work on the same principle as clouds in terms of acting as a physical barrier to scatter or ‘diffuse’ light from a direct light source to produce softer light. However, there is another important way of modifying direct light for photographic purposes. Again let’s first consider the sun. When a cloud obscures the sun the entire light source (i.e. the sun together with the cloud) effectively becomes larger relative to the subject being photographed. The larger the light source relative to the subject the softer the light whereas the smaller the light source relative to the subject the harder the light. This can be hard to get your head around. With a radius of 432,450 miles, a diameter of 864,938 miles and a circumference of 2,713,406 miles the sun is big – it’s the largest object in our solar system – but as it’s so distant we generally don’t notice a drop-off in intensity because of the Inverse Square Law. Whilst we obviously can’t alter the position of the sun we can take advantage of clouds which effectively create a mega-sized natural soft-box where the diffusing physical barrier at the front of the soft-box (i.e. cloud at anywhere between ground level to 12 miles away in the upper reaches of the troposphere) is much closer to the ground than the light source at the back of the soft-box (the sun at an average distance of 92,955,807 miles away). We adopt the same principle when utilising modifiers such as a photographic soft-box where there are three main ways of altering the relative size of the light source to the subject: i) moving the whole soft-box closer to the subject; ii) using a bigger diameter soft-box; or iii) using a deeper soft-box whose design produces even softer and more evenly distributed light. To reiterate, in addition to scattering light from a direct light source by using a diffusing physical barrier such as a soft-box, altering the relative size of the light source to whatever is being photographed can also help soften hard light from a direct light source thus reducing shadows and contrast. Whether to diffuse direct light is a case of personal preference. Although shadows have been almost totally eliminated in most commercial professional photography over the last decade they are steadily making a comeback! I for one think this is a good thing on the caveat that this isn’t an absolute dichotomy (i.e. shadow or no shadow) as there are almost an infinite number of steps on the incremental scale between hard and soft light. Finally, is buying a flash unit ‘as powerful as a lighthouse’ a good strategy? Probably not for the vast majority of photographers as high-powered units limit the ability to work at wide open apertures and in confined spaces. My best advice is to instead invest in light modifiers although an equally effective yet cheaper method of softening light is to use a decorator’s sheet or horticultural fleece from the pound store! Of course, as a professional photographer covering a wide range of photographic scenarios I don’t necessarily follow my own advice! In addition to various continuous lights I own several sets of low, medium and high-powered specification studio strobes which lets me light all types of photographic scenarios. Rest assured however that in addition to my ‘manufactured’ (and overpriced?) umbrellas, soft-boxes, diffusion panels etc. I have miles and miles of horticultural fleece. NB: The lighthouse pictured is the iconic 1792 Orford Ness lighthouse designed by William Wilkins, decommissioned in 2013 and now under the stewardship of the Orford Ness Lighthouse Trust, which unfortunately is at risk of imminent collapse due to costal erosion although the Trust are aiming to save it. The picture was taken in August 2019. In September 2019 high tides and strong winds led to collapse of the bungalow just visible adjoining the lighthouse; the place where we sat and had lunch in August. |
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Call Alistair Grant on 07775 365507, Email [email protected] or click Booking Enquiries if you have any questions or would like to make a booking. |
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bokeh: "the aesthetic quality of the blur produced in the out-of-focus parts of an image produced by a lens" Freelance Photographer offering Food & Drink Photography Cambridge; Commercial Photography Cambridge, Product Photography Cambridge & Packshot Photography Cambridge; Event Photography Cambridge; Portrait Photography Cambridge; Corporate Photography Cambridge & PR Photography Cambridge; Engagement Photography Cambridge & Wedding Photography Cambridge and Photography Training Courses in Cambridge. Also covering: Huntingdon, St. Ives, Ramsey, St. Neots, Peterborough, Bedford, Stamford, Newmarket, Sawtry, Alconbury Weston, Brampton, Hartford, Warboys, Houghton, Wyton, Godmanchester, Hilton, Hemingford Grey, Hemingford Abbots, Fenstanton, Whittesley, Yaxley, Needingworth, Somersham, Chatteris, Ely, Bar Hill, Grafham and Buckden. |
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bokeh photographic - Alistair Grant | Freelance Photographer | Cambridge, London, UK - Creative Natural Photography And Outstanding Customer Service At Competitive Prices - Food & Drink Photography | Commercial Photography & Product Photography | Corporate Photography & PR Photography | Portrait Photography (inc. 'Active Portraiture', 'Naturally You' & 'Poptraits') | Event Photography | Engagement & Wedding Photography | Photography Training Courses & Camera Tuition | Videography & Film Production Tel: 07775 365507 | Email: [email protected] |
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