Blog | 29 - Speed it Up
| bokeh photographic (Alistair Grant): Food & Drink Photographer; Commercial Photographer, Product Photographer & Packshot Photographer; Event Photographer; Portrait Photographer; Corporate Photographer & PR Photographer; Engagement Photographer & Wedding Photographer and Photography Training Courses in Cambridge, Huntingdon, Peterborough, Bedford, St Neots, St Ives and London. Freelance Photographer & Freelance Photography Services in Cambridgeshire, Bedfordshire, Northamptonshire, Norfolk, Suffolk, Essex, Hertfordshire and across the UK. | |||
 
|
Alistair Grant Freelance Photographer Cambridge & London |
||
|
bokeh photographic: Blog No: 29 → TIP: Click any image to view in LightBox |
|
||
|
|||
|
|||
|
|||
|
|
|||
|
Speed it Up One of the most exciting aspects of photography is to stop time i.e. freezing movement at a particular point in order to see ‘stopped detail’ that our eyes and brain can’t distinguish and can only perceive as motion. Although most amateur photographers fall into the trap of thinking a fast shutter speed is the best way to freeze movement, using flash is often a better option. Nevertheless, whilst freezing action with flash can produce stunning images it can be tricky due to the limitations of established flash technologies not to mention the failure of many photographers to understand how flash works. If I have previously shot a Food & Drink Photography assignment for you where action has been stopped in order to reveal detail you will have direct experience of the considerable lengths I had to go to in order to overcome the limitations of conventional flash technology i.e. my generally invalidating manufacturers' warranties through hotwiring various bits of kit to capture pancakes mid-flip, drinks mid-pour, flour mid-sift and, on more than one occasion, to capture sherbet mid-explosion. To avoid invalidating warranties (as well as significantly shortening the setup time for shoots) I have now invested in the very latest Insulated Gate Bipolar Transistor (IGBT) high-speed studio flash. Whilst I am going to miss fiddling around with screwdrivers the performance of these strobes has greatly impressed. This out-take is from a recent shoot for Gourmet Brownie: producers of the most delicious hand-baked brownies. Despite strong ambient light the IGBT high-speed strobes allowed me to completely freeze the action of 64 eggs being rapidly cracked into a bowl in just a minute or so - just look at how sharp the 'moving' parts of the image are. How does the technology work? I look for an extremely clean and exceptionally crisp image when aiming to freeze action whilst shooting high-speed flash. In other words, no motion artefact and no ghost trails; otherwise what’s the point of employing an expensive high-speed flash unit? In (highly simplified) terms, high-speed flash achieves clean and crisp images by switching on very quickly but also switching off very quickly. This can be explained by considering flash discharge curves: plots of energy intensity (vertical axis) against time (horizontal axis). When a conventional flash unit is discharged, energy stored in the capacitor causes rapid ionization of the xenon gas within the flash tube which results in a very steep upward curve in energy (and therefore flash brightness) followed by a much less steep downward curve back to zero NB: this happens so quickly we perceive only a brief burst of light. Two indices are important when considering flash discharge curves: t.5 is the time taken for 50% of the total flash power to dissipate to zero whereas t.1 is the time taken for 90% of the total flash power to dissipate to zero. Although flash manufacturers tend to quote t.5 data as these appear more flattering t.1 is arguably more important. A flash discharge curve with a ‘long tail’ (i.e. a slow t.1) means that the flash continues to emit light longer after discharge and that light, although declining, may be sufficient to cause movement artefact. The only reliable way to freeze movement without artefact is to use a flash unit that has a short tail (i.e. a fast t.1) or even a flash that truncates the downward energy curve back to zero – i.e. a flash that not only achieves peak energy output very quickly but a flash that drops to zero energy output very quickly. This is exactly the technology employed by my IGBT high-speed strobes which boast, at minimum flash power, a t.1 of 1/35086 sec compared to 1/900 sec for my (top of the range) standard flash. I mention power as t.1 times are affected by flash intensity as is flash colour temperature. However, as I’ve probably frazzled your brain with all the above I’ll leave explaining these, and camera sync speed, to a future blog post. I haven’t yet even gone close to pushing the kit to its maximum performance so watch this space. Bring on the pancakes, drinks, flour and sherbet! |
|||
|
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. |
|||
|
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. |
|
||
|
bokeh photographic - Alistair Grant | Freelance Photographer | Cambridge, London, UK 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] |
|||
