Tuesday 3 May 2016

Taking sharp photos - birds

The content of this post may seem a little contrary to convention at first, but it does also make perfect sense from a scientific perspective.

There are many factors which have an impact upon the sharpness of images, from the resolution of a camera's sensor to the clarity of the atmosphere, but the one thing that I repeatedly find has a particularly profound effect is Sunlight. Many birders now have a proclivity for taking photos as the age of digital photography and system aids has made photography within the reach of everyone regardless of skill or bank balance. Dad used to tell me how purchasing a camera in 1960s - 70s was a massive decision, as even mid-range equipment was months' worth of wages rather than days'/weeks'. Also the time frame between taking the photos and using the photos was significantly longer back then - I did briefly start off with film for perhaps 6 -7 years before digital photography really took over; the anticipation of waiting for pics to come back after sending off a roll of film in the mail is something I still remember well. Comparing this with what we have now is mind-blowing; a BOC (back of camera) shot or a digi-scoped shot with a phone (phone-scoping) can be posted on Twitter and have reached in excess of 10,000 people within a few hours. That's a pretty remarkable change.

Back to the propitious conditions which are conducive of taking sharp photos:
There is an incredibly common misconception that you need strong and/or direct Sunlight to take 'good' photos. Granted, there are scenarios where direct Sunlight brings out different colours in a subject - take the Glossy Ibis for example; this species can appear as a near-uniform charcoal grey colour in the shade, yet can exhibit shiny purple and green tones when viewed in direct Sunlight. In this example the bird appears far more coruscating to observe in direct Sunlight, but not necessarily to photograph.

Here's a few of the downsides of strong Sunlight for photography:

  • Severe exaggeration of highlights and shadows of the scene i.e. whites are too bright, and shadow areas lack detail
  • You need a clear view of the subject. If photographing from behind a tree, with the light source coming from behind you, there can be shadows of the tree obscuring the subject
  • Angle & direction of the Sunlight - to minimise the effects of the aforementioned highlights and shadows (first bullet point), ideally the Sun needs to be directly behind you, with the 'angle' being the light source, photographer and subject all in line (so not very often the case)
  • Heat haze - this is the big one for ruining photos and making them unsharp; various surfaces 'reflect' heat and this introduces significant atmospheric interference between photographer and subject.
I have tried to illustrate this below with the recent Hoopoe (Musbury). The symptoms are slightly exaggerated here as the scene is side-lit (partially backlit) but it demonstrates the concepts well. The pics were taken at the same range of about 25ft. The heat haze effect of softening the details is increased with distance from the subject, so with this pic being close up, it's actually minimising this effect to an extent.

As well as the problems as per the annotations, the above image is generally soft - purely a result of heat haze.

The below image was taken shortly before, when some clouds passed over and obscured the Sun. The difference is rather puissant.

And a close crop of both of these really emphasises the difference in detail & sharpness:

It baffles some people that when I want to go somewhere to photograph birds, I look to the forecast with the honest hope that it says cloudy/overcast; I'm even happy if it says rain so long as it's not prolonged spells of torrential rain.

Sunlight isn't always a photographer's enemy, but this is exception rather than rule. Not all situations produce severe heat haze however i.e. a bird sat up in a tree can look fairly sharp in a photo even if taken in direct Sunlight. Also back-lighting can be used to good effect to produce images with an artistic aesthetic, but the applications of this are fairly limited. Grass and water are amongst the worst offenders for producing heat haze, so it's the photography of grounded birds which causes the most difficulty.

I'll do another 'photography' type post soon, unless there's some more birds of interest to report on. The wind direction does look favourable this week so we could have another influx of migrants...

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