Flight shots in twilight and the photographer's dilemma
Until
Wednesday I had never watched a barn owl. I had seen them occasionally but
that’s not the same thing: for me, watching isn’t just using my eyes and
binoculars but my camera too. I want the best photos that I can take. There are
three simple rules for taking good photos in natural light
1 use a fast shutter speed to avoid
subject movement and camera shake
2 use a small aperture for good depth
of field and good lens performance
3 use a low ISO setting for good
sensor performance
The problem is
that these three choices are mutually exclusive: the photographer's dilemma is choosing right compromise for the situation.
My situation was
the Ron Barker hide at Martin Mere WWT reserve just after 3pm, with a couple
of other snappers waiting for the owl. I had glimpsed it flying back to its
barn at 9.45am. The rest of the day had been dull, icy and unmemorable
so all my hopes rested on the owl when I returned to the hide.
For a flying
bird in good light, I like to set my D300s at 200 ISO and 1/1000s hoping to
have the aperture of my 500mm prime Nikkor at about f/8; I think that’s the
compromise that gives me the best chance. Obviously I couldn't chose these settings even for record shots of the
owl. When it reappeared I took some
shots at around 1/640s, f/6.3 and 640 ISO. Then I did some chimping (I love
that term) to check the images and histograms. As the owl was quartering the
far end of the field its image in the frame was very small. I decided to try
more focal length by fitting my 1.4 converter to make my 500mm f/4 lens into a
700mm f/5.6.
That change gave me a better image size, but the light was getting worse. My camera is set up for
shutter priority as I think that the shutter speed is the most important choice.
Could I risk a slower one? Fortunately owls do not fly fast and our barn owl’s
hunting strategy meant that it was frequently flying towards the hide, before
vanishing behind two hawthorns in the hedge. I knew I’d see blurred wingtips (at
least) unless I could catch a moment when the owl had a short glide. I caught
one here, 640 ISO, 1/320s and f/5.6 (the dark shapes in the background are
longhorn cattle).
That image
needed considerable cropping, but it was far better than any of my other shots. A
small subject moving in poor light is a tough test for an autofocus system and
I got very blurred results when I experimented with even slower shutter speeds.
By the time the owl disappeared after 25 minutes, I was working at 1600 ISO.
The other
photographers left while I was sorting out my camera bag and closing the
windows of the hide. Then the owl reappeared and sat on the fence at the bottom
of the field. It was 3.50pm and quite dark when it started to hunt again. I
removed the converter, set the ISO to 3200 (my camera's maximum value)
and shot a few more frames. After 5 minutes it flew over the hedge and behind
the hide. I ran to the other end of the hide and took a few more shots, this
time it came closer and gave a flypast before it disappeared (1/500s at f/4 and
f/5.6).
All these shots needed quite a bit of processing with Capture NX2 to reduce
the noise and to control the contrast and the colours, and then some minor retouching
with cropping and resizing using Photoshop CS5.
On reflection
I am quite pleased with these images, but I think I could have done a little better if
I had started by setting exposure compensation at -1/3 or -2/3 stop to give slightly darker
images with a more natural impression of the twilight. I tried to give a hint
of this in the processing, but doing it in camera would have been easier and
better and it would have eased the shutter speed/aperture dilemma a little. I also wish that
I had reduced the ISO for the final shots of the owl on the gate, as I could
have used a shutter speed of 1/200s for those.
Now I want another chance to try for better owl pictures.
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