Aspicus and the Art of Photography

From Snapper to Shooter (hopefully)

Project 4

Shutter Speeds

What: The aim of this project is to explore the impact of shutter speed on exposures involving a moving object.  The project involves taking and comparing several images of a moving object at different shutter speeds and commenting on the results.
Where: In my garden (as usual it seems).
When: Mid-morning in March.  A very bright and sunny day.
Why: I found it quite surprisingly difficult to find a suitable subject for this project.  I tried a few ideas.  For example I would find a subject (e.g. cars driving along a road), but then it was either so bright that I could not get a very slow shutter speed, or it was so dark that I could not get a very quick one.  What I really needed I think was a neutral density filter. In the end, I thought that a relatively rapidly moving object would show the difference between different shutter speeds in fairly bright light.  A tennis ball being bounced against a wall seemed to do the trick.
How: Camera settings were manual, focal length 32mm, ISO various (depending on how fast I wanted the shutter speed to be), various aperture (see below), and various shutter speeds. I used a tripod in order to ensure that the basic frame of the shots were the same between shutter speed variations.  Images were captured as JPEG using the rapid frames-per-second of the D300 to capture the tennis ball.

The images

I started off with a 1 second exposure and then approximately halved the shutter speed with each shot.  The shot was of a tennis ball being bounced against a wall.

1 second shutter speed:

f/29, ISO200

1/2 second shutter speed:

f/20, ISO200

1/4 shutter speed:

f/14, ISO200

1/8 shutter speed:

f/10, ISO200

1/20 shutter speed:

f/6.3, ISO200

1/50 shutter speed:

f/4.2, ISO200

1/100 shutter speed:

f/4.2, ISO500

1/200 shutter speed:

f/4.2, ISO1000

1/400 shutter speed:

f/4.2, ISO2000

1/800 shutter speed:

f/4.2, ISO3200

1/1600 shutter speed:

f/4.2, ISO6400

Observations

From the 1 second exposure to the 1/20 seconds exposure the tennis ball is hardly visible.  It is just about visible in each shot (you may have to look very closely in the 1 second shot). At 1/40 seconds exposure the ball is firmly visible as a round object, if a little blurred.  This blurring gets smaller and smaller until at 1/400 seconds the ball looks stationary, and with faster shutter speeds more and more detail of the ball become sharper and sharper.  At 1/1600 seconds the ball is relatively detailed.

In terms of my favourite shot (and I will be the first to say it’s not the most awe-inspiring of series), I think I prefer the 1/100 seconds exposure.  This is because the shape is recognisably a tennis ball, but there is the sense of motion, of speed, of the ball.  For shots at a faster speed than this, there  is no real sense of motion (there is some spin on the ball – but this just makes it look unfocused).  For 1/50th and slower the ball just becomes a smear, and at very slow speeds it starts to disappear all together, and it is not clear what the shot is actually of.  This disappearance of the ball is interesting – presumably it is because the light from the background is that much greater than the light of the subject (the ball) which is moving rapidly through the frame, that the image of the ball is just flooded out.  I wonder whether a shot of a busy road with long enough shutter speeds will render an image empty of cars or people?  I imagine such a shot will require a very strong ND filter.

Also, note the barrel distortion of the lens.  Look at the lines of cement towards the top and bottom of the images and notice how they bow away from the edges.  Either than is barrel-distortion or I need a new wall.

Further Questions

1. Why does the subject disappear at slow enough shutter speeds, and can this technique be used to take a photo of a busy scene and remove all the moving objects (e.g. people, cars etc).

What I’ve Learned

1. Slower shutter speeds gives the impression of movement to objects travelling through the frame.

2. However, very slow shutter speeds can mean that the subject may disappear from the scene altogether if it is travelling fast enough, or the exposure is long enough.

3. Therefore, for rapidly moving objects, the shutter speed needs to be balanced against the speed of the object, using ISO, NDs and frames-per-second.

4. The 18-200 lens has noticable barrel distortion, even to an amateur such as myself.

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15 March 2009 - Posted by | Projects

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