Exercise 4: Shutter speed- or why 1/1000th of second really matters

I'm not sure why but I really struggled thinking about photographing something for this topic. Sure I could have photographed varies moving objects like buses which would fill the frame (see below) but i wanted to do something slightly different with the cliche which would get the message (and picture) across in a more obvious, yet subtle way. It finally dawned on me... if there  is one subject  that has been photographed to death to appear creamy and still in one frame, and forceful, even violent, in the next, it is most surely water. The sea is a few miles away, and then some, from the big Smog so I thought I'd try photographing fish swimming in a tank with an air bubble volcano.... I think the result was a success.

First the obligatory bus shot:

Yes, there is a bus in this picture. but all you see of it are the lights. I took it on a very narrow aperture (f32) and low ISO and kept the shutter open for 10 seconds... the results, a Waterloo bridge devoid of traffic and people except for the lights of the cars and buses. Tell tell sign of the bus... the streak of light in the top right hand corner. There we go, movement and light all in one!



The actual pictures:
The pictures were taken at an ISO of 800 and automatic aperture. Most of them resulted in an aperture of f1.8 but certainly as the shutter speed decreased, the camera compensated by reducing the aperture value accordingly  in order to maintain an exposure value of . some observations were expected, brighter photographs as the shutter speed decreased, less detail and blurring. A little less expected was the illusion of speed. The rate of air  flow was constant, so the increase in the number of bubbles, at first gives an impression of increased air flow. Not so, it seems what happens is that the shutter is open long enough to capture more bubbles without distortion, of course this reached a threshold between 1/250 sec and 1/60 at which point distortion restored the old assumptions.

Photo 1:

1-TV4000 or 1/4000th of a second exposure. This resulted in a clearly defined bubble column and almost no fish! atmospheric shot but not much detail.

Photo2:

TV1000 or 1/1000th of second shutter speed.
A lot more detail and the  fish are clearly visible. Bubble column remains static and frozen in time. the shutter speed is now slow enough to capture the light escaping from the top of the tank which creates a ghostly flame effect

Photo3:

 Tv 250 or 1/250th of a second shutter speed.
Again a lot of detail but fish are still sharp and the bubble column, remains fairly distinct, but if you look at the two previous photographs it seems like more bubbles are now present in the column... not so, the rate of air being pumped in to the tank is fixed all that seems to have happened is that the shutter is now open long enough to catch more of the bubbles in the column.

Photo4:

TV60 or 1/60th of a second shutter speed.
At this speed we now start to see movement. the fish are becoming less sharp, and the bubbles appear to have taken on a more elongated shape, no longer round, most definitely cylindrical.

Photo5:

TV15 or 1/15th of a second shutter speed:
The bubbles are gone, in their place an eruption of air. The fish are loosing definition and form, well at least the fancier versions with flowing tails. The less flamboyant ones, the ones that can stay still remain in fairly clear detail.

Photo6:

 TV1" or 1 second shutter speed.
the illusion is complete. we now have air flowing up the stream at an impossible speed  given the dimensions of the tank. the highlights are blown out and the fish are disappearing before us, a few indistinct colours and shapes remain, ghostly fish but the escaping light has changed shape from flames to a halo.