Category Archives: Intro

Introduction

Exercise – Panning With Different Shutter Speeds

The aim of this exercise was to practice panning to track a moving subject, and compare results when doing so using different shutter speeds. In this case, the subject is a girl riding a bicycle. I tried to capture the photographic instant at about the same point in the subjects’ position relative to the camera and background, so as to make easier comparisons.

 

Photo 1 – 1/200th second

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At this shutter speed, motion is practically frozen, except for maybe in the spokes of the bike.

 

Photo 2 – 1/100th second

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Motion in the spokes now a little more blurred, as parts of the riders’ body, the feet particularly. Still able to keep a decent track of the subject.

 

Photo 3 – 1/50th second

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Spokes much more blurred, motion of the rider now more obvious, as is the background pavement.

 

Photo 4 – 1/25th second

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A good sense of the speed of the subject is gained in this image. Tracking was still easily maintained.

 

Photo 5 – 1/10 second

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Background elements now indistinctly blurred, and every part of the image suggests a subject in full motion.

 

Photo 6 – 1/2 second

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It now became somewhat harder to keep a track of the subject long enough for the long shutter speed to maintain an accurate register of the subject in motion.

 

Photo 7 – 1 second

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I considered this 1 second exposure to be at the limit of being able to track the subject and still retain enough detail and information as to be identifiable. Timing was also an issue, the subject moved rapidly enough that deciding when to click the shutter became increasingly difficult and several attempts had to be made.

 

I think the use or absence of motion blur in an image is entirely subjective. That is, whether it is  successful as an image in terms of its’ aesthetic quality depends on the intended purpose of the photo and the expectations of the image viewer. In the case of the exercises above I find that for the water spray, freezing the droplets enough presents a more interesting image purely for the fact that it’s a sight uncommonly seen. Water droplets don’t spend much time hanging around in mid-air to allow a viewer a chance to observe their quality. Whereas for the girl on the bike, a sense of speed isolates the subject from the background, and lends a somewhat warmer quality to the image in general, despite the conditions on that particular day being cold and overcast. So, the two photos I would choose for the preferred qualities mentioned above are:

 

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Exercise – Shutter Speeds

This exercise demonstrates the effect of varied shutter speeds has on the ability to stop motion, or not, of a given photographic subject. In this instance I use water sprinkling out of a shower head. The camera was mounted on a tripod and a Nikkor AF-S 50mm lens used as the lens. Initially due to low light conditions, I tried using a flash, but could only sync it up to 1/200 shutter speed. I then tried a single bright LED torch, hoping to provide a constant light source, mitigating the cameras’ tendency to compensate for varying shutter speeds by opening or closing the aperture to maintain a constant exposure (which it was only unevenly able to do).

 

Photo 1 – 1/800th second

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The camera tried to compensate for the generally low light condition and fast shutter speed but image still appears darker than was actually the case. Motion of the water droplets ahs not been adequately frozen.

 

Photo 2 – 1/500th second

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Blurring due to motion somewhat more apparent in this image.

 

Photo 3 – 1/100th second

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Photo 4 – 1/50 second

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Photo 5 – 1/10th second

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Photo 6 – 1 second

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Droplet motion now renders as an indistinct blur.

 

Photo 7 – 3 seconds

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One of the aims of the exercise was to find the slowest shutter at which the apparent motion appears to be frozen, and I have to say that even a 1/800th shutter speed did not seem to show this. I note however that using an on-camera flash, rather than the torch, at 1/200th shutter speed did freeze the action enough, as shown below:

 

Photo 8 – 1/200th second, with flash

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Exercise – Focus At Different Apertures

For this exercise, a series of photos taken with a fixed focus point but varying apertures sizes was required.

I chose an unusual carpet in my home that I thought with careful framing and positioning of the camera , might give obvious results, despite the random nature of the carpets’ colour and pattern.

First photo – aperture f/1.8 with the limits of sharpness indicated between the white lines.

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Second photo – aperture f/8:

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Third photo – aperture f/16:

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I think the above does show the effect differing aperture sizes has on the depth of field in an image.

Exercise – Focus With A Set Aperture

This exercise required the taking of several photos of the same scene at varying aperture settings. I chose a nearby Buddhist stupa that had a number of prayers wheels aligned in a way that would give useful results. I elected not to use a tripod for this series of photos, and I mounted a Nikkor AF-S 50mm lens on the camera. Aperture was set at its’ widest; f/1.8

First photo – near focus point:

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Second photo – mid-focus point:

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Third photo – far focus point:

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Of the three photos I prefer the one with the closest focus point. I think in an image like this, where there are several instances of a particular object or subject in view, a close focus point shows quite clearly what that subject actually is, and the detail on it is very discernable. Your eye is drawn immediately to the first prayer wheel, and then moves deeper into the image. Because the first wheel is in sharp focus, and given the very wide aperture setting, the last prayer wheel is deeply out of focus, or blurry, which is more pleasing to the eye. Whereas a mid-focus point only allows a somewhat milder blur quality to the first and last wheels.

Link to higher resolution TIFF image files

Exercise – Focal Length and Angle of View

I skipped the the first part if this exercise, due to the suggestion that it was unlikely to work with a digital camera.

Firstly I had to determine my camera’s standard focal length. The camera is a Nikon D5100 and according to the manufacturer has a cropped imaging sensor and therefore a crop factor of 1.5X. This would therefore give it a standard focal length of just over 38mm. I then mounted an 18-105mm Nikkor zoom lens onto the camera for this exercise.

The scene I decided to capture lay just outside my rear balcony. A new apartment block just completed in construction. Something of an eyesore actually, but useful at least as something quite definite in form and easy to measure against. The camera was mounted on a tripod for a repeatably stable from which to take the next series of photos.

First photo was at the cameras’ standard focal length – 38mm

38mm

When this photo was printed and then held at enough of a distance so that it appeared to be the same size as its subject, I measured this to be 35cm.

The next photo was at its’ widest angle of view – 18mm

18mm

I found this photo when printed had to be held at such a close level I think I ended up cross-eyed! It wasn’t practical to make a measurement, but I would say length somewhat shorter than my nose, about 4 cm

And the last photo at the narrowest field of view (or longest telephoto length) – 105mm

105mm

This photo had to be held at just beyond an arms’ length away to make the comparison, at about 95cm (does that mean I have short arms?).

When I printed these photos out on A4 sized paper I wasn’t sure whether to do so with a borderless reproduction, or as the print software determined a “100%” print size to be, which had quite a wide border. I opted for 100%. The images had to be straightened slightly in software. I very rarely print my photos, so it really was quite interesting to have actual photos in hand, even if they were printed on plain copier paper.

Link to higher resolution TIFF image files

Shutter

The shutter is a device, mechanism or electronic function in a camera, be it still or video, which limits the amount of time in which light is exposed on the focus area or plane, whether that be an electronic light detector or a frame of film. Typically it consists of a thin mechanically driven plate that moves in and out of the path of light. Often it sits just in front of the focal plane or focusing area.

Being able to control the shutter speed determines a number of effects in the resulting image:

  • The most important being that of the ability to stop or freeze action. Typically, the faster the shutter speed, the less obvious the effect of motion blur, especially of subjects moving at high speed. High shutter speeds also generally limit the amount of light falling on the focus area, useful for controlling exposure in brightly lit environments.
  • Slow shutter speeds are useful in situations where there is a need to boost or increase the amount of light falling on the focusing area, as in low-light conditions. A drawback to this though is an increase in motion blur, especially if the camera is not mounted on a stabilising device like a tripod. Slow shutter speeds also can be used for artistic effect, as when there is a need to suggest the motion of a subject.
https://i0.wp.com/upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Focal-plane_shutter.jpg/266px-Focal-plane_shutter.jpg

A mechanical focal plane shutter – source: wikimedia.org

 

 

 

 

 

 

 

 

sources: wikipedia.org

Aperture

The aperture of an optical system is a measurement of the size of the iris or light opening and therefore of how much light is allowed to the reach the point of focus. It does not refer to the mechanism itself that controls or determines that same size.

The aperture is measured in f-stops with small f-stop numbers indicating when the aperture is set at its’ widest opening, and small f-stops when set at it’s smallest. A wide aperture allows the maximum transmission of light through the optical system to the focus point, where as a narrow aperture allows for less light to reach the focus point. The effect of these aperture changes, wide to narrow and vice-versa on an image are two-fold.

  • One is the effect varying aperture sizes have on light gathering power. Wide apertures allow for greater light-gathering power in low-light situations, as would be useful in dimly lit or night-time environments, whilst narrow apertures limit the light gathered, as would be useful in artificially brightly lit or daytime environments.
  • The other is that the field of depth, or apparent depth of focus in an image is either shallow deep, depending on the aperture size. Wide apertures give rise to shallow fields of depth, where only a small proportion of the image is in clear focus, whereas narrow apertures give rise to deep fields of depth, where most of an image, front to back is in clear focus.

The aperture in a camera system is controlled by an aperture mechanism. This is a device, usually made up of multiple interleaving blades, whose position is adjusted to determine a given f-stop number. The typical range of f-stops for a lens can be between f/1.4 and f/16.

 

https://i2.wp.com/upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Aperture_in_Canon_50mm_f1.8_II_lens.jpg/237px-Aperture_in_Canon_50mm_f1.8_II_lens.jpg

An aperture mechanism for a 50mm lens. source: wikimedia.org

 

source: wikipedia.org