Digital Photography & Image Manipulation

Thursday, 14 November 2013

Movement, Composition, Texture and Patterns

I found this pdf very useful in understanding the use of movement, composition, texture and patterns as creative techniques in photography:

http://staffweb.worc.ac.uk/photomodule/cdme2011&3011/Session-4/Creative-camera-techniques.pdf

Light

Light is the paint with which you paint a photograph. Without light even the
best digital camera will be lost, as that is what a camera is. It is a device for
capturing light and converting it onto a 2D plate such as a CCD or celluloid.

The chart above represents the approximate colour and temperature values

for the visible spectrum of light. The red end of the spectrum has the longer

wavelengths; conversely the blue end has the shorter wavelengths. Colour

temperatures are worked out on the basis of the colour metal acquires at a

certain temperature. The values are approximate. The key colour

temperature is noon daylight, which is –5,400K.

The light you will use for photography comes in many flavours Fluorescent

light is hard to pin on the colour chart as it gives out many wavelength.

Flash photography, mostly will have a narrow white band of even

wavelength, daylight can produce light of almost infinite wavelengths.

Daylight is what most photographers take pictures in Fig (1.0) represents

dawn, which is a very good time to shoot because of the light quality.

At Dawn the light from the sun has to pass through a large area of

atmosphere, which essentially scatters the wavelengths of light. This is also

influenced by pollution in the earth’s atmosphere which colours the light.

When Light reaches its azimuth in the sky at 12 mid-day the lights angle

approaches that of 90 degrees to the earths surface, as a result the light

travels through less atmosphere, and is purer. It usually produces washed

out pictures with little shadow detail. The light appears bluer and hotter.

Reflections tend towards blue.

Sunset is essentially the same as sunrise with the sun at a shallow angle to

the earth, as we view it. If you were to shoot a highly reflective surface

such as a lake at this time the colours appear muted, and contrast increased

to silhouette level.

Of course this all relies on the weather conditions while shooting the scene,

you are always at the mercy of cloud formations, or rain to diffuse or reflect

the light before it reaches the camera.

When taking pictures outside several problems may occur

This opening shot (alternative) from the sound of music shows that the

background is lit correctly but a shadow falls across the subjects face, if

exposure is taken correctly either the subject is dark or the background is

too light.

Conversely if the sun is behind the camera you get a better fall of light on

the character but the image may be ‘washed out’ and the background may

be darkened to compensate for an image that compensates for too bright a

foreground.

The best situation is where the light falls to the side or to the front/side of

your subject so that you get an all round exposure from the available light,

nice shadows on one side of the object or the other (which gives good

contrast), generally a pleasing image.

So to reiterate, try to take photos in the morning or afternoon out of the

mid-day sun as it generally very harsh and gives a flattening effect to the

pictures, try to get a good contrast of shadows in the image.

Diffusion

I wanted to say a small piece about diffusing light, this passing of light

through a translucent object breaks it up and so it isn’t as harsh. Clouds are

very good for this they diffuse the light wonderfully, softening shadows and

giving a gentler feathered edge to light.

Indoor lighting (using available light)

Windows are ideal for portrait photography, especially if there are dust

motes in the air, as you get a volumetric effect, like light breaking through

a cloud you get a shaft of light. Watch for over-exposing the light itself

rather than the subject.

Reference:

http://staffweb.worc.ac.uk/photomodule/cdme2011&3011/Session-4/Light.pdf

Lenses

Aperture and focal length

The two terms to make sure you understand when choosing a photographic lens for

an SLR are the maximum aperture and the focal length. The focal length indicates

the angle of view (sometimes called the field of view), while the maximum aperture

limits the fastest shutter speed usable, as well as the depth of field.

Lenses are marked with their aperture and focal length. If you understand what these

markings means you can choose the correct lens for the effect you want to achieve.

Lets look at an example: 18-105mm f/3.5-5.6

What does this mean?

18-105mm is the focal length of the lens. This tells us that it will ‘zoom’ from

18mm, a wide angle shot, to 105mm a telephoto shot (a magnified shot). Look at

the example shots below to see the effect on the picture.

f/3.5-5/6 is the maximum aperture of the lens. Why are there two ‘f’ numbers?

Well the aperture varies as you change the focal length. So if you are ‘zoomed’

out to 18mm this lens will give you an aperture of f/3.5, if you are zoomed into

105mm it will only give you an aperture of f/5.6. This would mean it is classed as

quite a slow lens (see further on in the notes for an explanation about fast and

slow lenses)

Lets look at another example: 50mm f/1.4

What does this mean?

50mm is the focal length but in this case it is fixed meaning you cannot zoom and

therefore the field of view is always the same. This is often called a prime lens.

f/1.4 is again the maximum aperture of the lens. There is only one number this

time as the lens cannot ‘zoom’ so the maximum is always f/1.4. This would be

classed as fast lens (see further on in the notes for an explanation about fast and slow lenses)

Examples of fields of view and how it’s affected by focal length:

Usually a specialist lens known as a wide angle. A wide angle lens lets you get more

into the frame but distorts perspective – which can be a nice effect. (You can go even

wider into what is called a ‘fish eye’ lens). Good for emphasising scale.

Still classed as wide angle but often within the range of a ‘kit’ lens. I.e. a zoom lens

often sold as part of a kit of parts with an SLR. So for example the Nikon D60 is sold

with a kit lens of 18-55mm, the D90 with an 18-105mm so both could take this shot.

Considered the same as the human eye – all ‘kit’ lenses will cover this range

Classed as telephoto, i.e. things are magnified

Again telephoto but magnified more. Lenses that cover a range of focal lengths are

classed as ‘zooms’. A typical zoom might be 100-300mm. There are lenses that will

go to 1000mm and above but these are big and expensive. 1000mm+ lenses are the

type of lens sports photographers and paparazzi might use.

‘Fast’ and ‘Slow’ lenses

You will sometimes hear lenses described as ‘fast’ or ‘slow’ lenses. Here’s why…

A fast lens lets you take a shot using a higher shutter speed as it will allow you a

large aperture (thereby letting more light in). So for instance a 10mm f/1.4 lens would

be considered very fast and allow you to take shots in low light. This large aperture

would also give you very shallow depth of field.

A slow lens on the other hand has quite a small maximum aperture letting less light

in meaning a slower shutter speed for a given exposure. So for instance a 200mm

f/5.6 lens would be considered slow but with considerable magnification.

Lenses get more expensive the faster they are for a given focal length. So a budget

100mm lens might give you a maximum aperture of f/5.6. A professional lens might

give you f/3.4 on the same focal length. How’s this done? The lens quality is greater

so more light gets through and the lens is a bigger diameter (again letting more light

in). But this means the cost of the lens higher.

Depth of field and lens choice

To achieve a shallow depth of field with selective focus you need a large aperture as

you know. So what lens should you choose? Well if you were working close to the

subject (say for candid photography) you would generally use a prime lens with a

maximum aperture in the region of f/1.4 or f/1.6.

The catch with this sort of very large aperture is focusing. Getting the point you want

in focus on a very shallow depth of field is hard. On the D40X and D60 you have to

do this manually. On the D90 however you can use auto focus but your focus point

needs to be very carefully targeted.

Shot at f1.4 using Nikon D90 selectively focused on the hand (Targeted auto-focus)

Shot at f1.4 using Nikon D90 selectively focused on the face (Targeted auto-focus)

Shot at f1.4 in close up using Nikon D60 (focused manually). Very shallow depth of

field so hard to focus particularly when the dog keeps moving!

Polarizing filter

Polarising filters change the way that your camera sees and treats light. Particularly – when using one you’ll notice a change in how your camera sees reflections and glare. As a result it also has the ability to change the vibrancy of some colors in shots.

Without a polarising filter

With a polarising filter

Water – When shooting a picture of water adjusting your polarising filter will mean you see into the water differently, cutting out glare and even changing the colour of the water. For example when I was snorkelling off a boat off the coast of Indonesia a few years ago I took a series of photos (on my film camera) using a polarising filter that made the water look crystal clear and a bright blue color. Without the filter the shots had nowhere near the same impact with a big reflection being picked up off the top of the water and a more murky color.

Sky – Similarly, the color of sky can change remarkably using a polarising filter. Rotating the filter you’ll see a blue sky change from a light pale blue color to a vibrant and deep blue color (depending upon where the sun is). A polarising filter can cut out a lot of the smoggy haze that is often in city shots.

Color – Polarizing filters cut down the reflection that many objects have (even those that you might not think reflect at all). This makes the colors of some of these objects more vibrant. For example out in the garden you might notice foliage on trees looking greener than you would get without the filter.

Other Reflections – Shooting through glass can be a real challenge at times and using a polarising filter can definitely assist in cutting down distracting reflections or glare. Similarly photographing shiny objects (like a new car for instance) with a polarising filter will change the way reflections are treated.

Polarizers Change Exposure

One factor to consider with polarising filters is that they change the exposure needed for a shot. When you see a polarising filter you’ll notice that it looks quite a lot like a sunglasses lens. The filter is dark and works by cutting our some of the aspects of light (similarly to sunglasses). As a result less light gets through to your image sensor and you’ll need to either use longer shutter speeds, a larger aperture or to beef up your ISO setting to account for this. The difference that you’ll need to account for is 1-2 stops. It’s for this reason that you won’t want to use a polarising filter at night.

Using a Polarizing Filter
These filters are easy to use. Most of you will use a circular polarizing filter which allows you to adjust how it impacts your shots but simply rotating the front element of the filter. As you do this you’ll notice that colors and reflections in your shot change. Once you've got it to a point that you like simply take the shot.

For the greatest impact try to keep the sun at 90° to you (ie to your side – not at your back and not shooting into the sun). This will help your polarizer to have the greatest effect.

Be aware that shooting in low light, overcast days or at night with a polarizer is not advisable – it’s like wearing sunglasses indoors and will cut down the amount of light getting through to your image sensor.

Varied Results

The extent that polarising filters work varies from situation to situation (often dependant upon the amount of sunlight) so it won’t have a massive impact in all situations – but in some (especially bright sunny days) the impact can be quite staggering.

References:

http://digital-photography-school.com/how-to-use-and-buy-polarizing-filters

http://www.cambridgeincolour.com/tutorials/polarizing-filters.htm

My attempt

I had a polarising filter booked out so I thought I'd test it out. Unfortunately it hadn't been bright enough in the day to make use of it so I thought I'd test its uses for managing exposure. There was a full moon so my thoughts were that I'd be able to capture a nice exposure of the bright moon without a tripod if I used a filter to limit the amount of light entering the lens.

Here's a few I managed to get with a high ISO. The filter alone wasn't really enough to get satisfactory shots. With the use of a tripod, I should have used the smallest aperture available with a longer exposure which would have allowed me to use a much lower ISO resulting in far less noise.

Next time I'll book out a bigger lens (hopefully the 500mm) and tripod to achieve much better results.

Here's a few tests I got showing the element inside a light bulb with the use of the filter, a UV filter might have been better for this purpose but I found it interesting nonetheless:

Task 2 - Autumn

We were asked to experiment with the shutter speed and aperture priority modes with an Autumn theme. Here are some of the shots I came up with:

I had a quick go at creating a vertical panorama to test an idea:

I like the idea of the image, especially due to the blossom tree on the left, however to execute it properly I need to use a tripod and a polarizing filter. I'm also considering trying it with a wide-angle lens to achieve a slightly distorted perspective, an effect I like with vertical panoramas.

First shots

To start getting to know the camera controls I booked out a d90 to experiment with. Unfortunately the weather was terrible so I experimented briefly indoors.