Photography: The Basics

Introduction:

In essence the camera has not changed since photography began. Focusing a lens on the subject of your choice. Clicking a shutter and recording the scene on  material or device (sensor) which can be processed at a later date. Finally taking that image and producing a final image which is your vision of the original scene.

For me this is often forgotten. Especially in the white hot progress of the digital age. Just about every camera I have owned has had a user manual which had more pages than my previous one. Over the last few years I have endeavoured to “go back to basics” and currently my favourite camera has few automatic feature. This is obviously my personal choice and I’m not advocating it  for everyone. When I REALLY need to get an image I'm not averse to pulling out my big Nikon DSLR and letting full auto help me out.

But automation has its price and there are a number of situations which it will fail. Case in point is a firmware upgrade for my Fuji. Included is full face recognition and the ability to focus on a persons eyes. Tried it out on Jean…..failed…..She wears glasses. The reflections on the lenses prevented the camera from finding her eye - blurred portraits. Both my daughters also have glasses. Wonderful upgrade for me — NOT.

So this document is meant to introduce the basics of photography so that you can at least keep an eye on what automation is doing and critically decide whether its going to give you the image that you want and if not how to override it to produce that final image you have in your head.

Point to note is that I’m not a fan of flash. The equipment is expensive, heavy and to me specialised. I have a flash for my DSLR which I can use but its a last resort for me. You may have to look elsewhere is you want to go in that direction. I like moving fast, taking my photos on the move. Not posed. I prefer a blurred, noisy image than the starkness of a flashed image.

Camera Controls and Taking a Photo:

Lets consider a beautiful scene, The Sydney Harbour Bridge or the Opera House. Its a fine sunny day. Blue sky, few white puffy clouds and sparking water.  A must have photo for your remembrances.  Lets consider what happens to your camera in the following seconds.

Device Sensitivity:

Every photographic recording medium or sensor has a certain sensitivity to light falling on it. This is called ISO or ASA. What these stand for does not matter. Low ISO means the device needs a lot of light to perfectly record the image and high vales mean much less light. Roughing low ISO settings will produce a higher quality of image than a higher one. (Keep this in mind for later). A film would have an ISO rating. Digital camera can change the ISO setting for every picture and many can automatically do so.

• • • Sensitivity Values of ISO usually are 100 to 6400. - Your camera should indicate what value is being used and you should be able to change it- ideally quickly if required.

Lens Aperture:

Not only does a lens focus light onto the device (see later)  but also is used to determine the amount of light which hits the sensor. This is done by varying the size of the hole which the light has to pass through. This is called the Aperture. Obvious to say that a large aperture lets in more light then a small aperture! Aperture settings  are measured in F numbers or F Stops.

• • • F Stops values typically are F2 to F22. Traditionally the increments are F2.0, 2.8, 4, 5.6, 8, 11, 16, 22.  Each stop increment halves the amount of light hitting the sensor. There are optical and mathematically reason why these number are so strange but just accept them! Modern digital cameras can have any value between the two ends and the aperture can be set automatically. The minimum and maximum values are determined by the design of the lens and are fixed. 

A lens is normally quoted has having a focal length or range of focal lengths for a Zoom. Also the smallest F stop for the lens i.e. the larges hole for letting in light. Lenses with a fixed focal length are called Prime lenses. Zoom lenses can have a F stop rating depending on the focal length used. 

An example would be a Canon zoom 28-200mm F2.8-5.6. Which means that at the 28mm focal length the max aperture is F2.8 but at 200mm it drops to F5.6.

A lens’s speed is determine by the smallest aperture it  has. If someone says “How fast is the lens” you would quote say F2.8.  Fast lenses cost more as they are more difficult to produce without distortion.  Fast lenses have a number of advantages which people will pay for. (More later). Leica produce one of the fastest lenses on the market, 50mm F0.95. Current price £5500! ( Even a Digital redundancy payment will not stretch to that. )

Taking a photo at the lowest F Stop i.e. largest aperture is commonly call shooting “wide open”.

Lens Focus and Focal Length:

The simplest to understand. What part of the image do you want to concentrate on. Autofocus was the first to be introduced in the film days. Even the tracking of moving subjects in the frame. The speed of autofocus is critical. Early camera were slow and very frustrating. Today small point and shoots can be very effective. Rampaging grandkids can still be a challenge however! Now reviewers will test autofocus in low light conditions which are the most difficult.

I will discuss focusing in more depth latter in particular in relation to aperture settings.

The focal length of lens determine the field of view that will be framed on the sensor. Longer focal lengths show a smaller area than shorter focal lengths. There are other consequences in choosing a focal length which will be discussed below under Depth Of Field.

Shutter Speed:

Another easier one. How fast will the shutter close. Obvious again - slow means more light on the sensor, fast means less.

Again the number range is “backwards”. Large number are quicker! In older and cheaper cameras shutter lag was a problem. The time from pressing the shutter to the image capture was long enough for a critical moment to be missed. Most camera now are quite fast but worth testing out.

• • • Shutter speeds are quoted in factions of a second. 1 - 10000. Great than 1 sec are usually indicated so you don’t get confused say 10 being a 10th or 10secs. Cameras should have B which means the shutter will be open as long as you have the button depressed.

The settings listed above are all that are required to take a photo which is well exposed and in focus. But there are 2 other actions which are critical to your photo and are not technical related.

What’s in the frame:

This might sound trivial but beware. I’m assuming now you have the ability to move around. With a zoom, framing the photo is helped by just moving the lens in and out. With prime lenses you have to start walking! (See above on Focal Length). Its often easy to concentrate on your subject and diminish other objects in the frame. You need lots of practise to look into a viewfinder and truly see the real final image which will be produced.

In that stunning image of Sydney Opera House from the harbour — is that a blooming great oil tanker just in the edge of frame!! or a crane sticking out of the roof  from the docks further over. Scan round all 4 corners of the frame. Imagine it printed on your living room wall.  Is there too much sky. Is there enough interest in the foregound?  If the sky is plain with no interest I often try and get under a tree to use the branches as a frame. Doesn’t matter that they are too dark or not quite in focus it will be just enough to make the image a bit more interesting if the sky is bland.

Start looking at where is the sun is. What position will show off that Opera House the best.

If you have the time and ability get around. Try to view things from different angles. Bag the simple shot then try for something unique.

Often when travelling there is not the opportunity to spend the time do the things mentioned above and I’ve taken shots knowing they are not the best but that’s the way it goes. Can you get in a position where the “distraction” is limited. Can you crop the image when back home to recover. Done that many times.

When I Press The Shutter:

Again sounds obvious but…..

Midday sun is usually boring, too bright and too high. Morning or evening sun creates more interesting shadows and texture. The sunset is the obvious example but mornings can be even better. 

If I wait a couple of minutes there's a beautiful sailing boat on its way. To produce magic foreground detail in front of the Opera House. If I wait a while will that great rusting tanker move? Again while travelling that may not be possible time being limited.

How The Camera Setting  Are Related

The most important technical thing to understand in photography is the relationship between the setting on a camera: ISO, Aperture - F Stop, Shutter Speed and Focus. Also how they change the look of the image captured.

To say the that life is a compromise is never more true than in photography.

Depth Of Field (Focus):

I’ve mentioned about focusing on the important subject in the frame. But often just about everything in the frame is important. Particularly true in landscapes, your Opera House. On other occasions, portraiture for example, the face is the sole thing of interest and occasionally only the eyes. Everything else you would want to be blurred. 

Software can blur an image but is very limited in sharpening an image that has been poorly taken.

The way photographs expand or limit what is in focus is through the F Stop setting. A lens is focused on an object in the frame. This will be at a distance from the camera. At that point the image will be as sharp as the lens design can allow. Sharpness is not an absolute thing it gets worse either side of the sharpest point. In front and behind it.  How quickly that happens is governed by the F Stop setting. 

Due to the natural laws of optics small F stops (small hole) produce a very slow deterioration in focus either side of the ideal. On my 35mm lens at F11 focusing at 4.5m produces the shortest in focus distance at 2 metres. The furthest focus distance is infinity. Everything from 2m to the horizon will look sharp. If I was taking a panoramic view of Sydney Harbour guess what F stop I would put on my camera ? When walking about taking general scenes in a city or in the countryside I have F11 set with my focus  at 4.5m. I have a point and shoot camera. No need for autofocus. Everything should be in focus from 2 metres to infinity.

If I stop the lens down to F2 and leave the focus distance at 4.5m the shortest distance drops to over 3m and the furthest to below 5m. Objects outside this range will look blurred. The further away from the ideal focus distance the worse it gets. Got any distracting background you want to minimise. Open the lens up as low as possible.

The distance between the nearest focus point and furthest point is called the Depth Of Field.

The Relationship between ISO, Aperture and Shutter Speed:

Lets go back to your acclaimed photo of the Opera House.  We’ll make an assumption that your camera is set at ISO 100. This will make the discussion simpler to demonstrate. Later I’ll remove the constraint. You use the meter in the camera pointed at the Opera House which tells you that to get a perfect exposure of the scene it set the aperture to F16 and the shutter speed to 125th sec. The cameras on auto and the focus has locked on the Opera House. The F Stop is nice and large (small hole), hence big depth of field. A shutter speed is just quick enough to make the photo sharp even though I’m on a rocking boat. Click image in the bag. 

But for a correct exposure that combination is not the only possibility. The camera could have come up with a number of alternatives. You know that the aperture can dictate how much light hits the sensor and so does the shutter speed. Therefore any combination of these that produces the same light intensity on the sensor will produce a well exposed image. So you could open the lens up one stop to F11 but that would over expose the image as its a bigger hole. So to compensate we would have to increase the shutter sheet to 250th sec. For the rocking boat this shutter speed would be a minimum to freeze the scene. For your lens below are the valid combinations. All are great as long as you camera shutter at work at those speeds speed? F22 @60th is definitely too slow a shutter speed on the rocking boat. The Opera House would not be sharp.

This shows the compromise. Large depths of field need slow shutter speeds to get enough light on the sensor. All good landscape photographers take a tripod because they often work at slow shutter speeds too slow to hand hold and get a sharp image.

F Stop	Shutter Speed per sec
F22	60
F16	125
F11	250
F8	500
F5.6	1000
F4	2000
F2.8	4000
F2	8000

Consider now that there are a herd of kangaroos bounding by, going 30mph+. How would that effect you photography. To get a sharp image the shutter speed will have to be quick to freeze the roos in action. No one wants a blurred Roo! Your shutter speed will need to be as high as possibly, 1000th, 2000th. That means that you would be in the F5.6, F4 range.  But that limits the depth of field for a 200mm zoom lens that could be quite shallow and that forces you to be accurate at focusing. Nothing for Nothing in this game.

We can now lift the constraint of the ISO. An increase in ISO will require less light to get a well exposed image. Consider now an ISO of 400. The table would becomes:

F Stop	Shutter Speed per sec
F22	250
F16	500
F11	1000
F8	2000
F5.6	4000
F4	8000
F2.8	16000
F2	32000

All the setting have now moved up 2 stops. F22 is now doable on the boat. But wider F Stops may be out of reach depending on your cameras maximum shutter speed.

So you may be thinking, no problem, I can keep upping the ISO when needed. However the higher the ISO the more noise and distortion creep into the image. This depends on the quality of the sensor in the camera.  In the photos I took at Fiona’s most are at ISO 3200. That’s about the limit of my Leica. My Fuji can go to 6400 for the same results. 

A Word About Exposure Measurement:

I scooted over the camera metering above. This also has various alternatives. But first lets consider a correctly exposed image with a well balanced exposure but what does that mean.

What is a Well Exposed Image:

Most imaging software will show the image pixels and give values for the Red, Green, Blue components or RGB values. My software (Adobe Lightroom) has values between 0 and 100 for each component. A perfect grey is were the RGB values are all the same.  In particular a pure white is 100, 100, 100 and a pure black is 0,0,0. A pure white means that the sensor has been flooded and maxed out. A pure black means there is no light effecting the sensor. In an ideal image both these extremes are not present. If any important part of your photo has 0,0,0 then you have an under exposed the image. If there is 100, 100, 100 you have an over exposed the image. The question is how to you determine that at the time you take the image.

Cameras will often show a histogram of the pixels showing the number of pixels from 0 to 100. If the histogram is biased to the left with few pixel counts on the right then the image will be generally underexposed. If the histogram is biased to the right its over exposed. You want a nice hill with a nothing to the left or the right. Alternatively after the shutter has fired many cameras in the image review can show any pixels which are blocked out or bleached out by using flashing colours. This will allow adjustment and a re-take.

How to Measure the Scene:

Cameras will often offer various ways of measuring exposure which usually change the number and position of pixels sampled. The usual ways are Matrix, Centre Weighted or Spot Metering. 

Matrix Metering tries to review a larger area of the image to help understand the white or black spots and comes up with a balanced exposure which ensures that nothing is outside the sensor range.

Centre Weighted Metering usually an oval of pixels around the image centre. My Leica has this and I understand how to use it.

Spot Metering: This uses a small area in the centre of the image. This is the best way to work with complex images which are high contrast. You can move the camera around sampling parts of the image to understand the exposure. Half pressing the shutter will engage the meter.

Once an exposure has been measured many cameras can lock the setting until you are ready to take the image.

What the Metering Will Produce:

The camera meter will assume its looking at a general scene pretty much like your Opera House scene. However we may frequently want to photo scenes which are not so general.

The classic is the wedding scene with very white bridle gown and a very dark grooms suit. Meter the dress and it will come out grey and the suit will be blocked out black. Meter off the suit and the reverse will happen. The dress will bleach out missing all that nice stitching and the suit will look grey. The other problem is snow scenes. Without adjustment the snow will be grey. The wedding problem is solved by metering off the dress and over exposing my 2 stops. If the suit blocks out, tough, the dress is the important subject. Snow is the same manual over expose by 2 stops. These corrections are usually done by the exposure compensation setting.

Colour Balance:

This is often the most difficult to understand. This is because your brain is way better at dealing with colour correction than a camera. You have done it all your life without realised it. 

Artificial light is the most problematic. Old type strip lighting will cause a green case on an image. Tungsten light produces a red cast. Your eyes see these colours but your brain corrects it. The camera was white (colour) balance settings. All my cameras have an auto setting that is usually pretty good but can get confused in light that is mixed, containing artificial and natural light.

Good imaging software will allow measurement and correct over and above that done in the camera. In Adobe Lightroom I can sample a point of the image which is a pure grey, RGB values equal. This weekend I used the white part of Annette’s dress. The software will then automatically correct all the colour in the image.

Occasionally a colour cast is not corrected. A sunset is the prime example. The red glow is never corrected to look like noon!!!!

Summary

What setting on the camera should be used is a question of what your vision of the final image is.  You have to decide what is important and what compromises must be made if any. What criteria is driving you. High quality, freeze fast action, deep depth of field, a moody under exposed image or a bright high key photo with muted colours may all be possible. 

The above are the basics with these you can use for any camera. All you may have to do is plough through the manual to find out how the settings are changed!!!

What Comes Next

The Skill of Using the Camera:

The description above lists the technical choices which are available to a photographer. 

A camera is a tool and a photographer, as second nature, should know how to use it to obtain their vision of the scene. This can only be achieved by practice and taking 'a lot' of photos! 

Therefore before going on the trip of a live time spend as much times as possible taking photos in many different situations. Learn the limitations of your camera.  

Taking a "Good" Photograph:

The definition of a "good" photograph is a subjective measurement. There is no right or wrong answer. Certainly my photographic likes and dislikes have changed over the years. 

There are a number of basic rules which are often quoted. 

No Part of the Photo Should Be Over/Under Exposed: Every part of the image has  detail.

The Rule of 3rd - Some cameras can show a grid over a scene where width and height are divided into 3. Putting your main subject on one of the 4  points of intersection of the two lines is considered to be a balanced composition.  Most people tend to this say that looks "right". 

Guiding the Eye: - Use elements of a scene to lead the viewers eye to the main subject. This can be fences, roads, rivers, buildings or other people in a scene.  Is your main subject looking into the body of the image.

Has the Photo a Fore, Middle and Background:  Are all parts of the image relevant and balanced.

Tell the Story: -  Does the photo ask the view to think what happened before of what might happens next. 

Breaking the Rules: - Ignoring the above also has its place!!!

The Camera as a Sketch Book: - Don't expect to take only one photo of a scene. I normally expect to keep about 20% of the photo I take. Experimenting with angles, camera setting and timings is normal. 20% may be liberal and good images may be much lower!!!  

Editing Your Images: - If you take 800 images on a holiday perhaps 50 to 100 are worth sharing with others. Being critical of your images is an important skill.