Tag Archives: aperture

DIY Photography Course

December 2, 2014 Passy Leave a comment

Welcome to our Free Online Digital Photography Course!

Music and Photography are my passions.

Teaching Mathematics, Photography, MultiMedia, and ICT is my “Day Job”, but I manage to get out and about most weekends working as a Photographer.

Modern Digital Photography actually involves quite a bit of behind the scenes Mathematics.

An understanding of this Mathematics can definitely make you a better Photographer, even if it just means you know the best Viewpoints, Angles, and Geometric Composition to use when taking pictures with a Mobile Phone.

I have found that understanding the Mathematics of a DSLR Camera really helps me do fast effective problem solving on Photoshoots.

But don’t let a bit of simple mathematics put you off doing Digital Photography. There are lots of proactical examples and explanations to get you through.

Digital Cameras have preset Auto Modes which work well in about 80% of situations, but there are other times when a Camera needs to be put into full Manual Mode and some Mathematical Problem Solving invoked.

Here at Photos By Passy we have produced a comprehensive series of articles on Digital Photography, including plenty of real life examples as well as selected Videos which can be viewed.

We recommend working through these articles in the order in which they appear in the Overview Below.

The eight Digital Photography articles are as follows:

– Photo Composition Rules

– Digital Camera Settings

– ISO Light Sensitivity

– Aperture Settings

– Shutter Speed Settings

– White Balance Settings

– Combining Settings for Correct Exposure

– Flash Photograpy and Diffusers

Contained below is an outline of each article followed by a clickable link to the full article.

It is important to work through the articles in the order they are given here.

Like great Works of Art, the elements in a Photograph need to be arranged in a manner which is interesting and pleasing to the eye.

In addition, Photography is a two dimensional medium. Therefore we need to make use of the elements which are present in the photo to create a sense of depth and three dimensions.

Photos also need a main focal point, as well as leading our eyes on a journey through the picture.

Having these things makes for great photos, which are pleasing to the eye, and we call this “Composition”.

There are a Number of Composition Rules involving Percentage, Geometry, Symmetry, a Grid of Thirds, and even the “Golden Ratio” and its spiral.

To find out about these rules and their Mathematics, click the link below:

Photo Composition Rules

Most people use their camera on “Auto” mode, and get plenty of good pictures.

However, there are many items on a camera which can be adjusted manually to get even better pictures!

In this “How To” article we introduce several of these camera settings, and show how they can be used to create quality photos.

An overview of the three main Variables: “ISO Light Sensitivity”, “Aperture”, and “Shutter Speed” is provided.

This provides the preliminary background to more detailed articles on each of these three key items.

It is therefore vitally important to read this article before proceeding forward to the specific detailed articles.

To read the Introductory Article about Camera Settings, click the link below.

Digital Camera Settings

ISO sets a Camera’s sensitivity to light

Effectively it works like a Brightness Control on your camera, and you can turn it up higher if you are in a dark room, or in a shady forest.

If you are in Bright Sunlight, then you need to turn the ISO down to a low value or else your photo will come out all white and washed out with too much brightness.

Camera ISO is one of the three key Variables of Photography, the other two being Aperture and Shutter Speed.

Every photographer needs to understand ISO in order to get bright and clear pictures from their equipment.

The ISO sequence is: 100, 200, 400, 800, 1600, 3200, 6400 and etc. For every step up in this scale, the brightness of your picture doubles.

To get the full story on ISO and how to set it correctly on Digital Cameras for a variety of lighting conditions, click the link below.

How to Do ISO

Aperture is one of the key variables in Digital Photography. The other two are ISO Light Sensitivity and Shutter Speed.

An understanding of Aperture is critically important to isolate subjects in portraits and get full detail in Landscape pictures.

The Aperture Scale consists of a seemingly odd set of decimal and whole numbers, and getting your head around these values is not at all easy for Beginner Photographers.

In this article we examine Aperture in detail, and mathematically explain where the Aperture “f-numbers” come from.

Click the following link to read the full article.

How To Do Aperture

Shutter Speed is mainly used for creating dramatic effects by either freezing action or blurring motion.

The Speed is expressed in a fraction of a second, and is how long we let light in through the camera lens to the sensor.

Think of the Shutter as like opening and closing a set of venetian blinds quickly to let a burst of light into a darkened room.

Shutter Speed, (also called “Exposure Time”), becomes critically important in situations outside of the norm, such as the following:

1) Fast Moving Sports Action

2) Dimly lit indoor areas such as Bars and Clubs

3) Night Time Photography

4) Theatre and Musical Performances

5) Indoor Photos using Flash

6) Indoors Photos where we do not use Flash

7) Photos where we want motion blur for fast moving objects

8) Bird and Wildlife Photography

9) Photographing Young Children and Animals

In this article we will show you what Shutter Speed is, what the speed numbers mean, and how to set shutter speeds to values which should produce great photos.

Click the following link to read our article on Shutter Speed.

How To Do Shutter Speed

Different light sources produce light with slightly different colour tints, but our eyes do a great job correcting these variations.

Humans do not see a shift in colour as we move from a sunny garden into a shaded area, or go into a room and turn a light on.

Generally wherever we are, a piece of plain white paper always looks white.

However Digital Cameras DO detect light source differences, and sometimes create pictures with incorrect looking colours in them.

We need to know how to perform “white balance” adjustments, so that we can obtain pictures with realistic colours in them.

White Balance involves the Primary Colours of the Spectrum forming a Kelvin Temperature Scale from “cool” blue/violet through to warm “red” candle light.

What we have is a Mathematical Scale of color, and White Balance blends various colours together so that a white sheet of paper will look white, no matter what coloured lighting we are in.

You can read the full article on White Balance at the following link:

How To Do White Balance

In this article we look at Combining Variables for Correct “Exposure”.

We tie together the three key Digital Camera Variables: ISO, Shutter Speed, and Aperture, and discuss how to set these up to get good exposures in Camera Manual Mode.

When these three variables are optimised and unified together, we get a nice clear picture with great contrast and highlights. We say that the photo is correctly “Exposed”.

You can read the full article on Getting Correct Exposure Using Key Variables at the following link:

Combining Variables for Correct Exposure

In this article we discuss Flash Photography and how to use Light Diffusers to make Flash Photos look so much better.

Diffusers come in all types of Geometric Shapes and Sizes and create softened light which is more like Daylight.

The Intensity of Light from a point source like an on camera Flash follows an Inverse Square Law with the Distance the Flash is from the subject.

This is very important to have an intuitive idea about Inverse Square Law when changing the Power on a Flash, or when we move further away from the subject being photographed.

The full article about Flash and Diffusers can be read at the following link:

Flash Photograpy and Diffusers

Working through this series of articles will definitely make you a better photographer.

Keep in mind that I spent a couple of years working with Digital Photography to reach this level of understanding to a point where I could write about it to share my knowledge with others.

So if you are a complete beginner and feel a bit overwhelmed, then that is okay, these things just take practice and time.

It is best to work through all of our eight articles a bit at a time, try things out, and then come back to the articles to pick up a bit more of the finer detail.

The Maths is helpful, but the main thing about being a Photographer is to get out there taking lots of pictures!

Life is short and there can never be too many photos of its little magic moments!

Enjoy,
Passy

How To

How To Do Exposure

November 23, 2014 Passy Leave a comment

In this article we look at “Exposure”. We also tie together the three key Digital Camera Variables: ISO, Shutter Speed, and Aperture, and discuss how to set these up to get good exposures in Camera Manual Mode.

When these three variables are optimised and unified together, we get a nice clear picture with great contrast and highlights. We say that the photo is correctly “Exposed”.

It is essential that you have been through the following previous articles, before reading through this “How To Do Exposure” article.

Here are the links to this essential background reading:

How To Do Camera Settings

How To Do ISO Settings

How To Do Aperture Settings

How To Do Shutter Speed

Let’s start off by quickly going through the definitions of “Exposure”, “Underexposure”, and “Overexposure”.

Underexposure in Photographs

Underexposure results in a dark and dull image because too little light was recorded by the digital sensor.

Underexposure often makes an image too dark for subjects to be seen clearly.

The amount of underexposure will determine how dark a photo is.

Overexposure in Photographs

Overexposure refers to a white-looking or washed-out image.

This is caused by having too much light reaching the digital sensor which makes the photo come out way too bright.

Correct Exposure

When we have correct exposure the tone in the image will range from white all the way though to black.

The picture will also contains all the tones in between black and white, resulting in crisp bright clear image.

Eg. We have a contrast in our image with a little dark and a little light, as well as a lot of inbetween.

The example photos shown here are photos of “Simmeau” from the fabulous Australian Led Zeppelin tribute band: “Shed Zeppelin”.

For more information about Shed Zeppelin, check out their Facebook Page here:

Shed Zeppelin Band Facebook Page

Camera Exposure

The camera uses an exposure meter which looks at shades of grey in the photo to mathematically get the correct exposure or tonal range.

(Basically Cameras see in Black and White, rather than in colour).

The light meter and processor decide what ISO, Shutter, and Aperture to use when the camera is in Auto Mode.

When we have bright rapidly changing indoor lighting, the camera has issues. It might expose for bright light, making the rest of the photo way too dark and underexposed.

We are often better off changing to manual mode and setting the camera variables manually ourselves.

There are some great videos all about Camera Light Metering in the Videos section near the end of this article.

Watching these Metering Videos will help you understand how cameras determine exposures, and what mistakes the camera can make when doing this under certain lighting situations.

Video About Exposure and Variables

The following is an excellent fifteen minute video about the Mathematics of Exposure.

Watch this video all the way though before reading the rest of this article.

Camera Variables and Exposure

Sometimes the camera’s auto mode metering does not give us the exposure we want.

Auto Modes usually work well outdoors in bright sunlight, when the sun is behind the camera.

But if it is overcast, or we move into the shade, or we are facing into the sun, or we go indoors, the exposure can often be Overexposed or Underexposed, and far from ideal.

In cases like this we need to shift our camera into Manual Mode, and Adjust some, or all, of the three key variables.

Manual Mode is basically a mathematical problem solving exercise, and it can be tricky to get all three variables at their optimum values.

When we get ISO, Aperture, and Shutter Speed all at just the right settings, we can get a really well exposed photo in full Manual Mode.

Sometimes we may have to adjust a fourth variable of “White Balance” as well; eg. Change over to incandescent lighting if we are taking a photo indoors at night time.

We need to know the effects of changing each of the variables: ISO, Aperture, and Shutter Speed.

Exposure is all about getting the right amount of light to reach the sensor, and so we often need to adjust the variable settings to get more or less light coming through.

For example, if we shoot a picture and which is too dark and underexposed, then we need more light.

However, if we shoot a picture which is too bright and washed out, we need to change things so that less light comes to the sensor.

The following “Table of Full Stops” needs to be understood, so that we can make the necessary changes in the amount of light in a mathematical manner, and not just be randomly guessing at what might work.

Limiting Factors

The additional complication is that each Variable has some limiting factors:

– ISO cannot be set too high in low light, because we may get ugly “noise” fuzzy dots all over the photo

– Shutter Speed cannot be set too slow in low light, because we will get blurring of moving objects, and/or camera shake blurring

– Aperture cannot be set too open at f2.8, or people slightly in the background may become out of focus.

Aperture determines how much of a photo is clearly in focus.

Often we are forced to use f2.8 when taking band photos, just to get enough light for a good exposure. However this makes people and items in the background out of focus, but this is often not such a bad thing.

When taking a Group Photo, it is important that everyone in the picture is in focus, even though some people are nearby and others are far away. In this situation we need to use an Aperture of f4.0 to f5.6 so that we have enough depth to capture everybody clearly.

It is therefore a delicate operation to find the settings for each of these variables so that they will all work in unison to create a well exposed photo.

Scene Mode Exposure

For certain situations, we do not need to change to full Manual Mode to get good quality pictures.

Modern Digital Cameras have Preset “Scene” Modes which can be used for situations such as : Outdoor Portraits, Landscape, Sunsets, Action Sports, and several other common environments.

These Scene Modes, with their Preset values of ISO, Aperture, and Shutter Speed work extremely well, as long as the lighting conditions are what is typical for that particular Scene Mode.

Some typical Scene Modes, and their limitations are discussed in the next two sections.

Preset Scene Modes on Cameras

Modern Digital Cameras have one or more fully “Automatic” modes, as well as special preset or “Scene” modes.

These generally do a great job of setting up the Aperture, Speed, and ISO variable values for us.

All we have to do is “shoot” or “snap” the picture, and the results look fantastic.

For example, if we set our camera to “Portrait” and take a picture of a person outdoors, it will turn out nicely with “bokei” (Background Blurring).

The Birthday Party pictures shown above were all taken using daylight portrait mode, which set our variables well, and also softened skin tones to make nice looking people photos.

However, if we set our camera to “Landscape”, the camera will make a nice bright picture where things both near and far from us are all in detailed focus.

Here is a great three minute video all about using Preset “Scene” Modes.

Auto and Scene Mode Limitations

Problems arise when we venture outside of normal daylight conditions, and attempt taking indoor shots without Flash, or we take portrait or party pictures with flash.

These “low light” and “Flash” photos often do not turn out as nicely as we would like them to.

We can Photoshop some of these pictures to improve them, but it is very time consuming.

It is better and faster to get good shots straight out of the camera by using Full Manual Mode, which will be discussed shortly.

Special areas of difficulty are photographing Rock Bands, Indoor Sports events, and Night Clubs, where there is not full daylight, and people are moving around.

On some Sony cameras, using “Sports” mode will sometimes produce reasonable shots in these conditions, and Canon cameras have a “Television” mode which sometimes works.

However, the best results for “low light” photography can be obtained by setting your camera to full “Manual” mode, and adjusting the variables yourself – fast enough shutter speeds to freeze action, wide open apertures to let as much light in as possible, and high ISO sensitivity so the camera sensor will work like “night vision” to pick up as much light as possible.

Manual Mode Exposure

Using Full Manual mode “M” is a matter of trial and error, combined with experience, and thoroughly getting to know your camera.

For example, for my Sony A77 camera, I know from experience that I cannot put the ISO higher than 1600 or there ugly noise dots and graininess begin to appear.

Even at ISO 1600 there can sometimes be a small amount of noise on the A77.

So rather than use ISO 1600 as a default for low light, I always check to see if I can slow down shutter speed, and use f2.8 Aperture, which might then allow me to shoot at ISO 1250 or ISO 800 which then gives negligible noise.

For Aperture, I know that if I am doing a Group Photo with some people further back or behind others, I have to use F4.0 to f5.6, or else the further away people will be out of focus.

For Shutter Speed, I know from experience that when photographing people or rock bands, that the minimum shutter speed for no blurring is 1/100. I have also discovered that the minimum shutter speed for action sports photos is 1/250 but it is much better to use 1/1000 if possible,

The point is that an experienced photographer is not blindly setting some variable and hoping for the best.

What they usually do is set one of the variables at a particular value, and then manipulate the other two to get the best exposure.

This is done by taking test shots, seeing what they look like, and then progressively making smaller and smaller adjustments until the resulting image looks good.

From my experience of taking lots of photos, I usually have an idea of what the approximate settings are for a given lighting situation, and then work on fine tuning these values to get the best possible exposure for the particular camera I am using – Sony A77, Sony A55, or Panasonic Lumix LX-7.

I know when I first started using Manual I had no idea of what to set things at, and I was totally frustrated.

So if this is your first experience when using Manual Mode do not be concerned. The path to mastery of exposure is usually not an easy one.

It is important not to give up, because being able to shoot in manual gets great photos in low light situations that people in Auto Mode will never be able to match.

Think of all those whited out Flash shots people take at parties, or those blurry noisey dark photos without the Flash.

Manual Mode is well worth learning so that you can be the person who gets the “Wow” factor photos, while others are floundering.

As I said, when I first tried Manual Mode I was totally lost as to how to begin to change the variable settings.

What I found though was that if I set the camera on auto and looked at the live view to see what settings the camera was choosing, I could then flick to manual and use these variable settings as my starting point.

There is only one way to master variables, and that is by going out and shooting a lot of photos and trying out different settings until you know the ones which give good results for your camera.

It is time consuming and frustrating at times, but it is well worth the effort in the end, when you have the great photos that nobody else can get!

What follows are some Exposure Settings examples. Read through these, and then watch all of the videos in the video section.

This will help you start getting your head around Manual Mode, and show you what effect changing each of the three variables has on the final photo.

After that it is all down to getting out and shooting lots of photos in Manual Mode and seeing the results. Then one day it should suddenly all start to “click”, and you will be able to problem solve exposure settings for difficult shooting conditions such as low light indoors without the use of flash.

Good Luck! It is a difficult path, but one well worth travelling.

Exposure Settings Examples

“A picture is worth a thousand words” so let’s take a look at some examples of variable adjustments made in Manual Mode.

Our first example below involves ISO light sensitivity.

In this second ISO example, the original settings produced an overexposed picture.

We did not want to change the Aperture, and could have increased shutter speed or lowered the ISO.

The shutter speed was already fast enough to freeze the action, and so it was better to lower the ISO to get a clearer more detailed image.

Generally, if the shutter speed is freezing the action well on an Overexposure, leave it as it is, and Reduce the ISO.

Our third example involves Shutter Speed for Indoor Sports.

As discussed in our “Shutter Speed” article, using the Auto “Sports Scene” mode on digital cameras works great outdoors in bright sunlight, but often has severe limitations for Indoor Sports.

Note that we cannot shoot Sports Action without motion blurring at speeds less than 1/250, and we should aim to use speeds of 1/500, 1/1000, or even 1/2000 if possible.

Another example of Shutter Speed involves Motion Blurring.

In the first photo below, we had a low shutter speed of 1/80 which gave plenty of light, but resulted in blurring of the singer’s moving hands. This blurring is a bit difficult to see in the small sized photo below, but it is there and it did make the photo unusable.

Moving to a higher speed of 1/125 stopped the blurring, but did create a darker picture. Sometimes we are faced with these types of compromises, and it is impossible for the camera we are using to get the penultimate perfect exposure. That’s Life – we can only strive to achieve perfection as much as humanly possible, and there are always some ultimate limitations.

Our final example is another one involving Aperture.

The original image was underexposed, and we could have increased the ISO up one stop from 800 to 1600, (and get twice as much light), but this might have also introduced a small amount of graininess.

We therefore made an Aperture adjustment instead, and were able to get 2 times more light by going down to the wider f2.8 value, which made some background blurring, but gave us sufficent light correct exposure.

By moving from f4 to f2.8 we changed the Aperture by “one full stop”.

Videos About Exposure

The following video is useful for Canon and Nikon Camera users and shows how to change the ISO, Aperture, and Shutter Speed settings.

The presenter goes through where all the dials and buttons are on the camera are to do this.

Watching this video made me realise how much easier my Sony A77 is to use, where I have a wheel on the front grip, and a wheel on the back to do this.

Here are some excellent videos about Aperture and Shutter Speed on Sony Alpha Cameras.

Sony Aperture Video

Sony Shutter Speed Video

This next fifteen minute video is about the effects the variable settings have on photos and gives plenty of practical examples.

It is essential viewing for learning about how to use your camera in Manual Mode, and get great exposure.

Here is Part 2 of the above video:

Here is a 10 minute Video about the three key variables: ISO, Shutter Speed, and Aperture.

The effects and side effects of altering these variables is also discussed.

The following is a fifteen minute video with practical examples which shows how to adjust camera variables for various lighting conditions.

Here are is a video lesson in two parts from NightClub Photography TV about setting camera variables.

And here is Part 2 of the above video.

In this next video the guy talks for 23 minutes about all of the variables and how they work.

It is worth watching after the other videos, but does not contain any practical examples.

Videos About Metering and Exposure

Cameras have Metering Modes for fine tuning the light reading. Here is a good five minute video about these Metering Modes.

This next twenty minute video is an excellent explanation of camera light metering with practical examples.

How To Do Aperture

September 18, 2014 Passy Leave a comment

Aperture is one of the key variables in Digital Photography. The other two are ISO Light Sensitivity and Shutter Speed.

It is a good idea to read our previous article on “How To Do Camera Settings” before working through this Aperture Article.

You can access this article at the following link:

How To Do Camera Settings

An understanding of Aperture is critically important to isolate subjects in portraits and get full detail in Landscape pictures.

The Aperture Scale consists of a seemingly odd set of decimal and whole numbers, and getting your head around these values is not at all easy for Beginner Photographers.

In this article we examine Aperture in detail, and mathematically explain where the Aperture “f-numbers” come from. The mathematics might be challenging for some people, but do not worry too much about the detail if it is challenging for you.

The main thing we need to understand as Photographers is how the “f-stop” number values relate to the amount of light made available for our image, and how the background can be deliberately blurred using Aperture settings.

Definition of Aperture

Camera Aperture basically imitates the function of the human eye.

In dark conditions we require more light entering our eyes and camera, but in bright light we need far less light.

Our eyes adjust to these conditions using our “pupils”, (the central dark circles inside our eyes).

A camera mimics the action of our pupils using a setup that creates various size circles; and we call this camera function “Aperture”.

Using Camera Aperture Values

We go to detail about this later in this article, but just as a starter, here are a couple of examples where we use different sized Apertures, which mimic the function of the human eye.

Lens Aperture Values

The Aperture function is performed in the Lens of the camera, and not in the Digital Camera Body. (The “Lens” is the cylindrical barrel on the front of the camera, and the “Body” is the back part of the camera with all the buttons and dials on it.

Each lens we mount onto a DSLR camera has its own Aperture System, and as we will see later on, different sized lenses need to have their own particular Aperture systems.

Lens Apertures are specified using f Numbers which are called “f-stops”.

These numbers make little sense at all when we first look at them, as they are what seems to be some weird random collection of decimal and whole number values.

A first look at these strange f-numbers reveals that there are doubling patterns in the list of numbers from f1.4 to f22.

Another very confusing aspect of these f-numbers is that as they go up in value, the size of the circular Aperture openings actually goes down in value, and the cicular “Aperture” openings become progressively smaller.

In fact each circle becomes exactly half the size of the one before it.

This is indeed very confusing, as the smallest number 1.4 represents a large fully open camera lens letting in lots of light, but the largest number at f22 represents a tiny cicular opening in the lens which is not letting much light in.

Mathematical Patterns

The standard f-numbers are: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22 .

We can always form the next number in the pattern by multiplying by 1.4, which is the square root of 2 as a rounded off decimal value.

1.4 x 1.4 = 1.96 = 2

2 x 1.4 = 2.8

2.8 x 1.4 = 3.92 = 4

4 x 1.4 = 5.6

5.6 x 1.4 = 7.84 = 8

and so on.

In the f-numbers we have a sequence of numbers, where we always multiply by a common value of 1.4 to generate the next number.

In mathematics this is called a “Geometric Sequence” or a “Geometric Progression”

The common multiplying value, in this case 1.4, is called the “Geometric Ratio”.

The 1.4 (Square Root of 2) value results because we are dealing with Circles when we are doing Apertures.

If we want to make a Circle twice as big, it turns out that we need to increase its Radius by a factor of Square Root of 2, which in decimal is 1.4.

So if you are wondering where the 1.4 multiplying factor comes from, it is all due to the way the area of circles is doubled.

The f-numbers sequence is set up so that in real terms the amount of light due to the circular opening halves as we move up through the f-numbers.

F-Stop Formula

We are nearly through the Mathematics of Aperture.

As a Photographer you do not need to memorise all this mathematics, you simply need to understand the consequences in relation to light entering your camera.

There is a Mathematical Formula for f-stop which relates the 1.4,2,2.8,4,5.6, etc values to the actual Aperture Circle Diameter, and the size of the Lens you are using.

Aperture is not just related to how wide we make our circular opening, (the “Diameter”), but it is also related to the size of the Lens we are using which is specified as the Lens “Focal Length”.

We will confine our discussion to fixed size lenses, called “Prime Lenses”, and talk about “Zoom” lenses later on.

A 28mm Lens is a short lens, which gives a very wide angle of viewing.

A 50mm or 55mm lens is a standard size which is supposed to be a lot like the angle of viewing, or field of vision that is in focus when we are looking at something with human eyes.

A 200mm lens is a “Telephoto” type lens which will make distant objects look a lot closer, just like a set of Binoculars would.

The 28mm lens with its wide view lets in the most light, and the 200mm long lens lets in the least light.

Thinks of it like being at the Beach.

If you were at the beach looking at the whole scene there would be lots of light from the sun, and its reflection on the water. This is what a 28mm lens gives you, a nice wide picture where you can see everything, and there is plenty of light.

If you were just looking at some children building a sand castle, then this is the type of view from a 50mm lens.

If you were using a 200mm lens to look at some guys fishing in a boat off the shore, then this is a zoomed in type situation, and you only get the light from the boat and people, and not lots of light like when you are looking at the whole beach scene.

This is the reason why we need to take “Focal Length” or lens size into account. To get the same f-stop amount of light, we actually need different sized circular openings on different sized lenses.

In the example shown below, the two lenses are set to the exact same f-stop, so that the exact same amount of light can reach the interanl camera sensor.

However, to get the exact same amount of light into the camera body, we need to use a much larger physical Aperture opening on the long 200mm lens.

Video About Aperture

By now you might be totally overwhelmed by all of this Mathematics, but do not worry about it, because the main thing you need to understand is that Aperture changes the circular lens opening to let in more light or less light.

If we adjust our current F-Number UP to the next F-Number we HALVE the light.

If we adjust our F-Number DOWN to the previous F-Number we DOUBLE the light.

We need to adjust the light to get a picture that is not overly bright and washed out, and not overly dim and too dark to see its contents.

The following 15 minute video explains what we have covered so far.

Some Final Mathematics

Here is one last set of Mathematical calculations to show how Aperture works for different sized lenses.

We will work backwards to find the actual mm diameters of the circlular openings we would need in two different lenses to get the same amount of light which would mean we had the same f-number or “f-stop” set on each of the lenses.

To find the Diameters required, we rearrange our previous f-stop formula as follows:

Once we have the diameter required, we can halve it to get the circle radius and then calculate the actual Area of the circular opening we would need in the lens to create given f-stop amounts of light.

These calculations are shown below:

The above calculations were obtained from an excellent article on Camera Mathematics from Mr Martin which can be viewed in full at the following link:

Mr Martin Mathematics of Photography Article

By examinng the results of the above calculations we can see the following patterns and results:

One Third F-Stops

Finally just to add another layer of complexity to everything, if you check the Aperture f-number values on your actual camera, it is likely that there will be more than just the standard values we have been discussing:

1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22

Your camera (thanks to the wonders of modern technology) will have the standard values, plus a whole lot of extra in between values.

These values allow you to change your Aperture light up or down by 1/3. This way you can open the Aperture up to 1 and 1/3, then to 1 and 2/3, and then up to Double the amount of light.

Your camera will possibly have this full set of one third f-stops, resulting in a sequence like this:

1.4, 1.6, 1.8, 2, 2.2, 2.5, 2.8, 3.2, 3.5, 4, 4.5, 5.0, 5.6, 6.3, 7.1, 8, 9, 10, 11, 13, 14, 16, 18, 20, 22

Aperture Blades

Anyone who has ever tried to draw a perfect circle freehand knows exactly how hard it is to do.

It is also very difficult to mechanically make circles of different sizes, and often the Aperture openings are not actually circular, but might be Pentagons, octagons, or other multisided geometries.

The lens uses a series of adjustable “Aperture Blades” to make the best circles it can.

Basicially the more you pay, the more blades in the system, and the better the circles will be.

Two lenses sitting side by side might have drastically different prices, because one of them has a many blades quality system inside it.

If you have a cheap lens with not many blades, blurred lights in the background will not be round, and you may also get some slightly dark tinges in the four corners of your photos.

Aperture and Zoom Lenses

Most people have an adjustable zoom lens on their camera, which can do wide angle shots, through to zoomed in telephoto pictures.

As we saw previously, the field of vision narrows as we increase lens focal length, and so it is tricky for the Aperture system to continually adjust to different focal lengths as you zoom in and out.

This is why there are cheap and very expensive zoom lenses.

A Cheap Zoom Lens for $300 might only allow Apertures from f4 to f8 and the picture will darken as you zoom in.

An expensive f2.8 Zoom for $1500 to $15000 will allow you to use all Apertures no matter how far you are zoomed in or out.

Those giant white “bazooka” looking lenses you see at sports events can cost anywhere from $5000 to $25000 !

Aperture and Blurring

Well that is all the Mathematics and Technical stuff done with, and now we can talk about actually taking some photos!

A really nice side effect of using wide open Apertures is that we end up with our subject at the front of the picture crisply in focus, and the background we are not interested in all blurred out for us.

However, if we want to see our whole photo in clear focus, like on a landscape shot, we need to do the opposite and set a very narrow (high f-number) Aperture.

Group Shots and Blurring

However, with taking “Group Shots” of people we run into a problem.

If we use f1.4, or f2, or f2.8 to get nice background blurring, we will find that people in the back row of the group will be blurred out of focus.

To get the whole group in focus we typically need to use an Aperture of f4 or f5.6, which will make sure everybody in the group is in focus.

However, the background we are not interested in will also be in focus and clearly visible.

The way aorund this problem is to use Blurring Tools in Photoshop, as has been done below.

Aperture and Sunsets

Sunset Photos can also be interesting for setting up the Aperture correctly.

We might use a really narrow Aperture like for a landscape, and our image will be too dark; or we might use a wide open Aperture and have our photos turn out too bright and look like daylight.

The best Aperture to use is between f8 and f11, as shown below in these great photos taken by our friend Nicole Cooper.

The following page has thirty great tips for taking good sunset photos:

30 Tips for Taking Sunset Photos

Video About Aperture and People Shots

Finally here is a two part video totalling around 25 minutes all about how to set your Aperture when doing Night Club Photography, or really any Photos at Events like Birthdays, Baptisms, Parties, and so on.

Here Part 2 of the above Video.

Sony Video About Aperture

Here is an excellent video all about Setting Aperture on Sony Alpha Cameras.

References

Click the following links for more articles on the web about Aperture.

Digital Camera Mathematics

Very Technical Maths Explanation of Aperture

Mathematics of Aperture

How Aperture Blades Work

Mathematical Explanation of F-Stops

Using Camera Settings

August 1, 2014 Passy Leave a comment

Most people use their camera on “Auto” mode, and get plenty of good pictures.

However, there are many items on a camera which can be adjusted manually to get even better pictures!

In this “How To” article we introduce several of these camera settings, and show how they can be used to create quality photos.

Camera Variables

A “Variable” is something which we can change the value of to different numerical settings.

Eg. The Temperature Setting on an Air Conditioner, the Volume on a Music Player, or the Brightness on a Mobile Phone.

On Digital Cameras there are several items (or “Variables”) which we can change the value of before clicking the button which takes the photo.

In this “How To” Guide we provide an introduction and overview about these Digital Camera Variables.

Separate detailed “How To” Guides, (which are not part of this particular article), examine each of these variables in detail.

The Guide on “How to Do Exposure” is all about how we combine all the Variables to get the best possible photo for a given set of lighting and subject matter conditions.

See the “Related Items” section at the end of this article for links to these detailed “How To” Guides.

Digital Camera Variables

In Digital Photography, there are three key variables:

“Aperture”, “Shutter Speed”, and “ISO”

Getting the right combination of these three variables is how we can capture a moment in the form of a great photograph.

When we take a shot with a Camera:

– Aperture is how wide the “tunnel” or “hole” leading from the lens to the sensor is set at

– Shutter Speed is how quickly the inside of the camera opens and closes to let light through to the sensor

– ISO is the sensitivity to light that the pixel sensor is set to.

Aperture

Aperture affects how much light enters the camera, and creates blurred backgrounds for Portraits and full details for Landscapes.

For Portraits we set a wide open Aperture to let in plenty of light, and this also blurs the background. This makes attention focussed on the person.

For Landscape shots we want the foreground as well as everything in the background to all be in focus. Using a small narrow Aperture makes this happen.

There is a detailed “How To” article on Aperture at the following link:

How To Do Aperture Settings

Shutter Speed

Shutter Speed needs to be set to a fast value to capture wildlife or sports action, but needs to be set very slow to let enough light in for sunsets or night scenes.

There is a detailed “How To” article on Shutter Speed at the following link:

How To Do Shutter Speed

ISO Light Sensitivity

For ISO Light Sensitivity – In bright daylight, the sensitivity or “ISO” can be at a low value.

Eg. In daylight conditions there is plenty of light coming through the camera lens to the sensor, and so the sensor does not need to be made to catch any extra light.

However for sunsets, shade, indoor, and night scenes, the light sensitivity ISO needs to be increased; otherwise we get a very dark picture with no detail.

There is also the low light solution of using a Flash to provide the equivalent of Daylight; however sometimes indoor scenes, especially those capturing musical or theater performers, look a lot more natural without Flash.

There is a detailed “How To” article on ISO Light Sensitivity at the following link:

How To Do ISO Settings

White Balance and Colour Temperature

There is a Fourth Variable associated with Digital Photography known as “White Balance Colour Temperature”.

White Balance (or “WB”) involves having the colour white turn out correctly in photographs that are taken outside of normal daylight conditions.

These types of conditions include Shade, where photos turn out blueish in color, indoors where orange/yellow light often dominates, and musicians performing under coloured stage lights.

White Balance is covered in full detail in our “How to Do Camera White Balance” article, which can be found at the following link:

How To Do Camera White Balance

Preset Modes on Cameras

Modern Digital Cameras have one or more fully “Automatic” modes, as well as special preset or “Scene” modes.

These generally do a great job of setting up the Aperture, Speed, and ISO variable values for us.

All we have to do is “shoot” or “snap” the picture, and the results look fantastic.

For example, if we set our camera to “Portrait” and take a picture of a person outdoors, it will turn out nicely with “bokei” (Background Blurring).

The Birthday Party pictures shown above were all taken using daylight portrait mode, which set our variables well, and also softened skin tones to make nice looking people photos.

However, if we set our camera to “Landscape”, the camera will make a nice bright picture where things both near and far from us are all in detailed focus.

Here is a great three minute video all about using Preset “Scene” Modes.

Auto and Scene Mode Limitations

Problems arise when we venture outside of normal daylight conditions, and attempt taking indoor shots without Flash, or we take portrait or party pictures with flash.

These “low light” and “Flash” photos often do not turn out as nicely as we would like them to.

We can Photoshop some of these pictures to improve them, but it is very time consuming.

It is better and faster to get good shots straight out of the camera by using Full Manual Mode, which will be discussed shortly.

Special areas of difficulty are photographing Rock Bands, Indoor Sports events, and Night Clubs, where there is not full daylight, and people are moving around.

On some Sony cameras, using “Sports” mode will sometimes produce reasonable shots in these conditions, and Canon cameras have a “Television” mode which sometimes works.

Full Manual Mode

In full Manual Mode we can adjust each of the three key variables of Speed, Aperture, and ISO individually.

It takes a lot of practice, and continual trial and error, to work out sets of variable values which work well in different lighting conditions.

However, we can generally get better looking pictures in “low light” doing it all ourselves, rather than leaving it to the “best fit” computer program that is in our camera’s processor chip.

Really it is a matter of getting to know the particular Camera we are using – Taking lots of pictures set on different Variable Values and seeing what happens is the only way to do this.

Whenever a picture taken using Preset or Auto Modes is not to our liking, then it is very useful to be able to change to Full Manual Mode and try and figure out the best variable settings for ourselves.

Here are some Manual Mode settings which we regularly use on the Sony A77 camera with a 16mm to 50mm f2.8 Sony Lens mounted on it:

Music Bands in local venue with Colored Lights:

– ISO 1600, Speed 1/60 and 1/125, Aperture F2.8, Incandescent or Manually adjusted White Balance

Music Bands with Professional Stage Lighting:

– ISO 400 to 800, Speed 1/125th, Aperture F2.8, F3.2, F3.5, Auto White Balance

Music Bands Using Sony f1.8 35mm Lens:

– ISO 400 to 800, Speed 1/125th, Aperture F1.8, Auto White Balance

Flash Shots People Pictures:

– ISO 1000, Speed 1/125, Flash Width Manually set on 50mmm width and 1/16 to 1/8 Power (Manual with No TTL) using Sony HVL-43M Flash unit.

Videos About Camera Settings

The following video is fifteen minutes long, but well worth watching, as it does many practical photo examples showing exactly what happens as camera variables are altered:

This next video is also fifteen minutes long and shows directly how changing variables affects the brightness and contrast of a given sample picture.

Here is Part 2 of the above video:

Camera Settings – Summary

All of this might be a bit of information overload at the moment, but by gradually working through all of our “How To” articles, and trying out different settings on your own camera, we are sure that you will become a much better photographer who is able ot problem solve situations quickly when your photos are not turning out exactly how you would like them to.

This article was an introduction to using Manual Camera Settings, there are far more detailed guides all about shooting in Manual Mode in the “Related items” section below.

Good Luck, and keep taking pictures!

Passy

PBP – Photos By Passy

Tag Archives: aperture

DIY Photography Course

How To Do Exposure

Using Camera Settings

Music and Special Events Photography and Video