lesson 2 – understanding your camera and basics of exposure

Lesson 2 – understanding camera and basics of exposure

video tutorial




 

below you can see a full transcript of our video tutorial above

Second step in our series of free photography tutorials and beginners basics would be a good understanding on your camera and the relation ship with its parts, and also the translation of each part with its role in the exposure process. We have covered in the first lesson the light as the raw material for the photography, and now we are going to explore the tool. The painter needs to know his brush to be able to spread the paint on the canvas, the sculptor needs to have a good chisel to carve the stone.

Camera is a tool which helps the photographer to capture the image

 

Remember this, your camera is your tool, and focusing on the camera and not the subject will prevent you to see the big picture. It is very easy to get lost in the technicalities of cameras, brands, accessories, prices sizes, but at the end, the camera is just a tool, and not a purpose in itself.

Just like the human eye the camera has few important elements:

camera body which is basically an empty dark box with a sensor at the back, and a curtain which opens to allow the light to get in. The light is projected on the sensor which captures the light, sees the image, and records it. Very simple but very important to know and understand

the lens, or the eye of the camera is the the other important part of the camera.The lens will hep the image to be projected on the sensor for a short period of time during the exposure. The lens is very important as it projects a wider or more narrow image, a closer or a further subject, will allow more or less light into the camera

These 2 elements are the most important features of the camera as one does not work without the other and their quality will reflect in the quality of the final photograph. A camera works and is just like a human eye, the crystalline transparent muscle will allow the light to get in the eye, will sort out the distance, the focus and the intensity of light (your iris will become smaller in strong light and will become bigger in low light.

How camera works:

let’s discuss exactly how camera works, how an image is captured through one exposure. The sensor is a light sensitive recording device and it is a small surface of millions of little light sensors. I am not sure how the camera manufacturers are designing and building this but if you think about it, it’s pretty amazing. The sensor is placed in a dark room and it is exposed to light for a period of time when the curtain opens and closes. The curtain can be anything from 2 sliding doors opening and closing, or a vertical mirror or whatever , the important thing is that they close this cycle called exposure. So just to make it very clear we just came up with the definition of Exposure. During this “exposure” the lens allows the photons from outside to get in the camera projecting the image. ( we are assuming you have already went through the first tutorial – understanding light). The lens will allow arrange the flow of photons to be projected on the sensor which captures each photon in a small little bucket called pixel, cluster or whatever. Each bucket receive a number of photons coming from outside reflected by objects in nature as shown in lesson 1. Just to give you one example so you can visualise, enlarging an image on the computer, we’ll see each image is a sum of little coloured squares of an image. This is how each pixel is recorded by the sensor.

So just to say this in simple words, during one exposure, you press the button on your camera, opening a whole inside (with doors curtain or whatever), light is coming through the lens, is projected on the sensor who captures all the photons in tiny little buckets, and each bucket has an amount of light particles trapped, in a smaller or larger quantity with an overall specific colour.

Now it is very important to understand this concept. Each bucket can be empty,  no photons, that means, black point or dark, or it can be filled in various amount s until is completely filled, and overflows. If it overflows, there is a flood of light on the sensor and everything is becoming overexposed, we cannot see the individual buckets any more , it is all covered and we have an overexposed image tending the become complete white with no information on it. We have just explained OVEREXPOSURE. If there are not enough particles captured in buckets, the clusters will be under filled, so underexposed.  A good picture is defined when there is just enough particles in these buckets to reflect the reality.

Moving on, we can compare this directed flow of particles in the camera with rain falling onto a football field with buckets. Photons will always have the same speed (not sure why, you need to ask Einstein but apparently this is the rule), but they can come in larger or smaller amounts, and that is given by the intensity of the light. More particles, heavier rain, the buckets fill in faster. This is very important to understand, the more light outside, the faster the light sensor records  enough photons. This is the relationship between the shutter speed and the level of light, or between TIME AND EXPOSURE. More light need faster shutter speed, which means shorter time between the opening and closing the curtains. this is the justification and explanation of TIME as one of the 3 elements that influence the EXPOSURE.

Coming back to the sensor or the football field. If we have heavy rain, large number of particles, the buckets fill in a certain amount of time. If we have less particles falling, we need more time to fill those buckets. I hope it all makes sense. Lower light required more time.

Camera lens

I hope we understand now what happens inside the camera, but let’s talk about what happens with the light before it enters the camera. The lens has an opening, or a whole which is called aperture and that control the light intensity, or how many photons are getting inside. Larger the aperture, or the whole, the more photons get in….that means the shorter the time for the sensor to capture them. The smaller the whole, the smaller the aperture, less photons get in, the sensor needs more time. And this is the relation ship between the APERTURE and TIME  or the APERTURE and SHUTTER SPEED. I hope this makes sense as this is the most important concept in photography.

Moving on to the lens, on top of the aperture control, the lens is responsible for the focus, that means you get a sharper image or not but this is less important now and we will cover this when we will be talking about camera focus.

Basics of exposure – triangle of time-aperture-ISO

Let’s go back to the sensor and define one more and final concept which closes the basics of exposure. Each camera sensor has a specific sensitivity which is basically represented by the depth of the buckets. A deeper bucket needs, more photons to be filled, a shallow bucket needs less photons. That impact the relation ship between the Aperture (or the whole, or the amount of light) with the Time, or the shutter speed. For each bucket depth- sensitivity (ISO) there is a different amount of photons and time required to get a fill.  For deeper buckets – (that translates into less sensitive sensor) we need more photons to get in, to make a decent fill, that means we need more light, more time, bigger whole in the lens, so bigger aperture. More sensitive sensor = shallow buckets, means the fill faster with less light.

We have just defined the relationship between the TIME – APERTURE – SENSITIVITY or ISO and understanding this concept is the most important concept in photography. Once you get a hang of this concept, the rest is easy.

Understanding your camera

We has defined and explained the relationship above but how that work in practice? We need also to understand that a camera has the ability to see how much light is in front of it and make a selection of the shutter speed, aperture and ISO for a good picture. We are not going into how it does it right now, but we just need to understand that the camera can do it. Any DLSR camera today will have the facility of half press of the button to read what is in front of it, and decide in an instant which settings to use. That is called automatic camera and it can work pretty well for a large number of instances. That does not influence the sensor ability to record, and the camera can make a choice that you do not want assuming you know what you want. The sensor will capture whatever light is given to it without question. The problem is that camera has a limited number of choices as it is not intelligent to understand what you want and measuring what is in front of it can be tricky. That is why you need to take full control and tell the camera when to open, for how long, and how fast to record an image. once you can do that you are a photographer who is controlling the camera and not the other way, and you will get what you want and not what camera will give you.

 

 



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the best and shortest lesson in photography – exposure infographic

Exposure Info Graphic

the best and shortest lesson in photography

a picture says a thousand words. this one says about 50 thousands, and entire course condensed in one image. print this chart, laminate it, have it in your pocket and look at it when you pull out your camera and try to learn to control it.

exposure infographic

this is for beginners still trying to figure out the exposure triangle and what settings do what.
http://www.lifehack.org/articles/lifestyle/picture-show-you-clearly-the-effects-aperture-shutter-speed-and-iso-images.html



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understanding lenses – focal length vs F stop explained

focal length vs f stop

Understanding lenses – focal length vs F stop

Lesson 3 – basics of photography for beginners


In this tutorial we will try to understand the lenses, all relevant terminology in relation to them and explain the relationship  focal length vs f stop

In the Lesson no 2 –  understanding how to camera works and the basics of exposure, we have covered how the light enters the camera and how the image is captured. I would like to explore in more depth today what happens before the light goes into the camera and how the lenses are handling this task.

For a beginner all this talk about focal length, millimetres, F-stops, numbers and letters might be a little daunting at the beginning so I will try to make this as easy as possible, as it is very important to familiarise yourself with this terminology in order to learn photography.

I am going to define the role of the lens, few terminology explanations, few category and classifications of lenses, examples and a conclusion for you to take away and practice

Lens definition and specifications

Lens – is the optical device responsible for projecting the image in front of the camera to the sensor. The lens is defined by focal length , usually  expressed in millimetres, and the F- stop, or aperture, expressed usually from 1.2 to 22.

before we explain focal length we need to give you a 1 minute crash course in optics. The refraction is the phenomenon when the light changes direction when goes through a different transparent material, such as air – water or air to glass and vicevers. If the surface is not flat but curved, the light will be directed depending on the angle of the light. A lens is a designed glass element that has the ability to converge the light into on point.

Focal length vs Fstop

 

The focal length defines the distance between the lens and the focal point.

The question is why is this relevant? well this focal length reflects basically how wide a lens is. I do not wish to get more technical than this as it might take a long time to go through the optics and that is not the purpose of my tutorial. Let’s just remember the following rule.

Small focal length reflects to wide angles, and that means you can capture more, a bigger image, a wider image. Big focal length means a narrow image, means a smaller picture.

Example – the widest lens is the fish eye which has the focal length of 8 mm and that means the angle of view is almost 180 degrees, that means you can see objects on the side that your normal eye cannot see unless you turn your head. usually the widest images come with optical deformation which can or cannot serve your intent

The narrow lenses start about 400 – 1200 mm, that means their focal length is 40 cm to 1 meter 20 away from the lens, and that means the image is very narrow. These are the telephoto lenses and their purpose is to capture images with the subject far away.

You do not need to go deeper than this as it might be daunting for people who did not study the optics, but let’s stick a the simple rule:

smaller numer – wide image

bigger number – narrow image

focal length006

There is a wide variety of lenses out there, with variable focal lengths, called zoom lenses and they can go between various naumbers. You can play with the lenses and you should be able to learn all of this by associations without going into physics, but in time you will understand by intuition all of this focal length relationship.

F stop – is defined by aperture size, diameter of the whole of the lens

f stop

F stop is expressed in F numbers starting with 1.2 for the biggest aperture to 22 as the smallest aperture for a normal lens. There might be other lenses outside this range but it is irrelevant for our discussion. They F stop is basically how smaller the hole in comparison with one inch.

see here the technical description behind the f-stop

 

Just to make things simple, please remember one thing, F 1.2 is the biggest, and F22 is the smallest.

Going back to the previous lessons, large aperture = more light requiring faster shutter and that is why people call them fast lenses , small aperture = less light – need more time for exposure means slow shutter speed = slow lens. Lenses are not fast or slow as they do not move back and forth, this is just a naming convention for easy use of terminology

I think this is enough technical information. Once you get used to these numbers after spending a bot if time playing to whatever lens you might have, it will all come natural as a habit and you will know what this lens does what.

So in conclusion, we have explained briefly the relation ship focal length vs f stop,  please do not hesitate to send us any questions or queries and if you are a beginner, following the tutorials in order to help you become a competent photographer in a very short period of time

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aperture and depth of field explained

Aperture and depth of field explained

as a result of another online query from one of our subscribers, In this article I am going to explain how the aperture and depth of field are connected. This will be an optical explanation and it is addressed to people with a bit of understanding of optics. As I have discovered there are among our readers technical savvy who can understand and appreciate this information

before getting deeper into the technical explanation, I would like to point the previous tutorials that will support this info

Understanding light in photography

Depth of Field tutorial

Let’s remember few things:

– light comes from a light source as photons and waves, bounces on our subject and camera captures the bounced light which goes through the lens onto the sensor

– light changes direction when it changes the material it goes through, such as air and glass in our case but it applies to all transparent materials, like water, petrol, diamond and so on.

– the spherical shape of a lens can make the photons converge to a single point. If the curvatures of the lens are not perfect, the light convergence will not happen.

– every lens or combinations or lenses are acting as one

– for each point in front of the lens there is a correspondent converging point beyond the lens. Depending on the distance between the sensor, lens, and the subject, we have only one situation when all the light from one single point turn into another single point on the sensor. Only in this instance we have achieved perfect focus. If this relationship is not right, and the point of convergence is in front or beyond the sensor, when for one point in the image, we have an area projected on the sensor. This means out of focus or a blurry result.

– for each instance there is one continuous distance from the camera which is the focus plane, in reality it is a focus sphere. all points situated closer or further than this virtual sphere will not have single points corresponding on the sensor but spots which are over one another and this is the out of focus blurry effect. It is a reality than the focus sphere has a depth in which the human eye cannot perceive small differences and it is acceptable as a reasonable sharpness. This is the depth of field, or the depth of the focus sphere.

– aperture is limiting the light cone in the relationship described above which sometimes decreases the size of the areas corresponding to a single point in the scene. The purpose of this is to bring more space into the acceptable depth of field, or let;s just say making focus sphere deeper, so more objects appear in focus, and decreasing the blurriness overall.

So this is the relationship between the aperture size and the depth of field. the smaller the hole,  the sharper the image will be. If you do not have a perfect natural vision, and you are trying to look through the tiny holes created with your hands, you will notice that the images are sharper, regardless of the glasses your are wearing. of course the image is going to be darker, as you limit the amount of light going through, and that applies to camera sensors as well which limits the exposure level and requires longer exposure times, and that is the other exposure triangle element, the shutter speed but that is not what we are talking about here

 

I hope I have shoed very clearly how the aperture and depth of field are interconnected and what will help you understand easier the basic exposure.

If you have any questions, please leave your comments done below

thank you

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aperture priority mode explained

f stop

Aperture priority mode

Aperture is defined as the size of the whole that allows light into the camera to reach the sensor.

The larger the whole, the more light gets in, the lese time is needed for exposure . If you set up the camera on aperture priority, the shutter speed will be varied automatically to achieve the good exposure. You need to select the Av mode on your camera. Before we move on, we need to understand what the F stops (or aperture values) mean.

The aperture value is usually expressed as a fraction. F2.8 means 1inch/2.8 which translates basically into a hole of 2.54 cm / 2.8 = 0.9 cm which means 9 mm diameter hole. It may not seem that much but this will allow plenty of light for a decent exposure for most of the cameras.

The wides aperture (hole) available on the market is F1.2 = 2.54cm/1.2 = 2.11 cm. Usually these lenses with this wide aperture are quite expensive for the average consumer

In order to understand this mode, you can fix the aperture to f4 or F5.6 for example, set the ISO to 100 and see what happens. The camera will attempt to modify the shutter speed automatically in order to obtain a proper exposure. The issues with this mode is that depending on the light levels in front of your camera, you might get a blurry picture if the camera chooses a slower shutter speed than 1/125.

The aperture is limited by the lens you have. A good lens will be have the maximum aperture up to 2.8.
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understanding exposure

Understanding exposure

Basics of photography for beginners

Understanding exposure will help you also to start your journey in photography. We have covered how the sensor is recording the image in the article “Understanding the camera” One thing to mention is that there is no absolute correct exposure. It depends also on the taste of the person looking at the image. I always like my images being lighter, but overexposed after other people expectations.

I would say at this stage after years of photography that a correct exposure is when the image reflects the reality best.

Thanks to today’s digital photography era, an image can be controlled before it gets downloaded from the camera to a different medium. There is always an error margin that can be fixed on the computer later. So I am no longer concerned getting it right, as the image can be processed later.

This is also combined with selection the RAW option of the image format as an output for the camera, (assuming you are using at least a DLSR with this option). The RAW image is an unprocessed map of pixels.

This article needs to be read in conjunction with RAW versus JPG format. Just as a quick mention, is the fact that shooting RAW pictures, basically you can retain all the information that camera captures during one exposure.

 

understanding exposure

As per image above you can clearly see that dark areas appear as almost complete black and all details disappear.

This is the best example of under exposure.  This can result wither form the fact the area is dark in reality and camera is not able to pick up any details, or the image does not have the time during one exposure cycle to capture enough light

Either way we can observe the fact that an image does not necessary needs to be underexposed as a whole, in order to have only parts of it underexposed.

A proper exposed image can still have underexposed parts of it, and also overexposed. This is not what we would call it a preferred image due to high contrasts and loss of details

 

In the same way we can have areas of the picture or as a whole overexposed, where too much light burns the image to the extent of complete white, to parts or the whole image.

Overexposure comes with loss of details as well, where parts of the image become complete white.

So what is a correct exposure?

I would say the exposure that is in the middle, and it reflects the image in front of the camera the best, despite the fact there may be spots or parts of the picture under or o over exposed

Under exposed

image under exposed

images above there a details lost in the dark.

correct exposed

correct exposure

the correct exposure reflects the reality of the lighting level.

over exposed

image over exposed

image is lighter than the reality, details are lost in areas complete when to much light is creating a white area.

Just before we move to a different subject, one way to show all details of a particular image, we need to apply a HDR process, but this topic will be treated at large in a different article. It is an artificial process to allow us to see dark areas in the image even if the exposure is correct

A HDR (High Dynamic Range) image will have all the extremes (under and over exposed parts of it) brought to a middle level where all details can be easily seen.

HDR image sample

This technique requires a software which combines several images (different exposures) and all the details are artificially brought to an even level to be seen clearly. This create an effect which sometimes can be spectacular, however I personally do not prefer this technique as it creates a flat image with less depth

 

 

The correct exposure is a result of 3 factors:

–       Aperture

–       Shutter speed

–       ISO

These 3 factors are interconnected. To make a comparison again with the rain of a field of buckets, we can say that, the aperture is a filter allowing a certain amount of water falling, shutter speed would be the duration from the first drop falling on the field to the last one, and the ISO will be how deep the buckets are and how fast they can be filled

Considering a fixed bucket size (fixed ISO), a certain amount of rain will fill in a certain amount of time. More rain (wider aperture – more light) means that the buckets are filled faster (shorter time when the curtains are open – faster shutter speed). Less rain means buckets getting filled slower, means longer time required

This would describe the relationship between the aperture and shutter speed. Wider aperture requires faster shutter speed and narrower aperture means longer time required, slower shutter speed.

This relationship can be noticed when you fix the ISO  and  vary the other 2 settings: aperture and shutter speed. This can be done by setting the camera in the Program Mode or Automatic mode.

My changing either one of them, you an notice the other if changing as well, in order to compensate.

That is the relationship between shutter speed and aperture.

If you modify the ISO, this relationship will change slightly, but they will act in the same way.

Just to be clear, the same exposure can be achieved with different settings.

In order to have a better control of the camera, you need to select either the stutter speed Priority Mode (Tv) or aperture priority (Av). What this does, will fix one of these 2 settings allowing the camera to select the other for you. Selecting the ISO to 100 will give you the best outcome. Increasing the ISO will give you faster results. The higher the ISO, the grainier image you will get. The results are pretty good these days to ISO up to 800.

This is how I shoot and usually I keep the shutter speed on 1/125th of a second to keep the sharpness and let the camera choose the aperture. In most of the cases this will work just fine.

As a professional photographer I use this setting 90% of the time I am shooting within reasonable lighting levels.

Best exercise of mastering this triangle Shutter speed – Aperture- ISO my suggestion is to do what I have done. Put the camera in complete manual mode, and you will be able to manually set up each of these. Set the ISO to 100, the shutter speed to 1/125 seconds and vary only the aperture and see what happens. You can go up and down on aperture until you have either a complete underexposed picture or an overexposed one.

Do the same thing setting up a faster or slower shutter speed and discover what happens

Going back you can set the aperture to a fixed 4 value and modify the shutter speed accordingly

You should get similar results

After going back and forth, you can fix both shutter speed and aperture and work on the ISO and that will give you a measurement and understanding how ISO works

For all these exercise you will need a tripod as for slower shutter speeds than 1/60th of a second, the camera will pick up you hand trembling and you will get a blurry picture you can use for comparison.

By experimenting this way, you will get the idea how this all works within few hours of trial and error, without spending time and money trying to get paid course of other people teaching.

For computer savvy new camera users, if your camera will have the facility of being controlled live by a computer, the results will come directly on your screen and you will learn even faster. – Check you camera documentation for more results.

Before I was about to become a dedicated professional photographer, my first lessons were done at home trying everything until I have understood the results I was going to get and not being surprised at all: I was in control
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