APERTURE, SHUTTER SPEED & ISO

One of my friend asked me, "what is aperture, shutter speed and ISO, I don't understand  what is the link between these three to take good picture?"

So today,  I am going to talk about these three.

Before going any further, first we need to understand the concept. Let us consider one by one:

1. Aperture: 

If you see through a lens, you will see some blades are there and they make the small or lager hole. If the hole is small, the less light enters and just opposite to this, if the hole is large, the more light enters. Aperture also controls the depth of field. The wider the aperture, the shallow depth of field. The smaller is the aperture, the long depth of field we get. Aperture is measured in "f" numbers like f/1.8, f/2, f/2.8, f/4, f/5.6 ..... f/18, f/22.

Wider Aperture =        More Light eg. f/1.8     =          Shallow Depth of Field

Smaller Aperture =     Less Light eg. f/22       =          Long Depth of Field

2. Shutter Speed: 

When we talk about shutter speed, it is the time of shutter to let the light into the sensor to properly expose the picture. Shutter speed is measured in "fractions of a second" like 1/10, 1/15, 1/25, 1/50, 1/60 .... 1/3200, 1/4000.

Slow Shutter Speed = More light into the sensor =   Good for low light situation

Fast Shutter Speed = Less light into the sensor =     Good for freezing motion       

3. ISO: 

We can say that ISO is sensitivity of camera to light. It is pronounced as "aiso" (just to explain I am writing in this way) and not I S O differently. This is measured in "numbers" like 100, 200, 400, ... 25000. Lower number means lower sensitivity to light and higher number means higher sensitivity to  light.  We get good quality pictures if ISO is in lower number and grain/noise if the ISO is higher in number.

Higher ISO =   More Sensitivity to light =       More grain/ Noise

Lower ISO =   Less Sensitivity to light =        Good quality/ Less Noise 
From the above we are in a position to understand that what is Aperture, Shutter Speed and ISO. It is also necessary to understand that how these three works in together, what is their impact on a photograph and under what situation we have to use aperture mode, shutter mode or manual mode.
APERTURE:

Now we know what is Aperture, Shutter Speed and ISO but to explain it more I will try to explain each concept with some photographs. We will see it in more details and how these are affected.

These three, Aperture, Shutter Speed and ISO are just like three legs of a tripod. The whole photography depends on these three things. We get a good quality photo when these three are well balanced and you can balance them only if you are well aware of these three things. One can understand it better if he has practiced a lot. Let the photo be good or bad, first concentrate on understanding the function of camera by controlling each and every mode. When we talk about good photography on the basis of these three settings then we must also not forget that distance from subject also matters.

So, considering the situation we have to keep the aperture, suppose we have to photograph a well lit subject then we don't need to increase the ISO, if we want to capture that subject with shallow depth of field then we have to keep aperture wide open and shutter speed needs to be fast.

We will continue with Aperture, how can we get shallow depth of field and long depth of field. This has been tested from the same distance and with the same lens 50mm at different aperture.

In this picture figure(a) you can see the shallow depth of field, rose in background is completely out of focus, here I set the aperture f/1.8.

figure (a) Aperture f/1.8

In this picture figure (b) you can see the shallow depth of field, the rose in background is out of focus, here I set the aperture f/2.8.

figure (b) Aperture f/2.8

In this picture figure (c) you can see the shallow depth of field, the rose in background is blurred, here I set the aperture f/4.

figure (c) Aperture f/4

In this picture figure (d) you can see the depth of field, the rose in background is quite blurry, here I set the aperture f/5.6.

figure (d) Aperture f/5.6

In this picture figure (e) you can see the depth of field, the rose in background is less sharp, here I set the aperture f/8.

figure (e) Aperture f/8

In this picture figure (f) you can see the depth of field, the rose in background is little blurry, here I set the aperture f/11.

figure (f) Aperture f/11

In this picture figure (g) you can see the long depth of field, the rose in background is in focus as compared to others, here I set the aperture f/16.

figure (g) Aperture f/16

If we want to practice, in this way we can keep on changing the aperture and then its effect on background of the subject, in this way we can find out that which aperture brings the sharpness and details in subject and also how far depth of field is affected.

We can do the above exercise by keeping our camera in Aperture Priority Mode. This will automatically adjust the shutter speed, but one thing that we have to keep in mind is ISO has to be lowest.

Friends, the way I am presenting here is also my way of learning. I don't know what is your opinion about my way of explaining, but I am trying hard at my level to explain it as simply as I can. 

SHUTTER SPEED:

When we talk about shutter speed, it is referred for motion. With shutter speed we can easily freeze the moving object. Suppose a child is playing in field and we have to capture that moment then we have to increase the shutter speed, it means we have to keep fast shutter speed, we may keep it 1/500 sec. If we keep the slow shutter speed then it will blur the image means photo will not be clear. Many a times we have seen that when we are taking a picture and suddenly some movements take place like hand or head movement of a person then it creates ghostly image which is the cause of slow shutter speed. It means that longer time passed for the movement to be recorded in the camera, which results in blurred image.

Slow Shutter speed is also used to create the many effects in photography like light trails, softly moving water, to capture a beautiful scene where public movement is more to get the scene only and to avoid people movement, lightening can also be photographed.

Fast shutter speed is used to freeze the motion like jumping people, falling water drops effect, running person, moving vehicle, bird on flight.

Here we will try to understand the effect of slow shutter speed and fast shutter speed, using fan. The blades are moving and we will see that after keeping shutter speed in 1/30, 1/60, 1/125, 1/250 and 1/500 what effects do we get in our photo. Through this example we will be in a position to understand that how can we control the movement and can give desired effect to the moving object.

My basic intention of taking topic one by one is to understand each concept in depth so that when we are out in photography we don't have to think much about these things. This should get stored in our subconscious mind. All settings should happen automatically as per the situation, our mind should respond to particular situation immediately.  

From figure-(i) we can see that fan blades are moving as usual what we see with our naked eyes, this is taken with shutter speed of 1/30.

figure-(i) shutter speed - 1/30

From figure-(ii) we can see that fan blades are blurry, this is taken with shutter speed of 1/60.

figure-(ii) shutter speed - 1/60

From figure-(iii) we can see that fan blades are moving and are blurry, we can see ghostly effect also, this is taken with shutter speed of 1/125.

figure-(iii) shutter speed - 1/125

From the figure-(iv) we can see that fan blades are moving and are blurry but we can see that more motion freezing effect than the previous one, this is taken with shutter speed of 1/250.

figure-(iv) shutter speed - 1/250

From figure-(v) we can see that moving fan blades are mostly frozen, this is taken with shutter speed of 1/500.

figure-(v) shutter speed - 1/500

From above figure we can see that how the motion can be frozen with the increased shutter speed and how can we give ghostly effect also. 

If you find something missing you are free to comment and I will try to cover that also. If you like that also matters a lot to me. 
ISO:

We have already seen that how aperture and shutter speed works and now we will see that how ISO works in tandem with shutter speed. In this we can keep aperture constant and have to move shutter speed according to increased or decreased ISO.

It is always regarded as good  to stick to the lowest ISO (base ISO) of your camera, which is typically ISO 100 or 200, whenever possible. To maintain the image quality, it is best to use lowest ISO if good lighting is there. If it is dim light situation then in that case you have to increase the ISO and if you want to keep to lowest ISO then you have to mount the camera on tripod because then you have to reduce the shutter speed

Whenever I have to shoot indoor without flash then I have to increase the ISO to a level that the shutter speed is enough to take the shot hand held. sometimes we have to intentionally increase the ISO that depends on situation like birds on flight shot, this needs increased shutter speed and therefore ISO needs to be increased.

In most of the DSLRs, there is setting of Auto ISO, in this we can set the maximum ISO and when we take a shot it doesn't increase the  ISO more than the set limit.

Typically, ISO numbers start from 100 (Base ISO) and in some it is also 50 and it increases even to two lacs or more.

Each time you double the ISO for an exposure, the camera needs only half as much light for the same exposure, e.g. if you had a shutter speed of 1/125 at 100 ISO, increasing it to 200 ISO would let you get the same exposure at 1/250 second. This is why high ISOs are often used indoors, especially for bird on flight and  sporting photography. To stop an action fast shutter speed is needed and  photographers regularly choose high ISO

Higher ISO brings noise/ grain in the image and maximum it is tried to avoid noise in image. Sometimes photographers intentionally keep grain in their images to bring effect in that like images with dew or water droplets they create a different impact.

Now a days in digital SLRs a new revolution has come with the good quality image even keeping ISO at 1250 or 1600.

A better understanding of ISO along with Shutter Speed and Aperture will help you make smart decisions about how to set your camera and that, in turn, will lead to a good quality pictures.

Here I will show you with pictures how increased ISO increases the grain or noise in the image.

Left image with ISO-200 & Right image with ISO-3200

If we give a close look we will find grains in the image with ISO-3200 and it also affects the exposure. The above image makes it all clear. Here we have completed the topic "EXPOSURE TRIANGLE" and the three pillars of photography i.e. Aperture, Shutter Speed & ISO.

I have tried my level best to explain this topic and hope that you all will like this. If anything I missed out let me know by your comments.