Happy New Year Everyone 🙂 . Welcome back to Camera and Clicks.
Hope you had a great vacation. I had a long break. Holiday season includes a lot of fun things like family get together, travels, happy memories, gifts and yeah photos( lots and lots of it ) . This year I received two great gifts 1) A new lens on my birthday 2) A book of my most admired photographer Bryan Peterson “Understanding Exposure” These past two weeks I have been just reading and shooting. Reading this book has helped me improve my photography a lot.
In my previous post “ 3 Easy steps to Improve your Photography” I have said that before taking a photo, it’s better to decide on your theme and the rest falls in it’s place. Today I am going to talk about the next step “Exposure ” . A perfect exposure is something every photographer tries to achieve in every shot. So lets go on with the basics of photography.
Exposure is the amount of light captured by your camera during each photo. If the camera captures more light then the photo appears to be too bright and/ or the main subject looks blown out. If the camera captures less light then the image appears dark. So what is this perfect exposure ? How can we achieve a perfect exposure ? There are three things which control exposure 1) Aperture 2 ) Shutter Speed 3) ISO.
The three settings which control the exposure are complementary to each other. A change in any one of the settings will change the other two.
Lets get to know each of them
It’s a hole through which light enters your camera and hits the sensor. If the hole is bigger more light enters the camera, if it’s small less light enters the camera. Aperture is denominated as f-stop values. For example f/4.2, f/11, f/20, etc. These numbers represent the diameter of the hole. Lets go back to some basic mathematics, don’t worry I am not going to ask you formulas of circles diameter or it’s circumference, etc. Geometry was never my favorite subject. Lets talk about fractions, in fractions we know that if the denominator is big then the overall value of that fraction is small. Based on this we can say that f/22 is small, as a result a small aperture and f/2.8 is a big value , as a result a big aperture.
Aperture not only controls light, it also has a different function which is known as ” Depth of field“. Depth of field (DOF) is the part of the image that appears to be in focus.
The smaller the aperture, like f/22, f/ 28, f/32 gives you a broader depth of field i.e. the foreground and background appears to be in focus.
The larger the aperture, like f/2.8, f/4.2 , f/ 5.6 gives you a shallow depth of field i.e. only a part of your photograph appears to be in focus.
2. Shutter Speed
It’s a curtain which controls the amount of time the sensor is exposed to light. It’s expressed in terms of seconds. Shutter speeds range from 30, 15, 8, 4, 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000, 1/8000. These numbers indicate the time the sensor is exposed to light. Each number is double than it’s preceding value indicating double amount of light hits the sensor.
Shutter speed controls motion. Faster shutter speeds like 1/1000, 1/500, 1/250 freeze the motion. slower shutter speeds like 1/30, 1/2,1sec, 2 sec , etc. causes blur/ captures movement in the photo.
ISO controls the sensitivity of the sensor to light. ISO values range from 100, 200, 400, 800, 1600, 3200 and 6400. The lesser the ISO value the lesser the sensitivity of sensor to light indicating more light is required to get the correct exposure. The higher the ISO value the higher the sensitivity of light indicating less light is required for correct exposure.
Higher ISO have a disadvantage. The higher the ISO the more the noise or grain in the image. The grain or noise might not be visible on the LCD of your camera but when viewed on a computer screen, it becomes much clear.
Look at the photo at the right, the photo was taken at an ISO 12800. Do you see a disturbance in the photo, small box like structures in the background. That my friends is the grain or noise that I was taking about.Higher ISO causes grain in a photo.Now it brings us to the question when to use higher ISO values. I have listed a few situations where I find it helpful to increase ISO values.
When to Increase ISO values
- In low light conditions.
- When the use of artificial light is prohibited ( example camera flash, external flash, etc)
- When you are camera is hand held rather than on a tripod.
- When your subject is moving and you can’t get a faster shutter speed.
- When you intend to have a shallow depth of field under low light conditions.