Skip to main content

What is ISO and how it affects your DSLR photos.

If your low light photography pictures are coming out too dark or too blurry, ISO might be the solution for you. Back in the film days, ISO was known as the sensitivity of your film to light. Bigger the number, more sensitive it was and thus the photographer could take better photos in low light. In digital photography, it increases the sensitivity of your DSLR towards the light. Higher the ISO, the brighter and grainier images will look. Technically speaking, it increases the gain of the sensor which means amplifying the signal value.

Iso settings on a dslr
Pentax K5-II used to take high ISO photos
Value of ISO forms an integral part of the exposure triangle, where other two factors include aperture and shutter speed. Below are a few example shots showing the impact of ISO on photos taken in low light conditions. All the other factors such as aperture, shutter speed, metering mode and focal length were kept constant while taking these photos.
DSLR settings: 
Aperture: F/3.5
Shutter speed: 1/15 seconds
DSLR: Pentax K5-II
Focal length: 18 mm


DSLR photo taken at 160 ISO
ISO: 160

DSLR photo taken at 800 ISO
ISO: 800

DSLR photo taken at 4000 ISO
ISO: 4000


DSLR photo taken at 12800 ISO
ISO: 12800


From these 4 photos,  as a beginner photographer or camera owner, you can easily spot the effect of an increase in the value of ISO. As the ISO goes higher, the image keeps getting brighter and brighter, ultimately gets way overexposed. At the same time, if you zoom in, you will notice the images get noisy as well. Here noisy means a lot of grain, some people like the grainy look though but it does not look that appealing in people photos.

When do you increase the ISO?

When your shutter speed and aperture is not able to bring in enough light, that's where ISO comes to the rescue. Photographing a high-speed action? You will need higher shutter speed which will lead to loss of light. This can be compensated by an increase in the value of ISO which increases the gain. Photographing a low light indoors event, this is where you might have to bump up the ISO. Taking photos of moving bird/animal during evening hours, you will need an above normal shutter speed because the animal might move. This leads to less light coming in which can be balanced by increasing the value of ISO to boost sensor sensitivity to light. 
If a photo can be properly exposed and captured by changing the value of aperture and shutter speed only, then do not increase your ISO. ISO could be termed as the least preferred method to reach a perfect exposure in the photo.
Also, some cameras have a functionality called Auto ISO. This means you are leaving the ISO selection part to the camera. You will define the shutter speed and aperture, or either of them, the camera will figure out the value of ISO depending on the available light. With technology advancements allowing fairly high usable values of ISO, some professional photographers love to use Auto ISO in Manual mode.

If you found this post helpful and informative, share the photography love by sharing this post. :) 

Comments

Popular posts from this blog

Canon CR3 raw format guide

A raw image file is like a digital negative without any lossy compression and minimal processing applied to it. A digital camera shooting images in raw format provides output in the best possible quality, which means files are larger in size and take more space. The benefits offered by shooting raw format overpowers the slight storage hassle though. Few of the well known raw formats include CR2, NEF, RW2, RAF, PEF, ARW, etc.  In this post, we will talk about the new compressed raw format introduced by Canon starting with its mirrorless series of cameras.


History of Canon raw formats
Back in the early 2000s, Canon cameras produced raw photos in CRW format. Example of cameras shooting in CRW include Canon D60, Canon D30, Canon 10D, and Canon EOS 300D. Most of the cameras released after the year 2004 shoot raw photos in CR2 format. Examples of CR2 format Canon cameras include 350D, 6D, 7D, 5D, 5D Mark II and many more.
In 2018, Canon introduced its new mirrorless camera known as the EOS …

Relation between ISO, shutter speed, aperture and light in photography

Photography is a word having Greek roots, which basically means "drawing with light". When I started doing digital photography a few years ago, this did not make sense to me at all. How can you make a picture just using light? Only light matters? My pictures were either black or completely washed out all the time, but I didn't feel like giving up. It took me a fair amount of time to understand controls such as shutter speed, aperture and ISO which was the outcome of non-stop reading and a lot of mistakes. Coming back to the concept of light, it started to make sense after attending a film photography workshop. The dark room with very dim or near to zero red lights was a whole new point of interest. My partner and I made a pinhole camera out of a pumpkin. 
The workshop made me understand how important light is when taking pictures, and the rules apply to both film and digital photography. Basically, the value of shutter speed and aperture directly affect the amount of li…

Darktable vs Lightroom Classic CC

I first heard about Darktable software in 2016 and actually was quite fascinated with the name itself.  Within a few hours of hearing about it, I went to the official Darktable website and downloaded it on my Linux machine. Have been using it for quite a while now alongside Adobe Lightroom Classic CC and hence decided to write this small review post. If you are looking for a free Adobe Lightroom alternative, this might be or might not be for you depending on what you need.  Darktable is a free open source post-processing software which can do non-destructive RAW photo editing and photo management. Non-destructive means it does not change the original RAW file, all the edits are written to a sidecar file. It has evolved through so many phases of bug fixing and operating system compatibility. The latest version is available for Linux, MacOS, and Windows. Being an open source software it doesn't surprise me that it is available in 21 language translations. That's the power of op…