09 April 2009

Introduction to photograohy ISO

In the non digital era, 35mm films are the most popular medium use in cameras. And if you remember going into a photo / camera shop and ask for a box of film, the sales person will ask you what type of film you want? Or be more specific, what kind of photography you want to shoot or what ASA type.


After you have decided, he then hand you a box of film with a certain number on it, usually will be 100, 200, 400 or even 800. This number is know as ASA and it is representing the sensitivity of the film towards light. The higher the number, the more sensitive it is to light. The lower the value the less sensitive it is to light.

What this means is when using a ASA 100 on a bright sunny day, it will work great and but if you use ASA 100 for indoor shooting where lighting is low, then you will need lighting assistance. However if ASA 400 or 800 is use, then you may not need any lighting assistance if there’s sufficient lighting to give correct exposure.

However there’s a great drawback here. If you compare the ASA 800 with ASA 100 images, you will notice that ASA800 have more grains. This is known as NOISE.

Come back to the digital era. Digital cameras do not use any film. So what it has is a light sensor in the camera that can capture images like a film do, So like the characteristic of a film, the sensor has certain sensitivity toward light and this is represented as ISO. Understand ISO in photography is similar to understanding ASA. The only difference is you can change the ISO at any time you like depending on your photography environment.

In normal DSLR camera, you should get good range of ISO ranged from 100 –1600. Some higher end of DSLR may go as far as 3200 or 6400. This make low light photography much more interesting where films cannot do. By understanding ISO in photography it will help you in choosing the correct ISO for correct shooting technique.

Again with higher ISO, you will get higher noise but this depends on the equipment use, as some DSLR may have better noise reduction algorithm then other.

Here two picture taken with different ISO. Notice the grain on it. The higher ISO look much grainy while the lower ISO look smooth.

understanding iso

So How do you use ISO in photography?


Generally if you are shooting outdoor with good lighting, ISO 100-200 is preferred as it give smooth and less grainy images. However this got to take into consideration of the aperture and shutter speed setting, where correct exposure can be obtained.

EXIF : ISO 100, f7.1, speed:1/200s

If you are shooting indoor, or low light setting and you do not prefer to use a flashgun, then consider using higher ISO setting, such as 800-1600. Again, check your Aperture and shutter speed setting so that the ISO setting allows correct exposure.

For me I will always try using lower ISO value and slowly move upward to get the minimum light requirement. This is simply because I want to reduce the noise in my photos. If ISO 800 can do the job well, I will use it instate of ISO1600.

EXIF : ISO 1600, f4, speed:1/60s

Well I have just make an introduction to photography ISO. As mention before the 3 elements of photography; ISO, Aperture and shutters speed setting goes hand in hand with each other. It is important to understand all this 3 elements and how it effect you image quality.

If you have the needs to improve your digital photography techniques, pick up this free digital photography guide now.

Related posts:
Basic Element of Photography

2 Snaps:

How to use Photoshop or other recommended software to reduce the ISO noise?

http://www.softwhile.com/product_dn.html , try is photoshop plugin. There are many other noise reduction plugin for photoshop, but i'm using this, found quite useful.

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