Lets Talk Photography

Looking to learn more about the camera you are using.....well so am I so together we will take this journey together to explore the many ways you can use that expensive piece of equipment instead of using it like a "point and shoot" camera. Not that there's anything wrong with point and shoots, but don't spend the money for a DSLR camera and only use the "Auto" or "Program" settings. Life is about learning new things everyday so lets get out there and make beautiful pictures!

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Wednesday, July 27, 2011

ISO Speed


So to better understand shooting in low lite situations in relationships to newer DSLR's, here's a quick tutorial on understanding what exactly the ISO really does: 

The ISO speed determines how sensitive the camera is to incoming light. Similar to shutter speed, it also correlates 1:1 with how much the exposure increases or decreases. However, unlike aperture and shutter speed, a lower ISO speed is almost always desirable, since higher ISO speeds dramatically increase image noise. As a result, ISO speed is usually only increased from its minimum value if the desired aperture and shutter speed aren't otherwise obtainable.
low ISO speed high ISO speed
Low ISO Speed
(low image noise)
High ISO Speed
(high image noise)
note: image noise is also known as "film grain" in traditional film photography
Common ISO speeds include 100, 200, 400 and 800, although many cameras also permit lower or higher values. With compact cameras, an ISO speed in the range of 50-200 generally produces acceptably low image noise, whereas with digital SLR cameras, a range of 50-800 (or higher) is often acceptable.


exposure bucket analogy diagram
Achieving the correct exposure is a lot like collecting rain in a bucket. While the rate of rainfall is uncontrollable, three factors remain under your control: the bucket's width, the duration you leave it in the rain, and the quantity of rain you want to collect. You just need to ensure you don't collect too little ("underexposed"), but that you also don't collect too much ("overexposed"). The key is that there are many different combinations of width, time and quantity that will achieve this. For example, for the same quantity of water, you can get away with less time in the rain if you pick a bucket that's really wide. Alternatively, for the same duration left in the rain, a really narrow bucket can be used as long as you plan on getting by with less water.
In photography, the exposure settings of aperture, shutter speed and ISO speed are analogous to the width, time and quantity discussed above. Furthermore, just as the rate of rainfall was beyond your control above, so too is natural light for a photographer.

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