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Frequently Asked Questions about Digital Camera Sensors

By Edited Apr 29, 2015 2 5

Digital cameras are now commonplace. Most consumers with a camera have one. However, when you're shopping for a new camera, it pays to think a bit about the features and technology behind the camera you buy if you want to get good image quality. Two of the most important things to consider in regards to image quality are the lens and the sensor. Unfortunately, the average point and shoot buyer, spends little time considering these items.

When it comes to the sensor, a number of questions can come up.

1. Why is the sensor so important when buying a digital camera?
With a digital camera, the lens focuses the light on the sensor and the sensor gathers that light and converts it into electrons. The sensor determines how much detail (resolution) and color accuracy your pictures will have.

2. How do I know the resolution of a camera's sensor?
In digital photography, the resolution is measured in pixels; often expressed as megapixels or pixels x 1,000,000. When you see a camera with an 8 megapixel sensor, it means the sensor has 8 million points of graphic information to display to provide the color and detail. Therefore, a 12 megapixel sensor offers more detail and color information than a 6 megapixel sensor.

3. It sounds like more megapixels makes for a better sensor?
Not always. When viewing photos on a computer or printing them as 4 x 6 or 5 x 7 images, it becomes hard to tell the difference between the detail provided by an 8 megapixel sensor and a 10 or 12 megapixel sensor if all else is equal. Printing 4 x 6 or 5 x 7 images with good resolution requires only a 3 or 4 megapixel sensor, while larger images such as a 9 x 10 might require a 5 or 6 megapixel sensor. Stated simply, a large area requires more information to offer the same degree of detail.

In some situations, more pixels can create problems. For instance, lets say you have an average point and shoot digital camera with a 1/2.5" sensor; both sensors have the same area. One however, has 8 million pixels and the other 12 million pixels. Both are squeezed into the same area. That means that the sensor with 12 million pixels has smaller "photosite wells" and the one with 8 million pixels has larger "photosite wells". Larger photosite wells gather more light. Therefore they are more "sensitive" to light. If the sensors are the same size, then the 8 megapixel camera may produce sharper looking images, especially in instances where lighting is limited, such as indoors, in the shade, or in the evening. In this instance, the images created with the 8 megapixel sensor may offer more detail and better contrast.

4. So is an 8 megapixel sensor always better than a 12 megapixel sensor?
Not necessarily. You also have to consider sensor size. Larger is better in general. Thus, if you have a 1/2.5" sensor with 8 megapixels and a 1/2.3" sensor with 10 megapixels then the 10 megapixel sensor has the resolution and the photo gathering capability you want for great detail in your photos. Remember, megapixels make sense in relationship to the area they are spread across. If there is more area, then the pixels won't be crammed into the same small space, photosite wells will be larger, and more light can be captured, and detail created.

5. Are all sensors equal aside from the resolution they offer?
No. They can employ different processes for filtering color and so forth. For the average consumer though, you can just note that there are different types of sensors, CCD and CMOS sensors. CCD sensors are more light sensitive in general but use more far more power. However, there are now backlit CMOS sensors. These backlit sensors have greater light sensitivity and cut down on the artifacts that occur in images taken in low light situations.



Feb 11, 2011 9:11am
Very informative. Congrats on feature.
Feb 25, 2011 10:05am
Digital cameras can be so confusing. Thanks for the info!
Mar 3, 2011 9:56am
It's always good to learn more about the electronics we use. Enlightening post.
Mar 21, 2011 7:17am
Photography is a hobby of mine. Until approx 5 years agoo - I was faithful to my "film camera" - much needed infomation for the digital SLR's. Thank you.
Oct 8, 2011 5:35pm
If you take a pictures at the max resolution of a sensor and then take one at a lesser resolution (say 15 vs 10MP) are the pixel sizes at both resolutions the same (proportionally less of the sensor is used at 10MP) or do both resolutions use the full sensor to record pictures?
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