Some people believe that the path to a good photograph is a camera that has a sensor that can capture a huge amount of megapixels. However, this is only partially true, because not all megapixels are created equal. If you remember back in the dark ages when photographers used film, there were different film formats. Each film format designated the size of the negative. Negative sizes ran the gamut from the miniscule 110 film, which was used in miniature cameras and had a negative about the size of your thumbnail to large format cameras with negatives as large as 8 x 10 inches. When you start with a larger negative, you can create a larger size print.
The same is true of digital cameras. The miniscule point and shoot cameras that fit in your shirt pocket, have small sensors. Digital SLR cameras have larger sensors, full-frame DSLRs even larger sensors, and medium format digital cameras have even bigger sensors. If you cram a lot of pixels onto a small sensor, and put the same number of pixels on a larger sensor, the pixels on the larger sensor are bigger. Therefore all things equal, you end up with better image quality when you enlarge images captured with the camera that has the larger sensor.
When you have a camera with a smaller sensor, a lot of circuitry is confined to a very small space. Therefore the smaller sensor is more susceptible to digital noise. The increase in digital noise becomes more apparent when you increase the sensor’s sensitivity to light by increasing the ISO. At low ISO settings, most point and shoot camera yield acceptable pictures. However, when you push the envelope and take photographs in low light situations at higher ISO ratings, digital noise becomes apparent, especially in the shadow areas of the image. The digital noise may not be noticeable when you create a 4 x 6 print of the image, but will be visible when you create an 8 x 10 print of the same image.
|Camera Model||Megapixels||Sensor Size||Pixel Density|
|Canon G-10||14.7||7.6mm x 5.7 mm||34mp/cm2|
|Canon EOS 50D||15.1||22.3mm x 14.9mm||4.5mp/cm2|
|Canon EOS 5D||12.7||36mm x 24mm||1.5mp/cm2|
|Canon EOS 5D MK ll||21||36mm x 24mm||2.4mp/cm2|
The Canon G10 has the smallest sensor of the lot and is capturing 34 megapixels per square centimeter. The EOS 50D digital SLR has a much larger sensor and is capturing 4.5 megapixels per square centimeter. Even though the cameras capture approximately the same number of megapixels, the 50D stores fewer megapixels per square centimeter, which means the pixels are bigger and will yield better image quality when printed at larger sizes. I’ve also included the first generation EOS 5D and the new EOS 5D MKll for comparison. Both cameras capture fewer pixels per square centimeter. The newer camera features a different CMOS chip with advanced circuitry to lower noise, which means you can produce stunning images even though the camera stores almost an extra megapixel per square centimeter.
I own a Canon G-10 and the original Canon EOS 5D. I use the G-10 as an everyday camera. I’m pleased with the image quality of the G-10, but never capture an image with an ISO higher than 200 because of the noise factor. I use the EOS 5D to photograph weddings and events. I’ve captured images in low light with ISO ratings as high as 1600. Yes, there is digital noise, but the image quality is still acceptable. I could not get the same results with the G-10. I’ve created 30 x 40 prints with images captured by my EOS 5D. The images are crisp and sharp, even when viewed from just a few inches away. Although the G-10 captures more megapixels than my EOS 5D, it would not be possible to create an acceptable print larger than 11 x 17.
Don’t get me wrong. Small point and shoot cameras do have their place. They’re smaller, easier to carry, and less noticeable when you’re in a crowd. It’s also easier to take a candid picture of people with a point and shoot camera. When you point a digital SLR with a long lens at someone you don’t know, they almost always turn the other way. I use my point and shoot Canon G-10 often and love the convenience the camera affords. But when I need to take photos for clients, or capture images I’m going to enlarge, I always use my digital SLR to ensure the best results.