Photo Talk: The Skinny on Sensors

To start I must say I was rather surprised this weekend when I found out that people are actually reading my blog and liking it. A big THANK YOU!!, to you.

When I discuss a topic I like to keep it as simple yet informative as possible. I find some sight over complicate things or get too deep in the subject. I like to think there are a lot of people that want to learn more but do not want to read something that takes a college degree to read.

With that said, lets talk sensor size, mega pixels, and the clarify that more is not necessarily better, but bigger is better.

Most of you probably remember what 35mm film looks like, I mean in reference to its size. The negative is the original, your master image. The data captured on a 35mm film can be enlarged but you will get to a point where the clarity is lost and the enlargment starts to look not so good. The negative is 35mm wide, about 1 3/8 inches. When you print a 4x6, 8x10, and 11x14 print from a 35mm negative you can see the clarity begin to diminish.

Do you remember the old 110 film and how small it was? It was 16mm wide. In this case your source is a little more than half the size of a 35mm. You can image the clarity loss as you print a 11x14 print from a .63 inch master.

I tell you all this to help explain what is going on with digital sensors and why more megapixels is not necessarily better. Sure the marketing will tell you it is, they want you to buy the camera. But really...sometimes less is more.

Here is a little image breakdown to show you comparison of sensor size. Of course this is not actual size but I am sure you will get the idea.

A sensor that is equivilent to a 35mm piece of film is called "Full Frame Sensor". Professional camera bodies are the ones that will have a full frame, or 35mm wide sensor and will cost you some serious cash. The most common size sensor in Digital SLR's is the APS-C which is 22.7mm wide. Many of the compact cameras have sensors that are 5.3mm wide. You can see already the difference in the size of your master image and the impact it will have on how large of an image you can really print.

Now that we have established some groundwork in sensor size...lets talk megapixels.

Don’t be fooled to think more is better. An APS-C sensor is 22.7mm wide and its size does not change with the addition of more and more megapixels. For the Mfg. to go from 10 MP to 15 MP the actual pixel must be smaller to crunch them on the sensor. In this example, 5 million pixels squeezed on the same sensor that once held 10 million.

Each pixel gathers light and exposed to color. One would think that having more is better. In fact you must remember that each of those pixels are now smaller, meaning it could take more light to maintain or increase effectiveness.

Everything I have read about the Canon 40D vs the Canon 50D indicates that the 40D is better in higher ISO noise. The 40D is 10.1 MP camera and the 50D is a 15.1 MP camera.

The big megapixel cameras (21.1 MP) for Canon are the 1Ds Mark III and the 5D Mark II which have full frame (35mm wide) sensors. Interestingly the other pro body from Canon (1D Mark III) which has an APS-C (22.7mm wide) sensor, has only 10.1 MP’s.

I think it is easy to conclude that more MP’s is not necessarily better. I am convinced the camera companies are building what you are willing to buy. As long as people think that more MP’s are better, they will continue to build and design entry level and advanced amateur cameras with more MP’s.

A good example is the compact camera world. Look at the size of the sensor in most of these cameras. It is like 5.3mm wide which is less than a ¼ inch.

Learning what you have, it is easy to conclude that 8MP on a DSLR (APS-C sensor) is much better than 8MP on a compact camera sensor.

I have had two compact cameras. My first was 2.1MP and the latest is 7MP. I have taken far better images with the old 2.1MP by far.

The two images above were taken with my Sony 2.1 MP camera. In a small compact camera I personally think less MP's are better. A 2.1MP image will make a good 4x6 print. Much bigger than that and quality drops.

The Canon 300D I took to Africa in 2007 was a 6.1 MP camera. It is my opinion that in most cases you do not need much more than 8 MP's unless you do a lot of cropping.

Please remember, a DSLR sensor is nearly 4.5 x's larger than a compact camera sensor. Even though a compact camera may have 8 MP's, the potential for top image quality is just not there.

Here is a little tool to help associate MP's with print size.

The point of this blog is to help you become informed and to encourage you to do a little more research as you seek to purchase what may be your first DSLR. Do your research before you buy. There are several great review sites.

Fred Miranda

The Digital Picture

SLR Gear

Digital Photography Review

Cross reference the reviews. Don't rely on one review to make your decision. You are investing a fair amount of money and you want to be confident in your purchase.

Even as I plan on upgrading, I will choose the Canon 40D over the Canon 50D. I am not looking for MP’s, I am looking for top quality.