Photography 101 : Full Frame vs Crop Sensor
For beginner photographers it can be difficult to fully comprehend how the size of a sensor will effect your photography. As someone who was a beginner not too long ago, I thought I’d take a stab at trying to sum this topic up. This is meant for beginning photographers, someone who has recently bought their first camera, or is looking into getting their first DSLR.
The basic difference between a full frame camera and a crop sensor camera is not difficult to understand. A full frame camera has a bigger sensor. Full frame sensors are about the size of 35mm film, while crop sensor cameras come in a variety of sizes. What can be hard to understand is how the size of a cameras sensor will effect your photography.
1) Effective focal range. This is by far the most important difference between full frame and crop sensor cameras to understand for a beginner. The first DSLR camera I bought was a Nikon D3300. It came with two kit lenses. Everything I read online said that the first lens I should buy beyond the kits lenses is a 50mm prime. I bought a 50mm prime. But it seemed to be more “zoomed in” than I was expecting. And I was right. When I put that 50mm prime lens on my D3300 camera, which is a crop sensor camera, my field of view was actually similar to a 75mm lens on a full frame body. When I went back to the articles I was reading about buying a 50mm lens they were all talking about for full frame cameras, only when I first read them I had no idea what that meant. When you buy a crop sensor camera, look up the “crop factor” and use that number to help you understand the “effective focal range” of a lens on your camera. The crop factor on a Nikon DX camera is about 1.5. Multiply the focal length of the lens by the crop factor and that will give you your “effective focal range”. Essentially, all lenses will seem more zoomed in a crop sensor camera than a full frame camera. Since so much information on the internet is talking about full frame cameras this will help you have the context to apply the information you read to the gear you own.
2) Bokeh. Bokeh is the blurred background you get for the out of focus areas of a picture. When you use a crop sensor camera less of the lens is actually in use. Since the sensor is smaller, it is in a way “cropping” the image as you are taking it. If you were to draw a circle that shows all the light passing through the lens and then were to draw the area of that circle that a full frame camera would capture and the area that a crop sensor would capture, the crop sensor camera area would be much smaller. The crop sensor is using less of the edges of the lens, and the edges of the lens can create more of that out of focus “bokeh”. This is assuming you’re using a full frame lens on a crop sensor camera. It seems to be more common these days for camera and lens manufacturers to make high quality lenses specifically for crop sensor cameras. These lenses are often smaller, lighter and cheaper than full frame lenses, and are designed to look great on crop sensor cameras.
3) Pixel density. Full frame cameras are known to be better in low light scenarios. One of the reasons for this is that the sensors are bigger. If you have a crop sensor camera and a full frame camera with the same amount of pixels, then the pixels on the full frame camera would be bigger. I don’t really understand all of the science and math behind it, but larger pixels are suppose to be better in low light, creating overall less noisy pictures.
4) Camera size and cost. Crop sensors are smaller, which also allows the cameras to be smaller. In addition, crop sensor cameras are often designed as beginner cameras which often have less features, which in effect helps keep them small. All of this also helps to keep these cameras cheaper. Any DSLR or mirrorless camera these days is going to take good looking pictures. Often what you’re paying for is features, pixels and software. Don’t be put off by crop sensor cameras that are much cheaper than some of their full frame counterparts. You can still take high quality pictures with a crop sensor camera.
What to do with this information?
I was very confused by all of this as a beginning photographer, and I’m sure many other new photographers are too. The earlier you understand the practical effects of the size of your camera sensor the more effectively you will be able to understand the information you are consuming about photography generally. This will lead to better decisions when it comes to buying new gear. I’m glad I was able to figure this out shortly after buying that 50mm lens. I was able to return it and get a 35mm lens designed for crop sensors. Though since transitioning to a full frame camera I have added a 50mm to my kit. The size of a camera’s sensor isn’t good or bad.
