As a new photographer, you may have heard the term “crop factor” thrown around when discussing different camera bodies and lenses. But what exactly is crop factor, and how can you calculate it? In this blog post, we will go over everything you need to know about crop factor in photography and how to calculate it.
What is a Crop Sensor?
Before we dive into crop factor, let’s first define what a crop sensor is. A crop sensor, also known as an APS-C sensor, is a type of image sensor used in some digital cameras.
Compared to a full-frame sensor (which has the same dimensions as a 35mm film negative), a crop sensor is smaller. This means that when you take a photo with a crop sensor camera, the image is “cropped” or zoomed in compared to what you would get with a full-frame sensor.
What is Crop Factor?
Crop factor is a term used to describe how much smaller crop sensors are compared to a full-frame sensors in a modern digital camera. It is a number that represents the ratio of the diagonal size of a camera’s image sensor to the diagonal size of a full-frame sensor. For example, a crop factor of 1.5x means that the diagonal size of the camera’s sensor is 1.5 times smaller than the diagonal size of a full-frame sensor.
Why is Crop Factor Important?
Crop factor is important because it affects the field of view of your lenses depending on which digital camera you choose. When you use a lens on a crop sensor camera, the crop factor “crops in” or zooms in on the image compared to what you would see on a full-frame camera. This means that a 50mm lens on a crop sensor camera will have a field of view equivalent to a 75mm lens on a full-frame camera with a crop factor of 1.5x.
How to Calculate Crop Factor
To calculate crop factor, you need to know the size of your camera’s sensor and the size of a full-frame sensor. For example, let’s say you have a Sony camera with an APS-C sensor. The diagonal size of an APS-C sensor is approximately 23.5mm, while the diagonal size of a full-frame sensor is 43.3mm. To calculate the crop factor, simply divide the full-frame diagonal size by the APS-C diagonal size:
Crop Factor = Full-Frame Diagonal Size / APS-C Diagonal Size Crop Factor = 43.3mm / 23.5mm Crop Factor = 1.84x
So, the crop factor for a Sony camera with an APS-C sensor is 1.84x.
Common Crop Factors
Keep in mind that crop factor can vary depending on camera manufacturers and sensor size. For example, Canon crop sensor cameras have a crop factor of 1.6x, while a 1/2.3 sensor (commonly found in smaller sensor point-and-shoot cameras) has a crop factor of approximately 5.6x.
Cropped Sensor Conversion
If you are used to shooting with a full-frame camera and are transitioning to a camera with a smaller sensor, you may wonder how to convert your lenses to match the new field of view. The easiest way to do this is to multiply the focal length of your lens by the crop factor. For example, if you have a 50mm lens and are using a camera with a crop factor of 1.5x, the equivalent focal length would be 75mm (50mm x 1.5).
Crop Sensor Lens Conversion
Another thing to keep in mind is that not all lenses are compatible with crop sensor cameras. If you are using a lens designed for a full-frame camera on a crop sensor camera, you may experience vignetting or other issues. Make sure to check the compatibility of your lenses with your crop sensor camera before using them.
35mm on Crop Sensor
One common question photographers have is whether they can use a 35mm lens on a crop camera. The answer is yes, but you need to take the crop factor into account. For example, if you have a crop factor of 1.5x, using a 35mm lens would be equivalent to using a 52.5mm lens on a full-frame camera.
Full-Frame Crop Factor
While crop factor is usually associated with crop sensor cameras, full-frame cameras also have a crop factor when using lenses designed for smaller sensors. For example, if you are using a lens designed for an APS-C sensor on a full-frame camera, you will experience a crop factor of approximately 1.5x.
Equivalent Focal Length or Effective Focal Length
One thing to keep in mind when using crop factor is equivalent focal length. Equivalent focal length is the focal length that would give you the same field of view on a full-frame camera as your current focal length on a crop sensor .
This is important to understand because it affects how you choose and use your lenses. For example, if you are used to shooting with a 50mm lens on a larger sensor full-frame camera, you would need to use a lens with an equivalent focal length of 75mm on a camera with a crop factor of 1.5x to achieve the same field of view.
Put another way, if you use the same lens (50mm) on one of your full frame cameras then shot the same photo at the same distance from your subject on a crop body camera, the image will look different. Even though it’s the same lens, scene and distance to subject, the crop factor gives it different equivalent focal lengths.
You can use this concept to your advantage to get extra reach out of a telephoto lens. For example, my 70-200mm f/2.8 lens on my full-frame has a max focal length of 200mm. But on my crop camera body (crop factor of 1.5), I now have a 300mm telephoto lens. I’ve increased the effective focal length of that lens by 1/3!
Finally, it’s worth noting that some lenses are designed specifically for crop sensor cameras. These lenses are often smaller and lighter than their full-frame counterparts, making them a great choice for travel or everyday use. If you are using a crop sensor , consider investing in a crop lens for the best performance.
Does the Crop Factor Affect Image Quality?
Crop factor itself does not affect image quality directly. However, it can have an indirect effect on image quality in certain situations.
For example, using a crop camera can result in a narrower field of view, which means that you may need to step back or zoom in more to capture a wider scene. This can make it more difficult to capture certain types of shots, such as landscapes or architecture. Additionally, since the image is being cropped in the camera, you may need to crop your images further in post-processing, which can result in a loss of image quality and resolution.
Another potential issue is that using a crop factor can amplify any flaws or imperfections in your lenses. This is because the smaller sensor of a crop camera magnifies the image produced by the lens, making any flaws or distortions more noticeable.
In conclusion, crop factor is an important concept to understand as a photographer, especially if you are using a crop sensor camera. By calculating the crop factor and understanding how it affects your lenses, you can get the most out of your equipment and create stunning images.