Join Chris Orwig for an in-depth discussion in this video How sensor size affects focal length, part of Exploring Photography: Finding the Perfect Portrait Lens.
In the previous movie, we talked about focal length really in general terms. Here I want to get a little bit more specific, and I want to talk about how sensor size actually affects our focal length. Here I have an old camera, which I took apart, that was a lot fun to do that, and I pulled out the sensor. And here we can see the sensor size, which is a rectangle, and this particular sensor is APSC. Now, what does that mean and how does that actually effect focal length? Well, here I have a few cardboards illustrating different sensor sizes.
This one over here is full frame. If we're shooting with a normal focal length, let's say a 50 mm lens, well, on a full frame camera, it's 50, but if we're using something different, that focal length is going to change because of what's called a crop factor. If we have APSC, it's actually going to be longer than a 50. It will move all the way up to a 75. If we're using the camera, maybe, which is micro four thirds, it has a two times crop factor. So, that 50 mm lens, well, it become a 100. There are other scenarios, as well.
Maybe you have a camera like this one here, which has one lens on it. You can't change it. What you can do is, you can look up to your camera and lens to discover what its focal length is. One of the more common cameras in the world is the smart phone. The focal length lens of these typically is right around 30 mm. And what you want to do is really get familiar with what the focal length is that you're using. So, when you're using this, you're saying, you know what, I'm using a wide-angle lens. And when you're creating portraits with a wide-angle lens, there are certain things to keep in mind.
What I recommend you do, is that you look up what camera you have and what sensor it has, and figure out that crop factor. So, if you're working maybe with an APSC sensor and a 50 mm lens, in your mind, you now know this is 75. What I like to do with these, especially when I'm teaching, is to have people get some painter's tape, and to get a little piece of tape here and then to stick it on the lens, and to right the focal length that it is, the equivalent. In this case, this 50 has now become a 75.
And just keep it on for a week or two, but that will give you this familiarity with what it actually is, which is really important in portraiture. Because in this course, we'll look at, remember, those different groups of focal lengths. And the more familiarity we have with what we're shooting, well, the better photographs that we'll be able to create
- How sensor size affects focal length
- Shooting with different focal lengths
- Shooting at the best angle for your lens
- Understanding how f-stop, focal length, and camera distance affect depth of field
- Finding a great lens at an affordable price