Modern DSLR cameras are equipped with pretty advanced autofocus(AF) technology. Knowing how to use the autofocus on your DSLR camera will ensure you capture quality, sharp photographs every time.
Autofocus(AF) is one feature that has just gotten better with the advancement of cameras. So, what is AF all about and why do you care?
Table of Contents
- What Does AF Mean On Camera?
- How Many AF Points Do You Need?
- Do I Need Autofocus For Video?
- In Summary
There’s not much worse than getting what you think are some great shots and realizing later these images are not quite in focus. I ran into this issue when I started wearing glasses.
I enjoyed using my DSLR camera’s manual focus for a lot of my shots. I thought my pictures were in focus only to see later I had made a mistake. So, I wanted to understand more about the various AF settings my Nikon offered.
This article discusses autofocus in general instead of focusing(see what I did there) on a particular brand’s setup.
If I’m being honest, I frequently reflect on and miss my old manual film camera. It was simple and straightforward to use. Even so, it’s hard not to like all the bells and whistles of today’s mini-computer like DSLR cameras.
The autofocus options are features that can be confusing to many photographers so we’ll talk about them below.
What Does AF Mean On Camera?
As we’ve said, AF stands for autofocus. DSLR cameras have several AF options for you to choose from because the camera itself doesn’t know what subject you want to be in focus on. DSLR cameras look for contrast differences to obtain sharpness or image focus.
There are two ways the camera obtains this contrast information, by using either Phase Detection AF or Contrast Detection AF.
Phase Detection AF
Phase Detection is used by the camera when looking through the optical viewfinder. Using the camera’s sensors, it splits the image into two and compares them, to see if they are in “phase”.
Phase Detection examines how out of focus the image is and makes adjustments until the image is sharp or “in-phase”. This process is fast and useful for taking action or moving subjects.
Contrast Detection AF
Contrast Detection is used by the DSLR camera when using LCD Live View mode. It works by trying to achieve contrast between edges in an image. That is if there is high contrast the image should be in focus.
This process is slower than Phase Detection but is very accurate if there is enough light.
How Many AF Points Do You Need?
Focus points are the small squares or dots that you can see in the optical viewfinder. DSLR cameras vary in how many focus points they contain. Phase Detection uses these focus points via the sensors to obtain perfect focus.
So, is it better to have more focus points on your camera? The short answer is yes, it’s advantageous to have more focal data input for the camera. But really the answer is it depends on you and how you intend to use your DSLR.
If you’re taking stills or say portraits, it won’t make much difference in the number of focus points. It will come into play more if you wish to take action or sports-type pictures.
Don’t make the number of AF points the deciding factor when trying to choose between two cameras. Focus on the DSLR’s low-light ability and other functions important to you.
Do I Need Autofocus For Video?
Unless you are a professional, you will probably want to use continuous autofocus on your DSLR camera for videos. The camera’s microphone might pick up the noise though, if so, consider using a remote microphone.
If you are filming actions or moving subjects the autofocus will be helpful. If your video contains a still subject, it might be better to manually focus on the subject.
The number of autofocus or AF points is an important consideration when selecting a DSLR camera, but should not be the deciding factor. Instead, think about how you will use the camera and go out and try several brands. Get a feel of them, check their options, menu settings, etc. If you plan on shooting live-action or sports, autofocus will be more of a consideration, but examine how well it performs in low light.
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