Travel DIY · September 05, 2024

How Does the Camera Auto Focus Work and Why Sometimes It Fails? - Part II

Even with all the electronics and computing power in the camera there will always be scenarios where the camera auto focus fails. Failure can be when the camera can't focus and the picture is fuzzy or sometimes when the picture is actually in focus but the camera thinks that it is not. What causes such cases? The list is long but here are just a few examples:

Taking low light pictures

The passive auto focus system needs to see the picture in order to work and in low light scenarios this is not possible. Some systems use a series of flashes to overcome this limitation but this solution fails many times. An active system can measure the distance to the object in such scenarios but will fail if the object is not in the center of the picture or if there are a few objects at different distances.

Objects that tend to absorb the infrared beam they are using

Active systems can fail with objects that tend to absorb the infrared beam they are using. Some materials absorb infrared beams and will cause the active system to measure the wrong distance. In some scenarios other infrared sources such as candles and open flame fires can render the active system useless.

Low contrast objects such as white walls or blue skies

The passive auto focus relies on the fact that the Focus Level changes significantly when moving the lens back and forth. This allows the camera to settle on the right focus position. The Focus Level of low contrast objects does not change much and fails the passive system.

Knowing how the auto focus system works helps a photographer understand why sometimes the camera can not focus. In such scenarios the photographer can look for other solutions. Sometimes the photographer will have to use the manual focus. In other cases focusing on another object in the picture that is in the same distance but easier to focus on and locking the focus on that object will solve the problem.

Getting Started as a Traveling Photographer

Our eBook Getting Started as a Traveling Photographer is your ultimate guide to capturing stunning images on your adventures and learning how to sell them. Whether you're a beginner or an intermediate photographer, this eBook offers a clear, easy-to-follow approach to mastering both travel photography and the business side of selling your work.

Packed with expert tips and practical techniques, this highly-rated guide will help you elevate your photography skills, allowing you to confidently document every moment of your travels and turn those images into a profitable venture. Whether you're an enthusiastic traveler looking to improve your shots or aspiring to build a professional portfolio and sell your photographs, this eBook is the perfect companion for your journey into the world of travel photography and beyond.

I want to know more

Want to learn more?

Tags: Photography