Razor-Sharp Autofocus – A Simple Guide To Calibrating Your Lenses
When you finally make the decision and get an expensive lens, you expect them to be perfect. But unfortunately, regardless of how good the lens is, there always exists minor differences when attached to the camera. You may have noticed that your photographs never look as impressive as those you see on the internet.
The camera bodies and lens are made at different times and in different settings and when you bring the two together, there are minor adjustments which you will need to make to make sure you get the best possible image quality from the lens. There is a minor error that exists when the camera and the lens work together in the autofocus method. Though the error varies from lens to lens, there exists the error in every single lens.
So, whether your lens and camera are old or new, fine-tuning the lens to the camera body is crucial. In this guide, we discuss how to calibrate your lenses to achieve razor-sharp autofocus and image quality.
What you Need
To calibrate the autofocus on your camera to the lens, you need the following things:
Set the camera and the tripod at the same height as the focus chart and level the camera.
Setting Up the Chart
The next step is setting up the focus chart. You can either download and get a print of one of the focus charts available online or use something like a metal ruler or a packaging with a lot of text on it.
Arrange the focus chart at such an angle that lets you easily identify the focus dropping off. Find a particular point to focus on and then the areas around it to see where the focus is actually falling. When using a ruler, you can focus on a particular measurement and check what around it is in or out of focus. You can mount the ruler on a stand at a down-facing angle and focus the camera in the middle of it.
Setting up the Camera and Tripod
Now, you will need to make adjustments to the camera setup and settings. Firstly, place the camera and the lens at a suitable distance from the focus chart. The distance depends on the focal length of the lens you are calibrating and you can use a handy LensAlign chart to calculate the optimum distance for the test. The Distance Tool lets you input details like focal length, sensor size, minimum aperture to suggest the distance. Set up the camera on the tripod at the recommended distance.
You need to set the aperture to the minimum your lens allows. Also, make sure sufficient lighting is available and you shoot at a high shutter speed to be able to click a crisp image and avoid any minor movement affecting the focus adjustment.
Now, switch the camera to turn on the Live-View mode. In this mode, enlarge the picture with the use of the Magnify button. See that you get the finest details of your focus chart in the focus and take a shot. Take 3 or more shots to have a proper view of the autofocus. You can defocus each time and take the shot again to check your autofocus well.
Checking the Images
Now you can import the photographs into some editing software such as Capture One or Lightroom. Importing the images allows zooming in further. The JPEG images you see on the camera’s back appear fuzzy on zooming in a lot whereas importing the photos into a software lets you test your autofocus precisely. Once you import the pictures, use the zoom function in such a way that the focus fills the entire frame. This is when you can see if any adjustment needs to be done to the autofocus.
If the images you see are razor sharp, you can deduce that you have got a great lens that needs no calibration. If this is not the case, you can read further and proceed.
Go to the menu with a spanner icon and you can find the option for fine-tuning at the bottom. From there, enable the AF Fine-Tune. Once the option is enabled, you can start making some adjustments. When you review the images and find that the camera’s autofocus is constantly missing the mark, you can go for the corrections.
If the autofocus is continually focusing behind your aimed focal point, you should adjust the fine tune negatively and get the focus where it needs to be. Alternately, if the autofocus is focusing in front of the focal point desired, you can increase the fine tune positively to get it right.
The adjustments might take a series of attempts to get the desired result and you can start with the large changes to see the effect. You can make the fine tune correction and capture some more images. Review them in the software and make other corrections. You can repeat the steps until you are satisfied with the results.
This guide helps you get sharper auto-focus clicks to be able to achieve razor-sharp images on your camera. However, this process does not make your lens sharper. If you want to test how sharp your lens is, you can use live-view, zoom in to the maximum and take manual focus shots.
Once you calibrate the lenses and camera, you are ready to enjoy the sharpness and crispness of your photographs.