Back Focusing a Camera Is an Auto-Focus Fault
Back focusing occurs when the camera or lens autofocuses slightly in front of or behind where it should be.
Photographers often struggle with this issue, which may not be apparent to casual observers. While landscape and architecture photographers don’t usually have much to worry about, portrait, commercial and wildlife photographers can face serious difficulties due to lack of awareness.
1. Auto-Focus Fault
Back Focusing a Camera is when the camera and lens are not communicating properly. This can happen with fast aperture lenses due to various reasons, such as improper technique or an incorrect subject.
Most modern cameras feature an autofocus calibration or focus micro-adjustment menu function that can help correct this problem. Unfortunately, it may not always solve the issue and in some cases you may need to take your camera or lens into a service center for repair.
Many photographers have experienced difficulty focusing their cameras’ autofocus when shooting in dim lighting environments, particularly if the subject is not highly contrasting in color, such as a dark blue sky or white wall.
Test for backfocus issues by pressing the dedicated button on your camera’s back near the shutter release. Most modern DSLR cameras feature this feature and you’ll likely locate it near the lens release on the back.
To conduct this test, you will need a tripod, your camera and lens that you suspect may have issues with focus. Additionally, five AA batteries should be placed flat on a surface at an angle of 45 degrees from the film plane as well as a focus test card.
Try this test several times with different lenses to see if the focus problem persists. This can be very useful in identifying whether the issue lies with the lens or camera body.
One of the primary causes for back focusing is poor lens calibration. This can occur when installing a new lens or damage has occurred to an old one.
Dirty lens contacts can also contribute to this problem, as when these contacts become dirty they cannot communicate effectively with the camera and focus becomes inconsistent.
To resolve this problem, ensure your lens is stored and handled appropriately. This can be achieved by keeping it in a proper case or regularly cleaning it. Taking proper care of your lens can help avoid this type of issue from arising in the first place, so it’s worth giving this a try!
2. Test With A Focus Chart
Focus charts are an invaluable tool for testing your lens and camera’s focus. Not only can this determine whether the focus on your lens is front or back focused, but it also allows you to check the sharpness of photos within their frame.
Home focus charts can easily be created with a ruler and yardstick. This convenient device allows you to test your lenses’ focus accuracy, then make necessary adjustments to your camera’s settings to resolve any issues.
First, set up your test chart in a location where the camera can easily see it when taking pictures. For best results, hang it across from the camera on a vertical wall.
Next, place two rulers on either side of the focus chart. These should be parallel to one another and touching at exactly the same measurement on the focus chart so you can clearly view them through your viewfinder.
Once you have done this, take a picture to ensure the middle of your focus chart is in focus and compare it with what appears in your viewfinder. If the picture is not sharp as expected, your lens might be set for front or back focusing; this must be corrected before taking further photographs.
If your lens is not focusing correctly, you can use the auto-focus fine tune feature of your camera to correct the issue. This facility is common on modern cameras and provides a simple solution for any lens focusing issues you may experience.
Once your focus has been corrected, you can attempt taking more pictures and see if your lens becomes sharp again. If so, congratulations – now it’s time to take your photography seriously again!
Testing your lens’ back or front focus is easy with a focus chart. These charts can be found at various locations and used to evaluate different lenses. The ideal focus charts fill the whole frame of your camera, allowing you to observe how sharpness varies throughout each shot.
3. Calibrating A Camera With Back Focusing
One of the primary causes of blurry photos is focus issues. If your camera’s autofocus system is malfunctioning, it may not be focusing as accurately as desired. Usually, this issue can be remedied with a simple adjustment in settings.
Though autofocus on cameras is designed for accuracy, it does have some error tolerance – especially with more modern models and lenses. This could explain why certain combinations of lens and camera may appear slightly off even though they were made by the same manufacturer.
Photographers often end up with blurry photos when their camera attempts to focus on an object that is out of focus – or, in some cases, front focusing (the focus falls behind the subject of the photo) instead of back focusing (focus falls in front of subject).
To correct these errors, calibrating the autofocus on your camera will allow it to compensate. Do this by dialing a number into the focus point; negative numbers will compensate for back focusing while positive ones will compensate for front focusing.
Once you enter a number into the camera, it will store it in memory and use it whenever that lens is attached to your camera. This feature is essential as it guarantees sharp photos every time.
Calibration your camera is easy with LensAlign, a cheap and simple device that makes the process effortless. While not as precise as full automated calibration software such as Reikan FoCal, LensAlign still does its job well enough to give you some assurance that your photos are sharp and focused.
To conduct the test, you’ll need a well-lit environment, a tripod and something to use as your calibration subject – such as a book, focus chart or ruler with markings on it.
Once your item is in focus, take a few photos to confirm the focus is as desired. If not, turn on autofocus again and take another shot ensuring your subject is centered within the center of the book or chart and compare this with how the camera sees the image. If your final photograph still looks back focused, this indicates that calibration of your lens may be needed.
4. Can Back Focusing on a Camera or Lens Be Repaired?
Back focusing is the term used to describe when a camera or lens focuses in front of or behind the subject instead of where it should have. This can be an irritating issue for photographers, particularly when shooting with large apertures.
In some instances, back focusing can be corrected using the focus adjustment settings on your camera’s autofocus system. Unfortunately, this solution may not always be possible.
The primary cause of this issue is that many DSLR and SLT cameras are constructed so that the mirror and autofocus sensor are separate components. As a result, light hitting the mirror bounces off one side before reaching the autofocus sensor, leading to incorrect focusing.
To correct this problem, use your camera’s autofocus calibration feature to adjust the position of the mirror and sensor. This will automatically adjust all autofocus settings accordingly.
You could also try taking your camera to a service center to resolve the problem. This works best if both items are from the same manufacturer, as they will know exactly what to do.
Another option is to have your lens and camera calibrated – this can be achieved using a focus chart or special tools such as Datacolor LensCal. Doing this will align both components on the correct focusing spot, making it simpler for them to focus accurately.
Modern DSLRs and SLTs typically have autofocus adjustments built-in, making testing and tweaking the settings relatively straightforward. Unfortunately, accuracy in performing this process may be required in order to correct any back focusing issues you might encounter.
