Camera and Lens Calibration
Camera and Lens Calibration
Why do you need lens calibration?
How do you know if your lenses need calibrating?
Well this is relatively easy. If you zoom in on a picture on the back of your camera (though this has to be where your focus point is), you might notice that the picture is sharper behind or in front of your subject/focus point. This is called front or back focusing, depending on where the picture is sharpest. This is common enough, but it can make or break your pictures. One of our customers, a photographer who had recently been to Namibia went through her photos at the end of the day only to find most of her photos were unusable. It was absolutely gutting for her because she had spent all day at a water hole in Etosha photographing Lilac-breasted Rollers, and all her pictures were focused about 10 inches in front of her subject…no pin sharp eye and a whole lot of unusable images!
The chance of getting a perfect lens from the manufacture is highly unlikely, and no two lenses perform the same. These performance pitfalls are known as tolerances. In terms of AF adjustment, Canon’s tolerances are plus/minus 5, Nikon’s are plus/minus 10 and Sigma and Tamron are around plus/minus 15. Additionally, imperfections can also exist within the camera’s focus sensor (positioned beneath the mirror mechanism) where improper seating of the sensor will produce problems of its own in regard to back and front focusing. In reality, the likelihood of having a camera setup with back and front focus issues is highly likely. It’s a shame that such tolerances exist, but in such specific optical science, individual lenses are bound to have imperfections when they are produced in such large batches.
How Camera and Lens Calibration Works…
As mentioned above, cameras front and back focusing is a major player in why you aren’t getting sharp images. Luckily for us, most cameras have a setting which allows for compensating back or front focusing lenses. This is called AF Fine Tune in Nikon and AF Micro adjustment in Canon. Calibration is used to compensate for anomalies in the autofocus sensor, and since most mirrorless cameras focus directly on the imaging sensor, there is no need to calibrate these systems. There are some exceptions to this though….Nikon Z7 for example and Sony A7
This compensation can be performed in small incremental steps (typically between -20 to 0 and then to +20). Putting in a negative figure will move the point of focus closer to the camera, and dialling a positive number will move the focused point away from the camera. This effectively tells the focus system to aim at where it would normally focus, except slightly move the focused point away or towards the camera.
An important thing to keep in mind however, is that calibration is camera and lens specific. So, if you have multiple cameras and lenses, you have to calibrate each lens on each camera, Additionally, you might need to periodically re-calibrate your camera gear and many professionals do it as often as twice a year!
One important thing for us bird photographers to take into account, is when using tele-converters, the focus issues are magnified umpteen times. Also, 3rd party lenses are known to be really bad for it, so it’s worth checking it on your camera if you have a Sigma or Tamron lens.
Camera and Lens Calibration Methods
DIY Camera and Lens Calibration:
This is basically buying a focus card and tweaking the micro adjustments in your camera settings until you have the best result
Manual lens calibration:
A number of camera shops, camera repair agents and even some companies ‘specialising’ in calibration use a manual process of ‘shunting’. A slightly more methodical approach to DIY lens calibration but nowhere near as accurate as the software driven method. Where this method is of great advantage is when the lens needs a huge adjustment. Typically over + or – 20. With such a big adjustment is necessary to shimmy a glass element until within range of a finer more accurate calibration. Work is done on both the camera body – adjusting the seating of the sensor to compensate for extreme problems in the camera and the lenses separately. A light is shone through the lens onto a targeted grid and then the lens is adjusted for pitch or yaw (this is know as “shimming”) This is only available for Canon L lenses.
Software driven lens calibration:
There are a number of software solutions for lens calibration on the market but there is one clear market leader who have maintained that position for many years by driving development in additional functionality as well as keeping up to date with the exceedingly fast launch speeds of new models by the camera manufacturers. Focal by Reikan.
Which Cameras Can Be Calibrated?
In short any Canon and Nikon camera that support autofocus micro adjustment or autofocus fine tune. That said when a new model is released the is significant testing and updating of software to ensure the camera and lens calibration process can be performed accurately.
Which Lenses Can Be Calibrated?
There is only one group of lenses that can’t be calibrated. The tilt and shift lens, which are the Canon TSE range and the Nikon PC range. Apart from that pretty much all Canon and Nikon lenses can be calibrated. For third party lenses like Sigma and Tamron the coverage is less but does include key lenses and newer releases.
Camera and Lens Calibration Results