Achieving perfect focus has always been the Achilles Heal of DSLR’s, like many other photographers I have always relied on the fine-tuning lens system called Lens Align. Though a good product, it is not the easiest or quickest way to calibrate a lens. Step up the latest from Nikon to rectify this issue. Among the plethora of features introduced in Nikon’s new D5 and D500, I was particularly excited by automated AF Fine Tune feature. This feature promises photographers a way to quickly fine-tune their lenses, maximising sharpness and resolution, plus also avoiding the often-lengthy process of trial-and-error tuning with third party products.

DSLR’s often produce inconsistent focus whether it be front or back-focus, it is particularly evident with high speed primes. A lens issue may cause this but in the majority of cases it is due to the secondary phase-detect sensor under the mirror. DSLR’s are focus sensitive to misalignments in the secondary AF module, the image sensor and lens aberrations, to rectify this you need to apply calibration of the optics inside the module itself for best performance.

Camera/lens companies perform a lot of calibrations to make camera’s perfect but, calibrating every AF point at the factory is almost impossible. In reality tolerances are so fine in each unit that it is best off if you can calibrate your lens and body yourself. That’s where Nikon’s latest feature rules supreme, allowing fast aperture lenses to focus perfectly. This is a particularly exciting feature for me as two of my all time favourite lenses the Defocus Control 105 and 135mm f2 lenses, which are notoriously difficult to attain sharp focus now have a new lease of life. These two lenses are known to be some of the sharpest lenses ever made by Nikon but wide open often produced inconsistent results for many. Not now, with AF Fine Tune the brilliance of these two lenses can be revealed.

Nikon’s automated AF Fine Tune makes things easy by using contrast-detect AF in live view, by focusing using the image sensor, it is as accurate as you can get. Its a simple process to achieve perfect focus.

How To Set AF Fine Tune.

1. Setup the camera/lens on a tripod
2. Point the camera at a static object
3. Open Live View and set the focus point to the centre by pressing the centre button on the multi-selector
4. Focus on the subject in Live View, fine tune manually if required. For lens under 85mm use a 40x focal length, for 100 – 200mm use 30x the focal length. Example 24mm = 960mm/1m. 135mm = 4050mm/4.05m.
5. Depress the AF selector button and the movie record button at the same time for a few seconds till a dialog box appears on the rear screen
6. Confirm “YES” and the screen will display if the lens is calibrated, then confirm it is correct and press “OK”
7. Open up the Set Up menu and press the AF FINE TUNE to see what focus value the camera has set for the lens
8. Confirm that the AF Fine Tune setting for the particular lens is set on, and it is calibrated.
9. For perfect results do this several times to make sure it is accurate

ABOVE : Snap shots of the screens showing the lens and saved values.

With a little practice this calibration can be performed extremely quickly, even when on assignment in less than 20 seconds. With some lenses the optimal calibration value can change at different distances, though this may not necessarily always be the case, I suggest calibrating subjects at the distances you’re most likely to shoot with a particular lens. For a good all-round calibration, use a simple multiplication system, for lens under 85mm use a 40x focal length, for 100 – 200mm use 30x the focal length, this will be a good balance. This is just a suggestion, try several different distances to make sure you’re getting a consistent result.

As an example my two favourite lens, the DC 105 and 135mm f/2D lens the focus always seemed ok but setup on the D5 and its quite amazing the difference. The 105mm front focused and needed -18 of fine tune and the 135mm rear focused required +8 of fine tune calibration.

ABOVE: Before and after AF Fine Tune with the AF DC-Nikkor 135mm F/2D. The DC lenses are my all time favorite lenses but have always suffered from focus calibration, now with the D5/D500 this is issue has been resolved.

Nikon’s automated AF Fine Tune is truly one of the best features added to Nikon’s cameras in recent times, Automated Fine Tune is a game changer. It’s truly a useful feature that eliminates the guesswork and lengthy calibration process, allowing anyone to do it on the spot, anywhere, anytime with any lens. In particular it is ideal for working with shallow depth-of-field. Though this was conducted with the D5, and now just having received the D500, I’m happy to announce that it works equally as well on its smaller sibling.