nikon – AF tunes the first help

The first things first. The AF system of each camera is a little different. The shape and size of the actual sensitivity areas for each AF point do not have the same size and shape as the small squares in your viewfinder that represent them. They are usually much larger and are often not square or symmetrical, especially the peripherally located AF points, which are very often in the shape of "L" or "T".

Much of what is blamed for poor AF performance is due to an operator error. If the "focus point" in the viewfinder is placed on an indistinct target with very little contrast and another area of ​​higher contrast is in the total sensitivity area of ​​that AF point, the ## EQU1 ## The camera almost always locks on the higher contrast area. If this high contrast area is closer to or farther than our intended purpose, we are accusing the camera of focusing in the front or back!

In order to test and adjust the autofocus, we must make sure that our test setup is correct. The AF target should be flat and aligned parallel to the camera's sensor. The contrast should be high enough and far enough away from all inclined scales (often used to gauge how far and in which direction the AF adjustment needs to be adjusted) so that the camera does not try not to focus on anything other than the target correctly aligned. . If the target is tilted relative to the camera's sensor, your results will not be valid and will often make things worse.

Although this is not specific to Nikon, here is a summary in a blog entry of lensrentals.com by Joey Miller on the basics of autofocus adjustments. Of course, the specific menu instructions vary from camera to camera. You have therefore to consult the user manual of your Nikon D810 to know how to enter these settings.

1 – If you have entered an AF Tune Fine for each lens, the camera will recognize and store each lens when it is reconnected and use the amount of correction you have entered for that lens. The only time this may not be the case is if you have two copies of the same lens model or two lenses that report the same lens ID to the camera. Be aware that some third-party goals distort the identification of the purpose of a manufacturer's goal. Therefore, if one of your third-party goals tells your camera that it's the same model goal as one of your Nikon lenses (or another third-party lens). using the same goal identifier), he may not be able to distinguish each goal from the other. Some cameras with fine-tuning (Nikon), fine-tuning AF (Pentax) or micro-setting AF (Canon, Sony A-mount) can distinguish between multiple copies of the same lens and others not. You should consult your owner's manual to see if the D810 has this capability. You can check the EXIF ​​information of images shot with each lens to see how your camera identifies this lens.

2 – Keeping in touch is important, but it will have no effect on the precision of AF. Communication between cameras and lenses tends to be digital rather than analog. This could have an effect on whether or not AF is committed at all or not.

3 – Third party objectives tend to be less precise and more consistent in terms of AF performance than the manufacturer's objectives. This is especially the case when we compare the high-end lenses of the manufacturer to high-end third-party lenses. This is just a reality and it must be taken into account when deciding which objective to buy. When problems occur when using older third-party lenses on newer camera bodies, this usually means that a function (autofocus, control of the camera, etc.) is required. Opening, etc.) does not work. at all.

There are some other issues here that deal with different aspects of AF adjustment. Here are some examples that might be useful:

How to diagnose the source of the problem of focus in a camera?
Focal point causing blurred images?

Which offer of better results: FoCal or LensAlign Pro?
Do the sharpness problems that I face require a precise adjustment of the AF?
How can a lens cause an even focus on the front or back?
How can I focus more systematically on the point I want?
Why does my DSLR focus on the background rather than the subject when taking shallow DoF photos?
Canon or Tamron 70-200mm F2.8
How to fix the rear focus / front of my Canon 50mm F / 1.8 STM lens?