In general, the essence of this article is Lens Calibration or lens calibration. If you find that the case of soft lesions is very far compared to when the stop down to 1 f-stop, then the AF calibration should be done. If you currently have very sharp results in the largest openings, then this article can be scanned.
Miss Focus Factor
From a number of experiences that have been, the factors that are often the cause of the auto-focus misses are the following:
- These affordable lenses are produced thousands of times, in addition to saving costs, it is targeting prosumer or non-pro photographers, all of them definitely like 50mm f1.8, right? … right. This is what makes quality control, especially mechanical focus on lenses of this type not as tight as Canon L or Nikon Gold Ring lenses.
- AF mechanical system on the body, so it’s not just the lens that makes the focus miss, it could be your body that actually makes the X miss focus lens. For crossing factors no. 1 and 2 it is a good idea to exchange lenses and cameras with each other and test them with friends, if necessary and if there is time.
- A used lens, which we don’t know has ever fallen to the floor, hit a wall? or have been washed because of fungus
- Too late pressing the shutter when the subject turns out to be moving / moving in a coordinate z axis (depth, back and forth), understand, even the subject retreating just 1cm of natural movement is already out of sharp space when you use a very large f with close subject distance.
AF Tune / AF Micro adjustment
In the example in this article, I used the Nikon D700 body. This focus tuning feature is basically the same in function, only the names that sound different.
- Nikon D7000 / 7100, D300, D600, D700, D3, D4
- Canon 50D, 7D, 6D, 5D, 1D
It should be noted earlier, that both modern AF lenses and modern DSLR bodies have CPUs that interact with each other. So every time we do a calibration on lens A, it will automatically save presets for lens A.
What is needed is Lens Align as shown below
The following is a very short tutorial in point flow:
- Our D700 camera is set on a tripod (yes, it must be a tripod because we are going to do an image comparison)
- Setting (conditioning) ISO 3200, 1/25
- The coincidence lens is a 24mm f / 2.8 old school AF lens, buy 2nd hand how many times this is a clear miss focus on the biggest aperture, so our lens is set f2.8
- Make the subject pattern lined up at least 2 positions front and back, it’s good to be closer together, imagine you put the property like the Lens Align image above
- Aim for consistent focus on the most contrasting subjects
- The default AF Tune is 0, if you don’t feel it sharp, do an extreme tune to +10 or -10, to determine whether this is front focusing or back focusing
- Snap, zoom 100%, observe and feel … or if you want to definitely check on a computer with a bigger screen, do it again
- If you have found the character missed, do precision tune slowly until it can be the sharpest, the body gives room tuning -20 to +20
- Already sharp ? Enjoy, your lens seems to be reborn