AF fine tuning (again)

tganiats

I have read through the past view years of comments on the topic and didn't see my question addressed.

The question of whether it is <<needed>> has been covered (with interesting comments about KR), but not whether it <<should be done>>. What's the difference? It might increase focus but create a pain in the a--. I write this because the D800 manual says, "AF tuning is not recommended in most situations and may interfere with normal focus; use only when required." So if Nikon doesn't recommend it, why? I assume people are not finding problems after AF fine-tuning, but I had to ask.

THANKS

spraynpray

I sent my D750 and D7100 back to Nikon with all my lenses and had them do a fine tune on both bodies with all the lenses I had at the time. The D750 and 24-120 were particularly poor together but Nikon transformed the lens with their fine-tune. I would say emphatically yes it is worthwhile as I just bought the Sigma 24-35 f2 and it is so far out that +20 doesn't get it even half way to right. At f2 even at three metres it is blurry as hell.

Whatever they recommend, a blurry picture is useless so what choice do you have?

Pistnbroke

All my lenses have required some fine tuning 18-140 minus 5 28-300 plus 15, Tamron 150-600 +10
and an old Tokina needed strips of shim under the mounting flange to get it to give a good auto focus picture !!!!
You will not create any problems only sharp pictures.

Spray....try your 24-35 at 35mm and f4 ..I often find the quality is so poor wide open on some lenses the band of sharpness is difficult to see

Ironheart

The reason they say that in the manual, is because you may for instance optimize the AF fine-tune for a close-up focus and wreck your focus at infinity, or vice-versa. If you have a lens that requires -15 to properly focus at inifinity, but needs a +10 to focus at minimum focus distance, you will drive yourself bat$h!t crazy, whereas at zero neither will be that bad, but neither will be great either.

If I had such a lens, I would send it (along with the camera) back to nikon for a tune-up. In fact, you can give them all of your lenses and bodies and have them "zero out" everything.

tganiats

Thanks to all!!!! I tried the 24-120. Had a -14 with FoCal... Noticeable difference. I'm happy. And the Forum is GREAT!

HipShot

@Pistnbroke What's the process to fine tune a 28-300mm zoom?

spraynpray

@HipShot: The procedure it box it up and send it to Nikon. Superzooms are best calibrated by them in my opinion as they can do multiple focal lengths.

Pistnbroke

I usually lay a 1m (39in) rule on the floor and put a pencil at 16inches sticking out sideways.. shoot from about 6 m at a low angel about 30deg and use AF-s focusing on the pencil.As you are using JPEG set sharp to +9 in picture control. I do it at 300mm where it is most critical. Sometimes shooting 1stop down is often better as graduations are sharper. Take shots at +20 +10 0 -10 -20 take the pic to your computer and zoom in and you will see the band of sharp ruler graduations ..the pencil should be in the middle...adjust to suit....you can re try at 150 and see if its different . With long lenses like the 150-600 tamron being 1or 2 out can make a big difference..I have a target with feathers at the end of the garden and I use that to find the best value...
If its a brand new lens check it again after a few hundred shots as they run in and it can change.
I have not sent one to Nikon because I cannot loose it for that long but if you cannot get it right Spraynpray is right send it back...keep the paperwork to boost its value when you sell it !!!!

HipShot

Thank you both.

KnockKnock

I found the old post on the previous iteration of NR in relation to the 50mm f/1.4 AF-S G. What was most revelatory is that focus moves back as you stop down, so the recommendation is to calibrate the f/1.4 lenses at f/2.8. If you calibrate at very near distances, very far can be thrown off. My 50mm wants -3 at very near focus, and +10 at very far. So I leave it at zero unless I'm working specifically in the near range. The 85mm f/1.8 AF-S seemed fine at all focal distances and apertures.

This is a huge feature opportunity for upper-models. Some sort of AF feedback auto-adjust, maybe by comparing a hybrid phase-detect sensor to nearby contrast-detect sensors for each AF actuation, so that no aperture or distance can throw AF off. It seems that even the difference between f/1.4 and f/1.8 makes a huge additional demand on AF accuracy. So if you never move off of kit lenses, it's probably irrelevant.

Pistnbroke

KnockKnock .....while all your points are valid I don't think people with less experience of fine focus adjust should be put off using it. There are vast improvements in image quality to be had with correct adjustment. Personally I shoot 97% of my work at F8 and most images are 20 ft away but the lens must focus where I want it to not 4 inches behind or in front.
At the other end of logic I don't even bother to focus my Samyang 14mm which is taped up at 10ft and F5.6 !!

Ironheart

@KnockKnock The issue of focus-shift has been with us as long as there has been SLRs; The lens is always metered and focused wide-open, and then stopped down for the snap. Some lenses are more affected than others. Personally I'd send that 50mm off to Nikon for an adjust. If you tend to shoot wide open, then calibrate wide open. If you always stop down, you should calibrate there.

BabaGanoush

@spraynpray: "The procedure it box it up and send it to Nikon. Superzooms are best calibrated by them in my opinion as they can do multiple focal lengths."

Not trying to start an argument, just want information...How do you know Nikon is able to adjust a zoom lens for multiple focal lengths, and how do they accomplish that? It sounds pretty tricky. If it works well, I might try sending in my D7200 for a "tuneup" as it's still under warranty (although the only lens I have that requires a substantial micro adjustment is the 18-140mm kit lens that came with the camera, in its case +12, but I almost always use the better behaved 16-80mm in its place).

spraynpray

Yes Baba, it is well documented here that Nikon can do things that we cannot when it comes to AF fine tune, and in your case if you send BOTH of your lenses along with your body to them and ask for AF fine tune, they will do it for free as your kit is under warranty. If you have any lenses that are out of warranty, they will still do them but for a small charge. They transformed my 24-120VR.

Pistnbroke

How do they do it ?? The lens contains a chip ( computer) and if you have a copy of the service software then the "look up table" the computer uses to tell it whats correct can be adjusted to match individual lenses. Very similar to the Sigma system but they wont sell you the dock or software. The lens is plugged into the camera and the computer linked via the USB socket on the camera

Ironheart

They can also make physical adjustments, if say, one of the lens groups is out of whack at a particular focal length.

BabaGanoush

Pistnbroke said:

How do they do it ?? The lens contains a chip ( computer) and if you have a copy of the service software then the "look up table" the computer uses to tell it whats correct can be adjusted to match individual lenses. Very similar to the Sigma system but they wont sell you the dock or software. The lens is plugged into the camera and the computer linked via the USB socket on the camera

Interesting. Thnx.

trolley

So, like the FoCal Pro system?

Pistnbroke

I don't think FoCal is changing the data in the lens chip like Nikon can or the sigma dock

Msmoto

As a general comment, the long lenses may need some fine tuning, particularly when the venues require shooting wide open. But I always fine tune at near infinity, or at least 10x the focal length. The use of a Nikon teleconverter, makes this mandatory IMO. There is minimal DOF when shooting wide open over 200mm, and often we want to have the sharp area at a specific point on our subject....i.e., race cars.

Generally I want the front windscreen or driver's helmet in focus, the front and rear can be a bit soft. This requires fine tuning, other wise the focus may be off 20cm or more even at a subject distance of 100 meters.

Ironheart

If you are shooting big lenses at medium to long distances, that is where you should fine tune. If you decide later to shoot a portrait with the same lens only a few feet away, you might need a different fine-tune value, depending on the lens. Unless your subjects appreciate a touch of "softness" +1 @Msmoto The use of a TC, and the additive effects of the tolerances of multiple physical mounts almost mandates a fine-tune.