TriX Loc: Raleigh, NC

Exactly.

DavidPine Loc: Fredericksburg, TX

The best way is to have it professionally (electronically) calibrated. It doesn't cost that much. If you are interested in the 500mm focal length let them know that's what you want.

tcthome Loc: NJ

Test it. If it is out of focus, you may need to use the Auto Fine Tune. Your camera manual will tell you how to do a fine tune if needed.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

It's very easy to tell if a lens is out of whack. I test, and if there is an error, and there have been in the past, the lens and/or camera go in for repair once I determine where the problem is. Then I test again.

BTW, you do realize that any kind of tuning, AF Fine tuning or factory adjustment, will only ever get you really close to the ideal, but never 100%. The goal is to be within a margin of error of accurate focus. If you take 100 pictures of the same still target, there will be a few that are not going to be in perfect focus. That's the nature of mechanical systems. They are rarely 100% accurate.

Regardless, Nikon, Canon, Olympus and possibly others guidance on AF Fine tune is remarkably similar - none recommend it as a permanent solution. And AF-Fine tune must be done at the most used focal length and distance. The more long term solution is proper factory measurement and calibration, using an optical bench. Sorry, I don't mean to dismiss or diminish your credentials, but when the Mfgrs are contradicting what you are saying, I will tend to go with the Mfgrs. And yes, if you have a lens that requires +20 adjustment, it may not focus at infinity, especially if the lens at infinity requires only a +5.

I am glad your system is working for you, but it didn't work for me, which is why my gear does a great job, everything is tack sharp - regardless of what body is used with what lens, and when there is a problem it is addressed to keep it that way. Is it 100% accurate? Nope. But it will almost always be closer across a bunch of cameras and lenses than the AF-Fine tune solution. And this comes from dealing with digital AF systems since 2004 (D70) and speaking with Nikon's techs in Melville on multiple occasions.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

The last time I had an issue with a camera was a demo d800 I bought directly from Nikon. It had 5 shutter actuations. I took it to an airshow, along with my other D800. As it turned out 75% of the images I took with my 600mmF4 on that body were soft - by a lot. I tried a few other lenses and they all seemed to have an issue on the body. So it was pretty clear that the body was malfunctioning. These lenses were all fine on my other cameras. The longer the focal length the more obvious the problem. First thing Monday morning I was at Nikon in Melville with both the 600 and the D800, to illustrate the problem. They agreed. I went home. Later that afternoon they told me that they would need to adjust the lens AND the camera. I emphatically said NO! The body could not focus with lenses that were fine on other bodies. If they adjusted the lens, I would have a problem with the other bodies. So no. They called me the following day and told me it was fixed. I asked what they did - and the person calling me could not explain what was done. I took an 80-200 with me to check, along with my other D800. They didn't fix the problem, though the body had a pretty big offset dialed in for that 600mm so it sorta looked ok. When I put the 80-200 it was like it was before I gave it to them.

So I repeated that they needed to repair the body or I needed to get my money back. A couple of days later they called and said it was fixed. I rolled my eyes and jumped in the car with my working D800 and the 80-200. This time I could not detect any differences between the bodies. They wrote on the invoice that they adjusted "communication parameters" between the lens and the camera, inside the camera. All I know is that I still have this camer 5 yrs later and it is still producing crisp and sharp images with all of my lenses. I tend to use my long lenses at distances ranging from minimum focus distance to 800 ft.

This was taken with the repaired camera and a 600mmF4 with a 1.4X TC, at a range of around 800 ft, uncropped and cropped. No AF fine tune compensation, just well-executed factory calibration on lens (when I first acquired it) and the body.

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TriX Loc: Raleigh, NC

Only one way to really tell what method is best - Focal or service center cal. Take a lens that needs calibration. Cal with Focal and test for acuity at various distances including infinity. Use Focal or other tool to measure acuity at the various distances. Reset to zero MFA, send to service center for cal and then redo the test at various distances and infinity. Compare the results.

I have actually done this test with a Canon 85mm Lens I purchased directly from Canon. Tested, and it required +12 MFA to bring it into calibration at the suggested cal distance. Checked it at distances from 5’ to infinity and recorded the suggested calibration at each distance - varied from +10 to +13 depending on distance (so off a max of 3 points worst case, but still 9 points better than uncalibrated) and focused at infinity. I wasn’t satisfied because it required so much correction. Since I had just purchased it from Canon, I sent it in for calibration. Received a call that it was within factory specs. Spoke to a supervisor who stated that it was within specs and they could do nothing else. In the end, I took it back, returned it to +12 and have been using it ever since and according to the measured acuity (with Focal), it is quite sharp and AF very good compared to my other lenses. If I had not been able to use MFA, I would have returned the lens. Maybe Nikon service is different from Canon, but both the body and the lens were within specs and the service center could not do as good a job as Focal. Just one experience but…I did not send them both the camera and the lens, so no idea if they could have improved it further, but every time you ship instruments of any kind, there’s always the opportunity for shock to make it worse, and then there’s the cost and inconvenience. And what if they actually adjusted both and now the camera was off with other lenses. Seems to me that a custom calibration with each lens is the only way to avoid that, and Focal accomplishes that unless you’re willing to live with the standard factory tolerances and stack up. So for me, the question is do you want to tolerate the within factory spec error or the Focal correction per distance error. My opinion is that the latter is most accurate from my testing.

And finally, for those that have always used their lenses out of the box and gotten acceptable results, my question is: could it have been better, or is good enough adequate? For me, having spent a good piece of my working career in precision measurements and instruments, “good enough” or “acceptable” is not acceptable to me - I want it as close to 100% right as possible, hence my views on calibration.

Personally, I KNOW that proper calibration can improve AF accuracy for many/most lenses on DSLRs - I’ve tested it too many times not to believe that. The open question is it better to do it yourself using good tools or send it to a factory service center?