cmikal

I recently got the Nikon D500. I shot with it for a few weeks without using the auto-focus fine tuning feature that Nikon included on this camera. (I took it out of the box, attached a lens and started shooting). Today, I decide to try the "auto-fine tune focus feature". I tested it on both photo test patterns and normal stuff around the yard that had nice distinct edges, boundaries, and contrast. I set the camera on a tripod in a bright, sunny location and did multiple tests from the same camera position shooting at the same subject. I refocused using auto-focus after each test.

The results that I got surprised me to the point where I finally decided that this feature is probably worthless. Here are the results for one series of test shot at the same target from the same distance using the same lens. The camera's adjustment range is +/-20:
+4
+15
+8
+16
+16
+12
+11
+15
+4
+19

All of these fall on the "+" side of the range. In other tests, I got a few that fell on the negative side, but only by -1 or -2. My only conclusion as far as making any permanent adjustments with this camera/lens combinbation is that perhaps I could improve focus a bit by setting it to approximately +12, which is the average of all those readings. If I added up all the readings from every test, including the ones I didn't show here, the number would be lower, but still on the plus side of "0".

So....I have several observations. First, the fine tuning feature on this camera is probably worthless in practical terms. Second, if you only run this fine tune function once and begin shooting as if you just made things better, you may have just made things much much worse. Third, even if I could get the focus dialed in a bit closer than the default "0" value, doing so may still be a useless exercise because the auto-focus system on this camera with this lens combination would still have a likelihood of missing pin point focus on each and every shutter click by approximately 7 or 8 units above and below whatever value I set. The last observation is that my seemingly variable results might be due to the lens that I am using. Maybe a worn gear. Maybe just a bad implementation of the focus mechanism in the lens brand or lens type. etc etc.... Unfortunately, I don't have an unlimited budget to buy several of the best lenses made to run a baseline test to see how much to blame on the camera and how much to blame on the lens.

Thoughts? Comments?

OddJobber Loc: Portland, OR

What lens did you use?

imagemeister Loc: mid east Florida

What lens are we talking about ??

cmikal

For the results in my original post, A Tamron AF 17-50 (IF) f2.8 without VC. Tamron # A16

OddJobber Loc: Portland, OR

f.8?

cmikal

Sorry. 17-50 f2.8. without VC. I think I need to change the batteries in my keyboard. I am getting a lot of double keystrokes or no keystrokes when I hit a key. I fixed them, so the lens info makes more sense

cmikal

I took the time to try another lens. This is a kit lens Nikon 18-140 f3.5-5.6

My results were considerably less variable than with my Tamron. There was a 5 point spread from 0 to +5. I guess one of the possibilities for the tighter grouping is that the 18-140mm that I own has seen much less use than the Tamron, so probably much less internal wear. If wear isn't one of the issues, then their is something else going, but the difference between the 2 lenses in terms of micro-focus variance is observable. If I had more lens examples to put on this camera I would try them too, but I don't. My other lenses are 100% manual focus.

I'm curious about other peoples results and their thoughts on this camera feature.

mwsilvers Loc: Central New Jersey

Just a couple of thoughts. First the process may be optimized to work better with Nikkor lenses, and second, I believe on the D500 only a single correction is made per lens, regardless of whether its a prime or a zoom lens. Is that correct? On Canon cameras when adjusting zooms lenses you can make two adjustments. One for the wide end and one for the long end, and even that is somewhat of a compromise, but a single adjustment for a zoom lens is probably not going to be spot on at all focal lengths. They may refine the process over time, and the automated aspect of it is very intriguing, but from my point of view Sigma zoom lenses with 16 different settings via the USB dock is more likely to give you consistently accurate results. The down side of using the dock is the process is very arduous and time consuming, and of course it won'r work with your older Sigma lens.

cmikal

I'm not sure about optimization for Nikon/Nikkor vs other brands. If that turns out to be true, I missed that caveat in the Nikon literature.

Regarding various focal lengths, I agree that the adjustment is potentially (probably) different at different focal lengths, But that would also be the case for an unadjusted lens/camera pair where you just put the lens on and shoot without attempting micro adjustment. I didn't test different focal lengths to see if there were differences. The 15 to 20 point swing at the first focal length stopped me in my tracks. If I had gotten reasonable consistency test after test at the first focal length, I would have moved on to another focal length and maybe test both extremes and something in the middle.

What I think is happening is that my Tamron is old with internal wear and maybe the focusing system isn't as accurate or consistent as a newer generation lens might be. If that's the case, it tells me that it's time for a brand new lens or a modern vintage lens with minimal mileage on it. Perhaps this auto-tune process is good for more than fine tuning your lenses for sharper pics. Perhaps it can give an indication that your old lenses need to be retired due to internal wear and other effects of aging. Minimal swing in multiple test results > all is well. Big swing in multiple test results > time to get a new lens.

mwsilvers Loc: Central New Jersey

You are assuming the need for adjustment is identical across a zoom lenses focal range, and that is not always true and can vary significantly depending on the camera its mounted on. Having two Sigma lenses and 3 Canon bodies I have a lot of first hand experience with using those lenses and the USB dock on these three cameras. The capability for 16 different adjustments makes a huge difference.

MW

I used FoCal, an external software app running under Windows to do this and would get much more consistent results than what you report. It is NOT a quick process, hence I suspect that the internal processor on your D500 just doesn't have the muscle to do the job. With FoCal I shot before and after tests and the effort was well worth while. So don't give up on the idea but consider that there may be better ways to accomplish it.

Additional thought: Didn't you post that you were do I get the fine tune with a Tamron? It is possible that there is an issue with body to lens communication such that focus is inconsistent. AF fine tune won't be much help unless the gocus error is consistent shot to shot.

cmikal

My first tests were with an old non-VC Tamron. After the puzzling results with the Tamron, I re-tested with a Nikon 18-140, which produced consistent results with minimal deviation.

I'm not sure that I'll ever know exactly why the Tamron has such a wide array of results, but it's obvious the inconsistency is there. Maybe the lens has degraded somehow over time and thats as good as it gets for that lens. Maybe the Tamron is fine and the lens and D500 don't play well together so the Tamron is saying "1" and the camera says "huh", and just picks a random number. IDK, but since I can get acceptable and repeatable results with the Nikon lens, I think I'm going through the process correctly. It might be time to turn the Tamron into a paperweight.

mongoose777 Loc: Frisco Texas

I personally would not go +/- 4 either way.
I do not trust it enough.
I have 6 camera bodies and never auto tune anything as all the shots
are extremely sharp enough for my use.
However, I have sent in a couple of lens to Nikon for calibration because
the sharpness may be average due to accidental banging around while shooting.
The lens that are serviced by NPS will comes back extremely sharp.
All my lens are sharp enough out to the box, I just feel the Auto Tuning
can potentially be overused and can create more issues
than needed.

MW

When I used FoCal, the instructions address this. They suggest either optimize for the most commonly used focal length or to a focal length equal to about 3/4 of the maximum zoom. At least in my the later was excellent advise. I ran the program for several focal lengths and plotted the results. The 3/4 tended to minimize the average error. Also I noticed thaT a plot of the errors would alway either decrease or increase continuously over the zoom range- no wobbly up-down plots. All lenses were Nikon. Someone else could obviously have different results.

While I don't need FoCal any more (switched to mirrorless), I can recommend it if you don't mind the cost. The results were always much more repeatable than with any other method which for me at least inspires confidence.

Keep in mind if you go in for a lot of DoF such as in landscapes the whole thing becomes pretty much a non-issue. If you use shallow DoF, getting the AF fine tuned will reduce stress and frustration.

bigjoe

I too have spent hour playing with lenses on my d 500 what software and focusing targets. I come upon several conclusions No Lens is so miss tune as to even bother with trying to Tune it ....the auto focus has been spot on form the very beginning I even went as far to set up cones in a Field and measuring 10 foot increments and put a the target in the middle to focus no abnormalities of focusing was noticed there are some discrepancies but this could be explained by lens displacement or the blades on the diaphragm be misaligned or damaged .... all abnormalities Can be corrected With depth of field

There's nothing wrong with the auto focus on my D 500 not to say that there can't be with others I'm just saying that with all my digital cameras I've had there's been no problems that would even come close to requiring such an endeavor The money I spent on software and a focusing target in my opinion only a waste of time and money

And if there was an issue with either of my cameras with focusing I would take it to Nikon and have them repair it
Like many others I read a lot of information about Tuneing lenses from the talking heads on YouTube to the people who are selling the latest greatest thing to fix this problem that may not exist
It's been my experience [ 35yr ] if the lens is not focusing properly it's been damaged and needs to go in or simply be replaced this is just my opinion isn't worth anything except to me

The only thing I found this feature on either of my cameras to be useful for was hyper focusing