mwsilvers Loc: Central New Jersey

Yes, if I understand you correctly. In my experience, it seems to be more of an issue shooting wide open with fast primes, and less obvious when stopped down. However, if a lens is back or front focusing it will still back or front focus regardless of the DoF

camerapapi Loc: Miami, Fl.

I am entirely on your side.

bpulv Loc: Buena Park, CA

Since you mention manufacturing tolerances and since I was a Quality Assurance Manager for over twenty years, I think there are a few things that everyone should know about that topic. Everything mechanical or electronic has tolerances. Note that I say tolerances, a plural, and tolerances are cumulative.

These tolerances also include the equipment used to measure parameters of a device. Tolerances are expressed with two numbers, usually plus (+) and minus (-), or they could be expressed as a percentage. For example, if I measure the length of something, that measurement will be expressed as for example, 1" +/- 0.005"; or an electrical voltage 1 volt 1V +/- 0.01V". However, you must also add to those measurements the tolerance of the instrument used to make that measurement. So, if the tolerance of the micrometer used to measure the 1" is +/- 0.0001". Note that you ideally want to use an instrument that is ten times more accurate than the measurement you are making. But, that is not always possible because our ability to make super high tolerance measurement tools is limited too. So, algebraically adding the +/- 0.0001" measurement to the +/-0.005", you have now expanded the the tolerance of your measurement to +0.0051" to -0.9949". Now that is not much BUT, as I said, TOLERANCES ARE CUMULATIVE. So, if we connect that part to another part, we must algebraically add the total tolerances of both parts and so on and so on. Taking the tolerances of every measurement used to make any product and algebraically adding them together, the overall tolerance can expand or contract substantially. But in the real world, it usually expands.

What does this mean for the performance of your camera and lens? It means that there is no possible way that any manufacture can make every lens out of the box match every camera body out of the box to the degree that we would like. Therefore, we must live with the fact that lenses must be fine tuned to each body for truly accurate autofocus to perform optimally.

Rab-Eye Loc: Indiana

Watch Steve Perry's video on Nikon AF Fine Tune on YouTube. Because I’m on my iPad which plays through the YouTube app, I can’t post a URL for you.

RRS Loc: Not sure

You are right! The reason so many people think it's not important to "fine tune- Nikon or micro- adjust Canon" could be because they never use their cameras wide open. If your style of photography requires you to shoot wide open then these adjustments can make all the difference between a photo and a sharp photo. With these two procedures by Nikon/Canon you are aligning the camera sensor and not modifying the lens at all. The cameras will remember and store the info so it only affects the lenses that you have aligned. If you only shoot in good light and as you said at f/8 or f/11 you may never see a need to align. It all depend on the degree of miss match, you could use a another lens just like the one you are using and find that it is right on.

TriX Loc: Raleigh, NC

👍👍 Well said.

TriX Loc: Raleigh, NC

I think you’re on to something. After having participated in this discussion numerous times on the forum (I won’t repeat my endorsement of the reasons to fine tune yet again...), my suspicion is that the few really excellent photographers that argue against it and “have never needed to fine tune” typically shoot subjects where the lens is stopped down substantially (and perhaps even manually focused), and the DOF “hides” the AF error. I’m thinking that if they were shooting subjects with an 85mm f1.2 wide open with a DOF of 2”, they might find a reason to have the AF spot on.

dsmeltz Loc: Philadelphia

Yes. In fact when testing the AF you use the lens wide open in order to detect the variance with precision. Before I adjusted my Sigma 18-35 1.8 I tested it at F1.8 not at f11.

mwsilvers Loc: Central New Jersey

I've been saying that, although without the same level of detail, for many years. However, there are still a large number of people who simply are not willing to accept that and expect every lens to be perfect and every camera to be perfect, and don't understand the reason for Micro Focus functionality in camera is because of these tolerance issues. When people say they have owned multiple lenses and multiple cameras over the years and none of them ever needed fine-tuning, I have to laugh. More often than not, they just don't have the appropriate level of attention to detail to notice it.

Some of the arguments against fine-tuning is because the manufacturers don't indicate that it's necessary except under rare circumstances. Of course they don't. Can you imagine the reaction of the public if Nikon or Canon said most of their camera/lens combinations could probably benefit from adjustments as a result of tolerances, especially since they don't include microfocus functionality on their lower level cameras?

dsmeltz Loc: Philadelphia

People who expect that level of manufacturing precision would need to be willing to pay A LOT MORE for the equipment. And I don't me double or triple. It would be an order of magnitude more. I think it is theoretically possible. It just would not be worth the cost.

brucewells Loc: Central Kentucky

Ben, for future reference, there's a 'Share' button below the video frame. If you touch that, options come up and one of them is 'Copy Link'.

mwsilvers Loc: Central New Jersey

Exactly. Frankly, I think that most people who say that it's a waste of time and that it isn't necessary are probably not shooting a lot with fast lenses wide open. To be sure back and front focusing can be identified even at smaller apertures. but it becomes so much more obvious at wider apertures.

Again as I said many people simply have not developed to be attention to detail to notice it. When I started shooting digital back in 2009, I like many newbies purchased a super zoom. And when it came out I purchased a copy of the Tamron 18-270mm PZD which at the time I thought gave me fantastic results. I've looked at that same lens many many times on the same body I used it on back then, a Canon 60D. I'm amazed how tolerant I was of the softness, the distortion, and the fact that it was slightly back focusing on my 60D. It was simply a lack of experience on my part back then. I can no longer tolerate using that lens for even casual shoots.

dsmeltz Loc: Philadelphia

Also images using the newer high MP sensors will show that variance more than the older low MP images.

bpulv Loc: Buena Park, CA

Doubling or tripling the price to get the tolerances required will not solve the problem for the reasons I previously stated. The only way for manufacturers to solve the problem is to either make precision non-interchangeable lens cameras or match each body by serial number to lenses by serial number at the factory. That was actually done in the past by Leica for the condenser lenses in their Pradovit slide projectors. The results were spectacular for more reasons than just the matched condensers. If you ever get a chance, look at slides shot with a fifty year old Leica camera projected with a Pradovit projector. You will never see a crisper image in your life. In fact, if you look at the light on the screen without a slide in the projector, you will observe that the screen is completely white and there is no sign of a rainbow around the edges.

NormanTheGr8 Loc: Racine, Wisconsin

I bought a program from Reikan called FoCal hook my camera up to a laptop and it runs test shots and tells me what to change in the camera settings it also logs the tests for future reference over the last yr I have tested my lenses 3 times 1 changed slightly from the first time . ALL things with moving parts even as precise as our expensive cameras and lenses wear out or at least do not function exactly the way they did out of the box, bumps, bangs, temperature changes can all affect how the lens camera combo sense auto focus. There was a minute difference in each identical part and many moving parts go into one camera thus requiring fine tuning for Optimal image. That's why the manufacturer built the ability to Micro Adjust into our cameras.