After spending a lot of time researching the AF focus adjustment, found on many DSLR camera's, I decided to NOT use the feature. You may come to the same conclusion. I wrote about AF focus adjustment in an article for *LINK REMOVED*
CliffordS
AF Focus Adjustment; the wrong way to go?
(43 posts) (16 voices)-
Posted 1 year ago #
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Go spam somewhere else. Forum doesn't allow advertising
Good little blog though :)
Posted 1 year ago # -
Never intended nor thought of my post as an advertisement. AF Focus adjustment is a topic that has a lot of misinformation on the web. Rather than re-write the info I found it easier to give a link. I was hoping to give info that should be given and discussed.
Sorry if I offended you.
CliffordSPosted 1 year ago # -
TaoTeJared said:
Go spam somewhere else. Forum doesn't allow advertisingGood little blog though :)
TTJ - You are on form with that reply! No mercy! :)
Without reading the blog - @cliffords - are you talking about adjusting for tolerance variations between copies of lenses or just plain old wobbly photography?
If the first, do us all a favor and do a search before you post please? This (backfocus etc) is a horny old subject and is done to death here and elsewhere. If the second, then you'll do yourself a favor if you go make the point on a beginner blog, not here. The regulars all think of ourselves as old pros and know how to brace properly.
Posted 1 year ago # -
cliffords said:
After spending a lot of time researching the AF focus adjustment, found on many DSLR camera's, I decided to NOT use the feature. You may come to the same conclusion. I wrote about AF focus adjustment in an article for *LINK REMOVED*
CliffordSI've read your article, why I wonder?! What is this all about, you have a well behaving lens and you find the focus adjustment useless? You focused on a "cork", whaat?
In my opinion you are greatly underestimating your average photographer. “The company repair shop has many thousands of dollars invested in equipment. What makes you think we can eye-ball an adjustment as accurately?” It's very easy to do, if you do it yourself it takes about 30 minutes to get it spot on.(with a proper test chart/focus target to lock on) In the repair center they can do it in 1 minute. I'm an enthusiast and I don't have this feature on my budget level camera body, but I find it very annoying that my camera lacks this, if I get a lens that's slightly off, wouldn't it be easier for both me and Nikon, if I could do the adjustment at home, instead of sending in both body and lens to their repair center and wait possibly weeks before they take care of it, if they even detect the problem, which is often not the case. I've got 2 prime lenses slightly front focusing, it's very minor in both cases, but noticeable, even annoying at times. Had a 16-85vr which had strong backfocus issues.
Not using AF adjustment is bullshit, I'm sorry. I guess it's useless, when you use a zoom lens that shows a non linear misfocusing nature at different points of it's focal range. I suppose there are other reasons which can make things complicated, like massive focus breathing causing strange focusing characteristics, or focusing shifting.
It's also worth noting that this feature is only a firmware thing, it wouldn't cost Nikon anything to enable it on any of it's bodies.Posted 1 year ago # -
bjrichus, why not read the article and then comment? Instead of starting a discussion, i'm getting attacked on my very first post. It appears I'm not welcomed here.
CliffordSPosted 1 year ago # -
cliffords said:
bjrichus, why not read the article and then comment? Instead of starting a discussion, i'm getting attacked on my very first post. It appears I'm not welcomed here.
CliffordSI have just read the article ... I think I understand where you are coming from now.
Currently I am on site and my cameras/flashes are on charge and waiting for 7pm at the start of an event where I am working tonight, so can post a lengthy comment.
I know most posters here have been involved in photography for many years as either professional or at the very least at informed enthusiast level and many of us are even still at work taking photos (me included), so I suspect this is not a new matter to all.
To be specific in my comments, your blog post does not really raise any NEW questions or bring NEW information to the table, so I am at a bit of a loss to see why you posted it, except for self-promotion.
Maybe you had a bad copy of a lens at some point or a copy of a lens that was at one end of tolerance limits where your camera was at the other and want to blow off steam about how you were treated by the repair shop you used or the amount of frustration you have relating to "My lens is soft" etc. At least that is what I get from your post.
I also don't really see much in the way of a conclusion or asking questions relating to HOW one gets a setup that works well for all focal lengths and all (probably most) apertures. About the only questions I took away from your blog was that you also don't like how to test for backfocus or don't know when to stop testing for it... or at least don't know that most consumers won't even bother... "I can't get it to focus" and again, from reading your post, I'd have thought you might be a camera shop person... But then how could I find out?
Your blog says in the About section that to find out more about you to "See about clifford sarokoff under categories for more information about me." As far as I can recall, using WordPress, you need to include categories to your meta block to have an entry (so you can look at the different categories) actually appear in the sidebar? It isn't. There is no way to view categories.
Oh yes, and what's the the word "Array" on the bottom left of every page that hooks into a JQUERY script? The rest of us who have clients that use Bluehost, generally do a better job of removing left over java script from the many hack attempts on there or is it something deliberate?
And you expect a smooth ride from the ultra critical crew here? Good luck.
Posted 1 year ago # -
I'll soon be flying out to photograph a beach wedding so I'll not be able to reply for about a week.
Nothing new in the article? Show me another post or article that makes a case to return or replace a lens that exhibits focus problem over using the AF Focus adjustment?
Some of the above post indicate that the reader skimmed the article and/or had preconceived ideas.
I wouldn't the use AF Focus adjustment for the reasons stated in the article. While we all have the right to opinions (and Nikon, as stated in my article appears to agree with me)I haven't seen anyone point out mine or Nikon's view. If my point of view has been said before you might be correct in saying it's a tired subject. but since it hasn't.... Just saying.
CliffordSPosted 1 year ago # -
cliffords said:
I'll soon be flying out to photograph a beach wedding so I'll not be able to reply for about a week.
Nothing new in the article? Show me another post or article that makes a case to return or replace a lens that exhibits focus problem over using the AF Focus adjustment?
Some of the above post indicate that the reader skimmed the article and/or had preconceived ideas.
I wouldn't the use AF Focus adjustment for the reasons stated in the article. While we all have the right to opinions (and Nikon, as stated in my article appears to agree with me)I haven't seen anyone point out mine or Nikon's view. If my point of view has been said before you might be correct in saying it's a tired subject. but since it hasn't.... Just saying.
CliffordSOk.
That's fine.
We'll all have forgotten about it and moved on by then.
Enjoy the beach.
Posted 1 year ago # -
I don't agree with the premise of Cliff's article.
The AF Fine Tuning feature isn't there to "fix" a broken lens. If a lens is actually defective, sure you should get it fixed, no one is going to argue with that!
What the article ignores is that you can have a perfectly good lens attached to a perfectly good camera body, and STILL have focusing issues. Why? Because of the dreaded reality of manufacturing tolerances (as bjrichus touched on above).
There are millions of cameras + lenses; it would be impossible for all of them to be manufactured to focus exactly. Instead they are manufactured perform within tolerance ranges.
That's what AF Fine Tuning is for: to adjust for small errors due to tolerances, if required. It's NOT there to fix the lens you've just accidentally dropped, as stated in the article.
Also, it would be pointless to send a good lens that's within spec back to Nikon for repair. They'll probably just send it back. Or, even if they re-tune the lens using their "thousands of dollars" worth of equipment, the lens might still misfocus when used with your specific camera body.
In the "old days", when buying a new lens, one might actually visit the friendly local dealer and "try out" several lenses to see which one fits best (if any). Having AF Fine Tuning means you can make sure the lens + camera combination fits perfectly.
Today, a professional photographer should definitely test any new lens to check for small focusing errors and make any adjustments as required. Yes, that includes testing with all the backup cameras as well. Your clients are paying you for that.
Posted 1 year ago # -
If you send the lens to Nikon for focus adjustment, they'll ask you to send the camera too. Just sending in the lens is pointless, since there are two points that need adjustment, the lens and the camera.
Posted 1 year ago # -
PB PM said:
If you send the lens to Nikon for focus adjustment, they'll ask you to send the camera too. Just sending in the lens is pointless, since there are two points that need adjustment, the lens and the camera.And what about the collection of other lenses you may have? Send them all in too? That is clearly not the way to go... so what is the solution? complain and demand refunds? Only buy one lens or keep a small collection of lenses? Or as you suggest, buy local and try before you buy?
Posted 1 year ago # -
Personally, if I was having problems I would send in the lot and get the set adjusted. Whats the point of having one lens adjusted if the others are off (even if just a little)? It might be a pain, but it is easier long term. I'd rather be out of action for a week or two than constantly having to check to make sure my lenses are fine tuned enough. AF fine tune is a great idea, but you have to keep in mind that AF fine tune is effected by the distance to the subject that you fine tune at. I found that if you shoot close to infinity often, adjust for that, if you shoot close adjust for that. A happy medium can be hard to find IMO.
Posted 1 year ago # -
To me the AF fine tune is really on good on primes and if you are doing macro work. Focus always shifts with zooms - it is just usually shifts ever so slightly within the DOF of 2.8 (or whatever beginning F range). The thing is, if you lens is really out of wack, you are talking about inches, not he MM the AF fine tune works at.
Posted 1 year ago # -
Wow, I love this forum, lots of bickering.... I have several of Nikons best lenses on old DX bodies... D90, D200. Some of the difficulties I have with autofocus is in forgetting the darn settings for all the strange behaviors, closest focus, left, right, etc. however, one area of interest I have discovered in my new world of "autofocus" is the need to allow the lens to fix on a moving object rather than point and shoot. An example, a bicycle peleton, moving past at 20 mph, going up hill, attempting to snatch single riders from nearly a head on position.... as the group moves by and the lens is going from one rider to another there are times when the autofocus simply cannot catch up with my rapid change of subject. And this is simply my learning curve with a fantastic lens... 400mm f/2.8. As I often am shooting very quickly moving scenes, dynamic activities, I have found the autofocus simply has limits. On occasion the camera will fire with the focus slightly out. Rechecking suggests to me an operator error vs. camera malfunction. In still life/ macro, etc., I will almost always be checking every exposure by magnifying about 20X or what ever the max is on the viewer on the camera back, and if I do not like the focus, I change it.
So far, I will try not to send anything back to Nikon, unless it is grossly out of whack. When we shot film and manually focused, bracketed exposures in color, and had some concern regarding number of exposures, I do not remember this problem. But maybe my impatience now is a contributor to the "out of focus problem."
Posted 1 year ago # -
msmoto: Newer Nikons have a custom menu setting for AF-S or AF-C priority selection. (Your D90 doesn't but I expect your D4 will although it may be labeled differently in the menu structure, since the D4 is a new generation it may also start using a new menu structure.) You might try experimenting with them when you get your D4. If I set my D7000 to focus priority the shutter will not fire until the lens reports it is in focus. If I set it to release priority the shutter will fire whenever I press the shutter release whether or not the lens is in focus. I have my D7000 set to focus priority but I find in some very fast moving action I miss shots (I press shutter button and nothing happens). If I had it set to release priority the shutter would fire but what use would it be to have out of focus shots?
Posted 1 year ago # -
donaldejose said:
msmoto: Newer Nikons have a custom menu setting for AF-S or AF-C priority selection. (Your D90 doesn't but I expect your D4 willThank you donaldejose...
This is my understanding of what the D90 does:
Autofocus mode
Auto select AF-A (default setting) Camera automatically selects single-servo autofocus when subject is stationary, continuous-servo autofocus when subject is moving. Shutter can only be released if camera is able to focus.AF-S Single-servo AF For stationary subjects. Focus locks when shutter-release button is pressed halfway. Shutter can only be released when in-focus indicator is displayed.
AF-C Continuous-servo AF For moving subjects. Camera focuses continuously while shutter-release button is pressed halfway. Photographs can be taken even when in-focus indicator is not displayed.
Thus in single and auto, the shutter is locked unless the subject is in focus. In continuos, which is what I use mostly for a variety of reasons, it does allow the taking of out of focus shots, but also is sometimes quicker to follow and focus than the other modes... or so it seems. "C" allows more "operator errors" but maybe more control?
Anyway, I think most of my problems come from me and not from any camera error. The D4 will be interesting. I am studying the D3s manual, looking at all the various things, then I will find I like to have the camera set for only a limited number of adjustments, so I can not get too confused.... old folks do this, you know, ha, ha, ha.

Posted 1 year ago # -
Much of this is copied over from a different thread. Hopefully it will help clear up some misconceptions about AF, Liveview and AF fine tuning. If the misconceptions are mine, then all the better....
Liveview and its' associated AF system uses the data at the image sensor, so Liveview focusing (contrast detect) is very accurate, (but slow) since the liveview image is the actual image that will be recorded. The normal AF system uses an AF module (Phase Detect) that is separate from the image sensor (and fast). Manufacturing variability can result in a slight difference between the focus that Phase Detect AF system "sees" and what occurs at the image sensor. This difference between the Phase Detect AF system and the image sensor can result in a focus shift in the image that can occur when using the AF phase detect system. AF fine tuning seeks to determine the difference between what the image sensor sees and what the AF system sees (when using AF through the viewfinder) and compensate. This compensation varies from lens to lens due to the manner in which manufacturing tolerances stack.
Nikon calibrates all of its AF systems at the factory and adjusts the path lengths so that there shouldn't be problem. AF fine tuning is subtle and the capability only shows up on Nikon's top level cameras: D7000, D300 series, D700, D800, D3 series, D4.
Unless you have a good test strip and target, and a solid tripod, AF fine tuning can be frustrating. Basically, in order to be successful at AF fine tuning you need to eliminate all other possible sources of blur in the image. This includes wind, mirror slap, tripod shake, shutter press induced vibration etc. A tripod is NOT optional.
Your focus target should be vertical and next to the middle of your inclined test gauge. Set the aperture wide open for minimum DoF. Focus on the target in liveview, snap a few photos (to make sure they are all the same), and then do the same with standard AF. If the in-focus portion of the inclined test strip is not the same as the liveview sample, you may benefit from AF fine tuning. (+) numbers move the focus point away from the camera whereas (-) numbers move the focus towards the camera. Once you know which way you are out, you can add in adjustment until the two match. ... Sometimes I just take a bunch of pictures at different fine tuning settings and pick the best at the computer. Note: Be sure to defocus the lens between test images so that the AF system has to bring the lens back into focus.
If you search "LensAlign", you will see one of the tools available. You can do the same thing with a yardstick or ruler. Youtube has several tutorials as well. However ... If you are happy with your lens and the pictures you are taking, don't worry about it and have fun. If you find that for the way you are using your photos the focus seems to be off in a consistent fashion, AF fine tuning may be the key.
If you want the piece of mind, build a test rig (or buy one) and get the two AF systems to match, or get the viewfinder AF system (Phase Detect) to match your best manual focus obtained while zoomed in using liveview.
I am probably way too anal about this stuff, but I get some satisfaction out of knowing that my lenses are properly setup. Remember that AF fine tuning is not even available on many Nikon bodies; the reason for this is that the issue is subtle and many folks will never notice. However, with the D800 / 70-200 f/2.8 combo, AF fine tuning (or the lack thereof) may rear its head.
As an additional note on zooms: Many Nikon zoom lenses are effectively parfocal, or close to it. This means that the lens will stay in focus as it is zoomed in and out. (the 70-200 f/2.8 is a good example) For these lenses a single AF adjustment works throughout the zoom range. For all lenses, fine tune the AF at the long end where the DoF is minimized and set the camera to target distance so that the target always fills up about the same amount of the frame for each lens being tuned. (this just makes it easier to judge) A good distance between the camera and target is about 30X the focal length. If the lens being tuned has a large amount of focus shift, the AF fine tuning may not be correct at all focal lengths...in this case if the lens is most often used at a given focal length it may make sense to re-tune at that setting.
Hopefully this all helps clear up confusion and doesn't add to it....
Posted 9 months ago # -
@Eric
Thanks
Posted 9 months ago # -
@Eric: Thanks for that. One question: did you get the "30x focal length" from somewhere or is this your personal experience?
Posted 9 months ago # -
@Correlli - I have seen recommendations from 25x to 50x. It is not too critical. For my target, around 30 is a good number to give me a reasonably sized image. I also like the closer targets because the DoF is shallower thus making it easier to judge what is happening on the inclined ruler.
Posted 9 months ago # -
Hi Eric, thanks again for the info. Two last questions:
- is there any specific target that you can recommend?
- how did you make sure that the target was perpendicular to your optical axis?Edit: never mind, I just saw that recommendation and that the recommended tool has got a build in mechanism for alignment.
Posted 9 months ago # -
@Correlli - It sounds like you are going to buy the commercial product. Here's a hint. When trying to align the vertical target with your lens, leave the lens cap on when aligning from the back of the target. That nice white Nikon on a black background is lots easier to work with than the open end of the lens.
Posted 9 months ago # -
Hi all. Quick question, do you routinely run the focus calibration on your camera/lens combinations? I've never done it, and always been a bit scared to try, but do you all calibrate regularly? I presume the first thing I need is a way of checking wether I have any focusing issues, has anyone tried using a "Focus Pyramid"? Seem like a reasonably inexpensive way of highlighting any problems? Any thoughts?
P.S. Thanks Eric for your tutorial on how to actually go about checking and adjusting if necessary. I'm sure the info will come in very handy.
Posted 9 months ago # -
@ SkintBrit
I have not done the procedure yet, but definitely recognize the need. And, I made my own target. Fortunately I have a 60 foot long garage and will do this inside with no wind, on a tripod. The problem comes in several areas as I see it. Macro... clearly the small DOF will make sharp focus critical...portraits...getting the exact focus on the eyelashes, again at large apertures and small DOF, and with the long lenses, trying to focus on a helmut of a driver the small DOF agains requires precise focus. And, if done manually, no problem, but if the autofocus is used and running the focus to the incorrect point, yikes, no keepers...
So, I will get to this fairly soon as the checking and compensation of the errors drives me more nuts than I already am!
Posted 9 months ago #
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