topic Re: Sudden fuzzy photos - EOS80D in EOS DSLR & Mirrorless Cameras

Sudden fuzzy photos - EOS80D

aubreys — Sun, 31 Mar 2019 17:24:18 GMT

I have an odd problem with my camera. I have been using my camera a lot this week due to graduation photos, so I know this issue is brand new and that the camera was working perfectly fine very, very recently.

In short, my camera's photos are coming out extremely fuzzy. Auto mode seems to help, but not entirely, and I do not know how to fix the issue. Here are examples of photos I took recently, and photos I tried to take yesterday. I'll also show the comparison between manual and auto mode from yesterday.

This photo was taken before the camera experience these problems:

Here's what my photos looked like yesterday, same lens, extremely similar manual settings:

Nothing in this picture is in focus.

Auto-mode was slightly better, but I still notice some fuzziness...

Any ideas? Has this happened to anyone before?

Re: Sudden fuzzy photos - EOS80D

TCampbell — Sun, 31 Mar 2019 17:58:47 GMT

I noticed the out-of-focus shot is taken at f/1.8 (shallow depth of field).

I also noticed you set the focus mode to AI-Servo (continuous). For non-moving subjects, use 'One Shot' mode.

Two bad things happen when you use AI-Servo (which is really only meant for action photography such as sports).

AI-Servo uses a behavior called "release priority". When you press the shutter button, it WILL take a photo whether the camera has had time to accurately focus or not.
AI-Servo expects a moving subject and may try to react to any perceived motion (the slight motion of your body) and shift focus.
Since you used f/1.8, the depth of field is thin ... so it's easy to miss focus. (is there a reason you wanted to use f/1.8?)

Use "One Shot" mode. One shot uses "focus priority" and will not take a shot until at least one AF point has locked accurate focus. It does not expect a moving subject (once focus is completed, it stops attempting to re-focus ... which also means that camera to subject distance should not be changing.)

The backgrounds are a bit blown out in these images. Use of fill-flash will help here by filling in the shadow so the camera can reduce the overall exposure and that will bring down the over-exposure in the background.

Your third image is much sharper than your first image (compare the definition in the subject's eyebrows). But this is the result of the low (f/1.4) aperture used in the first image which created a very shallow depth of field. In the first photo, though I can see some backlit hair on the subject's arms and the focus looks good on her dress, her face is slightly forward of the focus distance and is falling out of focus due to the shallow depth of field (low focal ratio).

In the third photo you used f/5.6 -- considerably broader depth-of-field ... so your subject's face and your subject's shoulders are within the depth-of-field.

Re: Sudden fuzzy photos - EOS80D

aubreys — Mon, 01 Apr 2019 15:24:29 GMT

I appreciate your feedback.

I noticed the AI-Servo, and I am still getting similar resutls in One-Shot mode. I was hoping that was it.

I understand what you're saying about f/1.8, and I am not looking for advice for my photography, although I appreciate it, it is simply not what asked.

Compare the two first images. Similar settings. But the second image has some sort of distortion. And, the same results are coming up even in One-shot mode. Both of the first two images have a "wide open" aperture, but they are extremely different in quality. I'm not claiming one is perfect. There is just a distinct difference that is causing me concern and wondering about potential damage...

So to clarify: I am not ask for shooting advice. I am asking about potential damage to my camera and possible solutions, things to check/test, etc.

The problem does worsen when the aperture increases, but comparing before-and-after of the issue arising with two large aperture settings shows that something is wrong outside of my ability, and it is not user error.

Thanks for you opinions, though.

Best,

Aubrey

Re: Sudden fuzzy photos - EOS80D

TCampbell — Mon, 01 Apr 2019 18:24:16 GMT

The 2nd image is simply missed focus ... plain and simple. But that's easy to do in AI-Servo mode (press the shutter button too quickly and you'll get that result). There is no unusual distortion (other than missed focus). Everything I see in the photo is something I would expect to see in a de-focused image at large aperture.

I'm looking closely at your 3rd image and I don't see any issues that make me worry about a camera (I see over-exposure, but nothing that indicates the camera or lens isn't performing correctly).

The first image also has missed focus (focus is at shoulders instead of face).

@aubreys wrote:

So to clarify: I am not ask for shooting advice. I am asking about potential damage to my camera and possible solutions, things to check/test, etc.

I don't see anything in these photos that suggests that your camera or lens is damaged. I'm in specing the out-of-focus blur to see if I can detect any patterns that might indicate de-centered optics (e.g. if the lens took a hard hit and was internally damaged such as optical components were askew) - but I'm really not noticeing evidence of that. Out of focus blur appears to be more-or-less symmetric. Sagital vs. Meridonal blur seems to remain consistant around the corners.

If you are referring to the "bokeh balls" -- that's normal for out-of-focus blur when points of light are peaking through the gaps between tree leaves. It's nothing to worry about (and a lot of photographers use it as an artisitic effect. You can even create "designer bokeh" by using custom-cut large aperture masks that resemble things like stars or moons or other shapes.)

Also, the 3rd photo (I'm not sure what you're seeing here) looks fine to me -- and is sharper than your first photo. I think you mentioned this is an example of photo that makes you suspect a problem and you posted the first image of an example of the lens & camera not having a problem. I think the first photo is a bit soft in the face ... and the third photo is better. I'm checking the out-of-focus background (in both) and everything appears to be symmetric (no side of the frame is noticeable more or less sharp than the other side.)

These are small JPEG images so I'm not looking at big RAW source files, but I'm not noticing problems that would indicate camera or lens damage.

And while you say you were not asking for shooting advice ... I'm still giving shooting advice. This is because the "things to try" are changing the camera to a mode where you're likely to get better results.

Use of AI-Servo is not meant for non-moving subjects. Certainly it is your camera so you can do as you want. I'm just pointing it out because often a photographer doesn't realize they switched a mode and never switched it back (e.g. they forgot it and didn't realize the camera was still in a wrong mode.) It's very easy to imagine missing focus in that mode because it requires a slightly different shooting style. (it's not a camera defect)

Do not be too quick to blame the equipment.

Re: Sudden fuzzy photos - EOS80D

aubreys — Mon, 01 Apr 2019 20:13:47 GMT

It is not plain and simple. I use this camera a ton. And, I have noticed something different than usual. You can choose to not trust my opinion that it is not simply misfocused, or you can move on. I am confident in my assessment, and have had other professional photographers look too. After using the camera and giving me their (multiple, separate, unbiased) opinions, they are also saying it is NOT user error and that something is strange about the camera when the aperture is higher than 5. This has not happened before. It is a new issue that I wanted some advice about. If it were user error this would have been happening for the last two and a half years 🙂

Thanks again for your time towards the manner, but I am going to ask you to please refrain from commenting again.

Re: Sudden fuzzy photos - EOS80D

TCampbell — Mon, 01 Apr 2019 23:02:24 GMT

I am trying to be gentle. You are resisting the notion that the issues may possibly be operator-error. I will need to be a bit more direct.

Is it *possible* that your camera has an issue? Sure. It's possible. It's just not likely based on the sample images that you posted and the settings that you chose (based on viewing the image EXIF data).

The likely issue is that your choice of settings ... AI-Servo and wide aperture ... resulted in missed focus. This isn't a camera issue -- it's a photographer issue. (Those other photographers are wrong). When you use AI-Servo, the camera doesn't wait for focus confirmation before it takes the shot ... it's on you to half-press the shutter, wait until you believe it has locked focus, then full-press the shutter to take the shot. If you focus & recompose, this will fool the camera into believing the subject moved and require a re-focus (which wouldn't happen in One-Shot AF mode). Canon documents this. There are videos and books that explain the focus systems and the nuances of how each mode behaves.

To isolate the issue to the camera, you'd need to perform some careful testing. You would need a proper focus calibration target (not just any subject) which provides a flat, high-contrast surface as well as an adjacent scale laid at an angle which makes it possible to detect if a camera & lens has a front-focus or back-focus issue. The camera must be on a tripod (hand-holding is forbidden as this completely invalidates the test and puts the blame back on the photographer). Camera must be in "One Shot" AF mode. A specific AF point must be selected (rather than automatic point selection) and typically it's the center point. The shot should be triggered either via the self-timer or via a remote shutter release (such as the phone app, or a wired or wireless release) but not via physically pushing the shutter button (which would create vibration).

You can also test the camera by using "live view" mode which uses a completely different focus system vs. the one the camera uses in viewfinder (normal shooting) mode.

Your third photo (I'm not looking at the EXIF right now but I thought I recall that it was f/5.6) came out with the most accurate focus of any photo you posted (and if I understood your explanation of the three photos ... this was one that you considered a photo that showed the camera having focus problems). This adds more weight to the idea that the issue with photos #1 and #2 are photographer issues and not camera issues (otherwise you'd need to explain why a camera & lens with a focus problem just took an accurately focused photo). Unless you were trying to focus on the building or the tree ... that camera is working correctly.

I can sense you really want to blame the camera -- that's premature. There are a few photographer issues that need to be isolated before we blame the camera.

If you'd like, you can contact Canon support and have it sent in for evaluation. I suspect you'll get the camera back with a report that the camera is functioning properly and no issues were detected. Which means you might waste a bit of money and be without a camera for a few weeks. But if it would put your mind at ease ... maybe the investment is worth it.

Re: Sudden fuzzy photos - EOS80D

Anonymous — Tue, 02 Apr 2019 01:01:39 GMT

I think photo 3 is sharper than the first photo, but the first photo has a lot more contrast. The second photo is not focused well, anywhere in the photo. The third photo is focused well.

I believe you might be seeing a lack of contrast in the photos 2 and 3. Perhaps your picture style in the camera was changed (less contrast) from your first photo, or a lens hood is needed to block light coming at an extreme angle into the lens, causing a washed out look. I edited the photo in photoshop and increased contrast and added some sharpening, and it looks ok after adding contrast.

Re: Sudden fuzzy photos - EOS80D

Waddizzle — Tue, 02 Apr 2019 09:14:24 GMT

@aubreys wrote:
I have an odd problem with my camera. I have been using my camera a lot this week due to graduation photos, so I know this issue is brand new and that the camera was working perfectly fine very, very recently.

In short, my camera's photos are coming out extremely fuzzy. Auto mode seems to help, but not entirely, and I do not know how to fix the issue. Here are examples of photos I took recently, and photos I tried to take yesterday. I'll also show the comparison between manual and auto mode from yesterday.

This photo was taken before the camera experience these problems:

Here's what my photos looked like yesterday, same lens, extremely similar manual settings:

Nothing in this picture is in focus.

Auto-mode was slightly better, but I still notice some fuzziness...

Any ideas? Has this happened to anyone before?

I do not see any EXIF data. What lens are you using? Many consumer lenses are considered to be soft when shot wide open. I do not think the problem is soft optics as much as it is inconsistent focusing. The AF motors do not perform well enough to produce consistent results with narrow DOF.

Which part of the photos are you describing as extremely fuzzy? I do no see anything extreme, but maybe focus is a little soft. But, soft focus is to be expected on images posted in the forum, due to the file size limitations.

You asked for ideas. Do not forget that. You cannot determine the problems because you are operating from a baseline set of false assumptions, first and foremost being that there is something that must be wrong with the camera. I suspect cheap lenses.

Re: Sudden fuzzy photos - EOS80D

kvbarkley — Tue, 02 Apr 2019 12:40:50 GMT

If you think something is wrong with the camera send it and the lens to Canon for them to check it out.

Re: Sudden fuzzy photos - EOS80D

PaulSoebekti — Tue, 02 Apr 2019 16:51:52 GMT

Hi Aubreys.

I own this lens as well as the mark 2. It's a lens with a steep learning curve ...

The way you hold the camera at the time of capture is critical because of its weight.

Assuming that you support the camera & lens with your palm under the lens - sharp pictures can be had..

I don't see the in-focus point(s) on DPP (Canon's software).

img_1402: EF35 f1.4L; Spot metering; AV 1.4; TV 1/250; One-shot; Manual; Sharpness ?;

img_5237: EF35 f1.4L; Evaluative metering; AV 5.6; TV 1/160; One-shot; Night Scene; Sharpness 3;

img_5244: EF35 f1.4L; Spot metering; AV 1.8; TV 1/1000; Servo AF; Live View; Shapness 2;

As you can see the three pictures were taken with different setting(s) that result in different outcomes.

Spot metering is dependent on where the main focus point falls (i.e. on a dark pixel or a light coloured one, affecting contrast, and perceived sharpness) and is most effective when the subject fills all or most of the viewfinder.

Take some test shots with the camera mounted on a tripod with the same settings (i.e. evaluative metering, one-shot, same Av, say, 2.5, same sharpness, etc) - to know how the lens behaves under different subject and light conditions.

I don't think there is anything wrong with your lens and/or camera.

Regards,

Paul

Re: Sudden fuzzy photos - EOS80D

kvbarkley — Tue, 02 Apr 2019 17:15:45 GMT

"Spot metering is dependent on where the main focus point falls (i.e. on a dark pixel or a light coloured one, affecting contrast, and perceived sharpness) and is most effective when the subject fills all or most of the viewfinder."

I am not sure what you mean by this, but spot focus is always at the center of the viewfinder:

Somehow, in a way I have never understood, evaluative metering is linked somehow to the focus point, but not spot metering.

Re: Sudden fuzzy photos - EOS80D

PaulSoebekti — Tue, 02 Apr 2019 19:25:10 GMT

Hi Kevin.

Evaluative metering takes the whole viewfinder's scene in account to determine shutter speed, aperture, and iso settings, while spot metering concentrates primarily on the 3.8% area around the focus point - then 'looks' at the whole scene, secondarily.

Spot is effecitive when photographing small objects/areas as it 'samples' a relatively small area (i.e. 3.8% vs 100%) - to get the 'most pleasing' exposure.

Regards,

Paul

Re: Sudden fuzzy photos - EOS80D

kvbarkley — Tue, 02 Apr 2019 19:31:25 GMT

Right, which is not what you said above. And I don't think that spot metering "looks at the whole scene secondarily", that is center weighted average, which I did not show in my screenshot above.

Re: Sudden fuzzy photos - EOS80D

Waddizzle — Tue, 02 Apr 2019 19:49:41 GMT

Spot metering in the 80D is only measured at the center AF point. Always. You can select any AF point you wish for focusing. Spot metering is always at the center.

Re: Sudden fuzzy photos - EOS80D

ebiggs1 — Thu, 04 Apr 2019 14:58:22 GMT

I do not want to beat this to death but you really need to re-read Tim Campbell's suggestion and advice.

First, a camera is not a likely source for blurry pictures. It can be, but not the first place to look. The lens would be the first place. But that too is behind user mistakes or error. Knowing you are probably not going to heed this advice, your only next solution is to send the camera and lens to Canon for a C&C. You will never otherwise be satisfied it is not the camera/lens and quite possibly you.

Re: Sudden fuzzy photos - EOS80D

aubreys — Fri, 05 Apr 2019 22:14:34 GMT

Oops I meant to update this - it's been solved!
It turns out the lens had damage. Thankfully my camera is fine. When I tested out other lenses the issue was no longer there, and when I let my professional photographer friend use the lens in question she also was not able to produce photos.

Thanks anyways! 🙂

Re: Sudden fuzzy photos - EOS80D

amfoto1 — Sat, 06 Apr 2019 19:42:49 GMT

@aubreys wrote:
Oops I meant to update this - it's been solved!
It turns out the lens had damage. Thankfully my camera is fine. When I tested out other lenses the issue was no longer there, and when I let my professional photographer friend use the lens in question she also was not able to produce photos.

Thanks anyways! 🙂

From your images, I doubt there is anything wrong with the lens.

It is most likely the problem is how you are using it. You appear to be using too large an aperture too close to your subject, simple as that.

You have been given a lot of misinformation in some previous responses....

1. Spot FOCUS and Spot METERING are two entirely different things and have relatively little to do with each other, aside from the similarity of the names of the two features. 80D has spot metering but 80D does NOT have spot focus. So it's really a moot point in this case. But... just to clarify.... Spot focus is a high precision focus mode that uses a single AF point that's smaller than usual. It's ONLY found on the cameras with 61--point and 65-point AF systems (1DXII, 5DIV, 7DII). Spot focus IS NOT restricted to the center of the image area. It can be done with any ONE of the AF points in the array. Spot focus works well when trying to photograph a subject that's behind a tangle of branches, for example. It does make AF slightly slower, so may not be ideal for faster moving subjects.

An earlier response shows how spot metering compares to other metering patterns. When using spot metering, in most Canon models the metered area is fixed. Only the spot delineated by the circle at the center of the image area is being measured. A few of the very high-end pro camera models have "AF linked spot metering", where the spot being metered can be located elsewhere in the image area... This was first introduced on the EOS-3 film cameras I used years ago and essentially spot metering is tied to and "follows" the active AF point. On various models I've used with this feature, the camera needs to be restricted to using a limited number of AF points (EOS-3 only use 11 AF points with it, if I recall correctly).

Although it's not the same as AF-linked spot metering, Evaluative Metering pattern acts somewhat similarly. It measures the overall image area, but it puts extra emphasis on the area right around active AF point(s). In other words, it gives priority to whatever you are focusing upon.

2. There is also misinformation about how AI Servo works and using it with stationary subjects (which is something I do 95% of the time). IN FACT, AI Servo is a good, all-around focusing mode... But first you need to understand the workings all three of the focusing modes the camera offers:

One Shot focus mode is designed for stationary subjects ONLY. AF starts when you half press the shutter release or press the AF On button on the rear of the camera, AF achieves focus... then it stops, "locks", and gives you Focus Confirmation (green LED in the viewfinder, red flash in some camera, audible "beep" if you have it enabled). That's fine so long as both you and the subject remain stationary. IF THE SUBJECT MOVES and/or you move and the distance between you changes, focus will be incorrect unless you consciously re-do it.

Another possible problem with One Shot is that some modern zoom lenses are "varifocal" designs... which means they do NOT maintain focus when zoomed. If you are using this type of lens, perform auto focus, then change the focal length of the lens, you MUST re-do focus or it will be inaccurate. "Parfocal" zooms that maintain focus precisely when zoomed are more complex and difficult to build, so tend to be more expensive. Since auto focus has become almost universal and can compensate for it (when used correctly), many manufacturers have resorted to varifocal zoom designs to help keep the cost of manufacture down and be able to offer competitive pricing.

AI Servo focus mode is designed for moving subjects, but is also can be used with stationary with some minor limitations, unless other techniques are used in combination with it. Once you start AI Servo focus running, it does so continuously until you stop it by lifting off the button or finish taking the shot. While it's running AI Servo constantly updates to maintain focus on the subject (so long as you keep the active AF point on the subject). There is no Focus Confirmation in AI Servo.

It is NOT correct that AI Servo always causes the shutter to release whether or not focus has been achieved, reducing focus accuracy. IN FACT, there is a setting on 80D and many other models that lets you prioritize how the camera handles the situation. Page 418 of the 80D user manual discusses how to set Custom Functions II-4 and II-5. These only apply to AI Servo and let you select whether you prefer the camera go ahead and releast the shutter even if focus hasn't been fully achieved, or if you are willing to accept a possible slight delay of the shutter release while waiting for the camera to achieve focus. Setting the priority all the way to the "focus" side of the scale assures the latter (and is what I use, personally).

There are two different Custom Functions for this purpose. CFn II-4 effects only the first image in a consecutive burst of images, if you have the camera set to a high frame rate. It will also effect a single image when drive is set to that and AF is in AI Servo mode. CFn II-5 determines how the camera treats the second and all subsequent images in a consecutive burst. It will not have any effect if you are using the camera in single shot drive mode with AI Servo focus mode.

The reason for these options is that in some action shooting situations it may be more important to "get the shot" than for focus to be perfect. Maybe you're using a smaller aperture anyway, that would cover any minor focus error and so might opt for the shutter release to be as fast as possible. But, again, neither of these Custom Functions have effect in One Shot focus mode.

AI Focus is the third focus mode. But it actually isn't a focus mode at all. It's automation where the camera is supposed to decide for you whether or not the subject is moving, then switch to use the correct focus mode: Either One Shot (stationary subject) or AI Servo (moving subject). Personally I haven't used this focus mode in many years. I avoid it. When I experimented with it on older cameras I found it seemed to slow AF, sometimes didn't choose correctly or sometimes wouldn't switch modes if a stationary subject started moving or vice versa. It might be a hint that the most pro-oriented Canon models - the 1D-series cameras - don't even have AI Focus mode. They only have One Shot and AI Servo.

Now that you know how the focus modes work, when to use them is the next question. Personally I use AI Servo almost all the time with both moving and stationary subjects. Partially this is because I shoot a lot of action and sports.

Something important - I always use Back Button Focusing (BBF). This is necessary in order to use AI Servo in some situations, such as when using a focus and recompose technique. In combination with AI Servo, BBF it puts me in more full control of exactly when and how the AF functions.I can turn it on and off with the simple press of the AF On button.

Setting up BBF on more recent camera models is no big deal. In most cases, it's just a matter of modifying how the shutter button works, setting it so that a half press of it doesn't start AF. The AF On button is already set up to control AF, so all that's being done is removing that function from the shutter release button (Custom Function for button assignments, navigate to the shutter release button and set it to "meter" instead of "AF". Note: Some Canon don't have an AF On button, but can still be set up to do BBF using the * button, which normally provides AE Lock (I recommend to set the CFn so that there is not AE Lock... If needed you can always set the camera to M and get the same effect as AE Lock).

An advantage of always using AI Servo is that its continuous focus will automatically correct any loss of focus if using a varifocal zoom. The AF system will instantly correct focus. One Shot can't do that.

It's also important what "focus pattern" you choose to use. The 80D has four "AF Area Selection Modes", as Canon calls them. They are: Single Point/Manual, Zone (9-point), Large Zone (15-point) and All Points/Auto. (Note: Some other models incl. the 7D Mark II that I use have those plus three more: Spot Focus, 4-point Expansion and 8-point Expansion.)

The most accurate way to focus is Single Point where you manually choose the AF point you want the camera to use and place it right where you want the camera and lens to focus. This is what I use most of the time (with AI Servo and BBF) and I get upwards of 95% of my shots acceptably focused. It's more work for me to use the camera this way, but it insures the most accurate focus.

Any of the multi-point patterns leave it up to the camera to decide where it will focus. Usually it will focus upon the closest object covered by an active AF point. This may or may not be where you want it to focus. You are leaving it more to chance, when you don't select the AF point yourself and keep it right where you want the camera and lens to focus. Of course, it's more work to do this (as is using BBF, described above).

The multi-point patterns are useful in certain situations. For example, a rapidly moving bird in flight can be difficult to focus upon and one of the zone patterns can be useful. This will work best if the bird is against a plain sky or a very distant background with little detail that might "distract" the AF and cause it to miss focus. I suppose the same could be true of All Points/Auto, though to be honest I never use that. It's more a "point n shoot/camera phone" focus method, as far as I'm concerned. The two Zone patterns are also "auto", but more limited in what the camera can opt to use.

Finally, the reason your images are "fuzzy" is because you are using such a large aperture and are fairly close to your subject, which results in relatively shallow depth of field (DoF). Assuming none of the images are cropped... Your first image is "sharp" because you are at a greater distance from your subject ... and you got lucky using f/1.4 aperture. The second and fuzziest image is both closer and shot at f/1.8, making for less DoF. The third image is shot at the same distance, but when you switched to an "auto" mode the camera selected f/5.6, which greatly increases DoF. Their abiliyt of render shallow DoF is one of the reasons large aperture lenses are "challenging" to use. It makes that type of lens more unforgiving of any minor focus error.

A 35mm lens at 5 feet with f/1.8 aperture renders DoF of f inches. That's the plane that will be in acceptably sharp focus. It doesn't take much focus error at all for that to cause problems in images. The "error" might be as simple as the camera focusing on the tip of the person's nose in a portrait or the closest wingtip of a bird flying past. (Longer focal lengths will render even shallower DoF, but you will be standing farther from your subject in order to frame the subject the same way, which increases DoF.) For comparison, the same lens and distance using an f/5.6 aperture renders DoF of 18 inches... much more forgiving. Many lenses also aren't at their sharpest wide open... are sharper stopped down to a middle aperture.

EDIT: You mention using "Auto". If by that you mean the "AUTO +" on your camera's mode dial, then you are using All Points/Auto and AI Focus modes. The camera forces you to use those, in that mode. It also prevents you from savign RAW files, only allows JPEGs, makes the camera use Program exposure mode with Program Shift, won't let you use Exposure Compensation and other highly automated modes. It's essentially a "point n shoot/camera phone" mode that takes away all of your control of the camera..

If you mean that you set the AF point selection to All Points/Auto, that's different... You can still choose your own exposure mode, use Exposure Compensation, etc., etc.. But to some extend it's still allowing the camera to decide where it's going to focus... rather than you making that decision.

Also, your camera has a Micro Focus Adjustment feature, which might be needed with that particular lens. Every lens and camera combo is different, so this is provided on the 80D and higher models to allow you to fine tune autofocus to be as precise as possible. There are instructions in the user manual how to use it.

Hope this helps!

***********

Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2), other cameras, various lenses & accessories
FLICKR & ZENFOLIO