AF misses. Canon

Thanks for the answers! I will take all the opinions into consideration and explore this problem more precisely the next time outdoors. I notice this problem only when upload photos to computer, never have time while shooting. But now I will explore it right away. I will let you know for sure! Thanks everyone!

ThrillaMozilla wrote:

brightcolours wrote:

The f-value is not important, and it and the exposure time are in the EXIF.

The EXIF data are not available to me. Do you have them?

Download the images, they have the EXIF.

And the F stop is relevant if it is very small, or if it is so small that the shutter speed is too low. Anyway, I have no idea how the pictures were taken, except that it was broad daylight.

ThrillaMozilla wrote:

You can get that blink even if auto focus is off, and even if it's not focused at all.

When an AF point blinks red, it means that AF point has acquired focus! The green focus confirmation light just reflects the fact that one or more AF points have blinked, nothing more. If the photo shows out of focus at the blinked AF point, something is wrong. Lens? AF sensor and image sensor chip not on the same plane? Or shooting technique? Put the camera on a steady tripod and figure it out.

ThrillaMozilla wrote:

rwl408 wrote:

ThrillaMozilla wrote:

You can get that blink even if auto focus is off, and even if it's not focused at all.

When an AF point blinks red, it means that AF point has acquired focus! The green focus confirmation light just reflects the fact that one or more AF points have blinked, nothing more.

No, that's the way it seems to work under most conditions, but it's not how these cameras actually work. I'm sitting here with my SL1 (which is working perfectly, in case you're wondering), and I can confirm that these cameras don't work that way.

With OneShot focus it's easy to get the center point to blink without a focus lock. I just focused on a nearby flat surface with no contrast, and held the shutter release half depressed. The center point blinked, and the green focus light flashed continuously but did not stay lit. The image is definitely way out of focus.

I think in your test you have fixed the AF point, most likely to the center AF point. In this case as soon as you half-press the shutter button, the camera informs you the AF point to be used by blinking it immediately. The actually focus is acquired only when the (same) AF point blinks again (and the focus confirmation).

But if you set the AF point selection to AUTO, there will be only one blink from the AF points to indicate who is in focus after you half-press the shutter button. That is the confusion.

That's just one way to defeat auto focusing. There are others. I don't know exactly how the user's older camera works, but as far as I can tell, lots of people make that mistake and blame the camera. There's a reason the green light is called a focus confirmation light.

ThrillaMozilla wrote:

I just checked. My Canon will blink red to indicate which exposure spot is active in the viewfinder, but that definitely does not indicate an exposure lock. It is quite possible to get that blink even though the camera is not focused at all.

Yes of course. But it blinks and beeps when you have AF lock.

You can get that blink even if auto focus is off, and even if it's not focused at all. I strongly suspect user error.

You can't take a photo in One Shot when you don't have focus lock.

I think you need to just read the manual and practice a bit to make sure you know how to use it.

I downloaded the first picture, with the brick building. Unfortunately, the image is so strongly compressed that I could not diagnose the problem with any certainty.

Nonsense. You do not understand JPEG compression, it does not cause such unsharpness.

Compression artifacts seem about equal to the image blur.

No.

The compression artifacts are so severe that I think that compression is a big part of the problem, but I think the image is also very out of focus. I suggest that you store your images at the highest quality.

ThrillaMozilla wrote:

brightcolours wrote:

ThrillaMozilla wrote:

I just checked. My Canon will blink red to indicate which exposure spot is active in the viewfinder, but that definitely does not indicate an exposure lock. It is quite possible to get that blink even though the camera is not focused at all.

Yes of course. But it blinks and beeps when you have AF lock.

Yes, I think the beep is a focus confirmation if you have it turned on. (I haven't tested to be sure.)

You can get that blink even if auto focus is off, and even if it's not focused at all. I strongly suspect user error.

You can't take a photo in One Shot when you don't have focus lock.

Good point. But you definitely can in AI Servo, for example. I see you already mentioned that.

I don't know how misfocusing due to user error is possible in live view, but I'm not ruling it out

Some lenses can't focus in live view (depending on camera model), like the Tokina 12-24mm f4 and the Sigma 18-50mm f2.8 EX DC. This is because they take too large steps, where the contrast never really is there, and the camera just judges that from one step to the next there was less contrast, so it takes a step back (into unfocus). But I had this issue with 3rd party lenses with the 450D, not with Canon lenses.

The OP, in the original post, did not mention live view focus though. I may have missed it in another post?

Also, in live view you can set the camera to use the PD AF sensor for focussing. That then will give the same results as normal OVF shooting.

I downloaded the first picture, with the brick building. Unfortunately, the image is so strongly compressed that I could not diagnose the problem with any certainty.

Nonsense. You do not understand JPEG compression, it does not cause such unsharpness.

Ordinarily, not with these camera images. But if not compression, then what caused this?

The softness is caused by misfocus. The squares by JPEG compression.

Ohrid's first photo

Notice the characteristic incoherence. I would say this suffers from extreme jpeg compression at some point in the chain. AnthonyL also mentioned this. It's probably also seriously misfocused. From the asymmetrical horizontal broadening of the flagpole, maybe also serious camera motion, or possibly loose elements in the lenses.

I still suspect user error, although camera malfunction can't be ruled out. Loose elements in the lenses could cause intermittent focusing problems. Ohrid, have the camera or lenses been dropped or received hard knocks?

ThrillaMozilla wrote:

brightcolours wrote:

The OP, in the original post, did not mention live view focus though. I may have missed it in another post?

Yes.

ohrid wrote:

As I tell camera most of the time takes good-focused shots, but sometimes happens such misses inspite af blinks red. I tested with Live view as you say. Result is the same. Mostly it is focused. But sometimes it is not focused.

And what do you think of the asymmetrical broadening of the flagpole and other vertical features? Compare it to the better-focused picture of the same building.

It looks like IS not having settled while the image is taken.