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On my Canon T7i, in the viewfinder, there is a circle that shows up when focus has been achieved. That is not functioning correctly now.

I am using it with a 24mm f2.8 Canon lens.

The focus indicator was initially not coming on at all. Then I realized if I focus on my pants it would come on. I then tried to focus on any other surface, all of which the camera easily achieved focus, but the indicator did not show. All the surfaces I focused on were flat and textured, very easy to focus on, but the camera was not searching for focus. It only showed the indicator when I focused on my pants.

Is it possible that either the camera or the lens is broken? Or am I missing a setting I can change?

scottbb
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Scorb
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  • This is not a duplicate question. In the one question the person already understands that AI servo mode prevent focus indication. In this question, the very question is why is the focus indicator missing. They are not the same. It is like asking "Why do my feet hurt" as opposed to "why does insufficient arch support hurt my feet". Up your game mods... – Scorb Feb 24 '20 at 02:41
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    The reasoning behind flagging duplicates or even near-duplicates is not any kind of "punishment" it is so more people can find answers to similar problems from a single Google search. It improves the long-term user experience by making similar topics more readily searchable via different routes/search phrases. – Tetsujin Feb 24 '20 at 12:13
  • If your question is: Why does AI-Focus choose to lock sometimes and not others...well, that is impossible to answer outside of a Canon AF developer...and we're fresh outta those on this site. – OnBreak. Feb 27 '20 at 06:38
  • Ya, according to the post.....it clearly is not the question LOL :0 – Scorb Feb 27 '20 at 19:30

2 Answers2

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If you have inadvertently changed the AF mode from "One Shot AF" to "AI Servo AF" then the focus confirmation light will not come on because the focus never "locks" but works continuously until the shutter button is fully pressed to expose the image.

If you are using "AI Focus AF" the system starts out in "One Shot AF" mode but can switch to "AI Servo AF" mode under certain conditions, in which case the focus confirmation light will not illuminate.

It sounds like you might be using "AI Focus AF" and the camera is shifting to "AI Servo AF" mode.

When in "AI Servo AF" mode (either by selecting it or by selecting "AI Focus AF" and allowing the camera to select it), the AF confirmation light will blink rapidly if the camera can not achieve focus.

Michael C
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To diagnose focus issues when shooting through the viewfinder as opposed to shooting live view:

  • Change AF/MF setting to AF
  • Turn off focus limiter in the lens, if any (24mm f2.8 does not have a focus limiter; long telephotos do)
  • Adjust the camera to use all focus points if shooting through the viewfinder
  • If the camera is equipped with "stop focus search" / "continue focus search" option when focus cannot be achieved, set it to "continue focus search"

The start focusing on things that are farther away than the minimum focus distance of the lens! Note that focus requires enough contrast. By having multiple focus points, chances that you have enough contrast are better.

Then after this you can test each focus point individually by separately selecting the used focus point.

By doing these tests, chances are you'll diagnose the focus issue: lens or camera. For example if some focus point does not work, it's the camera. If no focus point works, it may be the camera or a lens (try a different lens to make sure).

Try adjusting the aperture and taking a picture as well (preferably in manual focus mode so that not obtaining focus won't stop you from taking pictures). If you can't do these or if the aperture setting has no effect on exposure, the camera-lens contacts may be faulty and require cleaning.

Do note if the lens is searching for focus at all. Usually when you can't achieve focus, the lens may be hunting for focus and you should be able to note this in the viewfinder.

It may be the case there is some fault somewhere and the camera confirms focus only if it's already in focus. This may explain why you could focus on your pants.

juhist
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