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Green/Red Focus Box Missing and Flicker/Flash on LCD




1) I recently reset my T3i and can't figure out why the center focus box that turns green or red isn't performing as it used to. When I depress the shutter button for AF the box is there but doesn't turn green or red. It also used to stay on the LCD as green as I took the picture which isn't anylonger as well.


What happens now is it does its focus thing without turning colors and then snaps.


2) Also, all info on the screen disappears when I snap. All info meaning the grid I have up, the focus box and all other info ie. histogram and settings that are on the left side of the LCD. If I recall correctly, all info stayed on screen including the focus box green or red.


3) Lastly, the focus box will flash green when I snap the shot but that only happens "sometimes" and not always.


4) One other thing I noticed too is as I depress the shutter button or snap the shot I get a pink flicker on the LCD which wasn't happening before.


Any ideas how to fix these issues?


Thanks in advance.


Rising Star

Too many problems occurred at the same time, so the best you can do at this stage is to :


1. reset the camera to default setting and clear all camera settings and clear all custom function ( inside the menu, different tabs)

2. format the SD card or if you have, use another one, format it before use

3. test with another battery, fully charged or recharge the battery if you don't have another one

4. use another lens (may be not relevant but it won't hurt)

5. if it doesn't work, try re-instal or update the firmware on the camera


after each one of the above steps, test the camera


6. if problems persist, call Canon for advise/price quote


BTW, check if you have changed the AF from live mode to quick mode or did you have enabled mirror lock up etc.

Thanks, I'll try doing those options. I did however, reset via the 2/3 methods which is when I believe this all started as well as change the battery which also is when it all started. I will it all again and see.


As far as a lens, I have but they aren't canons or compatible with electronics on board. They are full manual analogs if you will.


Regarding the card, it's been in the camera now for months upon months. I assume it can get corrupted somehow and I'll try but I don't believe it would be the card...but again, I'll give it a shot and try another one.


Updating the firmware is a bit of a pain for me/this camera because I am running a mac OSX 10.5.8 (PPC) and I don't think the sofware is compatible. I looked online and find it's all Intel based Macs. I have to load the card into a Canon camcorder I have in order for the card show up as a drive and for me to update the firmware (if I recall correctly that's how I had to do it).


If you know where I can find the software for the camera that runs on PPC 10.5.8 I would be grateful for a link.


Once I do all the steps (in some time) I will followup...


Thanks much.


Rising Star

according to your description, you shoot mostly with liveview mode. please cycle the info button to see if there is difference.(regarding your #2 problem)


is auto focus normal in Standard Viewfinder Mode ( not live view mode) ??

Thanks. I believe I've tried that too as well as switching live view options ie. live view 1, 2 and quick. If that isn't the right one you are referring to, please direct me to which setting you are meaning.


Also, I just took a look through the eye piece and have also noticed that the focus area spot meter (if I am calling it correctly that looks like...



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    .          .        .

         .          .



isn't the same either. The dots blink when in focus BUT they are fine dots they are very very blurry now and relatively large soft spots vs. a sharp pin point as it used to be. They don't seem be focusing on multipoints nor do they change and blink as I move the camera with the shutter button partially depressed. Before, I believe all lights would light up as I moved around.


I'll give all potential solutions a try and see. Thanks.



If the focus points in the viewfinder are blurry then it means you need to adjust the diopter on the viewfinder.


On the upper-right corner of your viewfinder, there's a tiny little wheel.  That wheel allows you to adjust focus for your eyes e.g. if you normally wear glasses, it can correct for diopter adjustment as long as it's in the -3 to +3 range (and the vast majority of people are).  If you need corrects outside that range, Canon sells slide-on diopters that can go even stronger.


Anyway... to adjust it:


1)  Point the camera at something with no contrast... such as a plain white wall... or a solid blue sky, etc.   

2)  Not required, but I actually think this is easier if you deliberately de-focus the lens -- just put it well out of focus and leave it.

3)  Now look through the viewfinder at those focus points and adjust the tiny wheel in the corner until the focus points are as crisp as possible.  


The viewfinder is now focused for YOUR eyes.  That means when something appears to be sharply focused, it actually is sharply focused.  


At this point you should be able to switch on the camera, look through the viewfinder, let it auto-focus on something... and it should look sharp.




As light enters the lens, there's a specific distance from the front of the lens to the focus plane.  There's a special mark on the top of the camera and on your T3i it's left of the hot-shoe ... over by the support ring for the neck-strap on the left side.  The mark looks like a line... with a circle in the middle of it.  That mark indicates the position of the focal plane (the sensor).   When the lens is focused... it's focused to THAT distance.  


When the reflex mirror is in the "down" position, it bounces light up at a 90º angle into the pentaprism.  But more specifically it's bouncing the image onto the "focus screen".  If you remove the lens and look at the top of the camera you will notice a frosted piece of "glass".  The distance from front of lens, to mirror, to that "focus screen" is EXACTLY the same as the distance from front of lens to the sensor (when the mirror swings clear.)


This means what you're REALLY doing is projecting the image onto that bit of frosted "glass".  You can think of it as a mini "rear projection" movie screen.    


Even if the image is tack-sharp on that screen... if your viewfinder diopter isn't adjusted for YOUR eyes then that image would still look a bit blurry.  Once you finish adjusting the diopter you'll be able to trust it.


BTW, I noticed your post is about the "green/red" box which implies you may be relying on the live-view display.  When you use live-view on your camera it uses a completely different focus system then when you look through the viewfinder.  The focus system used when you look through the viewfinder is MUCH FASTER than the focus-system used in live-view mode.  If you are having issues with focus speed and delays when trying to take photos... switch to using the viewfinder and it'll be much faster.


Tim Campbell
5D III, 5D IV, 60Da

Diopter was adjusted, the image is clear, the focus point squares are clear, the little red led lights aren't. I actually did focus on a white wall and many other things to test it. 


Overall, my eyes are fine the rest isn't :).


Re: using the viewfinder vs. the LCD...yes, the view finder is faster I understand/know and use it which is how I was able to detect the red led issue.


The images are fine, they come out clear/in focus. it's the AF box indicator, screen flicker and view finder red led's that are the problem. It seems to be a display issue that seems to involve a portion of the electronics of the cam.



@mut wrote:

Diopter was adjusted, the image is clear, the focus point squares are clear, the little red led lights aren't. I actually did focus on a white wall and many other things to test it.  


I'm a bit confused... when you say "littel red lights" are you referring to the black AF points that light up red when they're active or blink when they lock focus?



Tim Campbell
5D III, 5D IV, 60Da

Yes..that's what I am referring to. Those red lights don't seem to be operating as they used to also. If I recall correctly they were sharp/very clear red dots. They are now larger and soft. So soft they are barely visible.


This is in addition to the other display related issues on the LCD where the focus box that turns red/green doesn't stay on the screen once it focuses nor does it turn green or red when it's done focusing. When it's done focusing all overlays disappear/turn off. The only way I know if it is focused or not is by depressing the shutter will or won't take the shot. 


If I recall correctly all info stayed on the screen throughout except when the shutter activated and took the shot which a quick black flash would happen.

Now if diapter is adjusted and solved some of the problems and images are clear and looks focusing right, I need you to check one more thing.


Check the focus screen - have you ever messed with it and is it now installed properly on the mount. This may be the cause of the blurry AF points(red led lights as you have described) Check the manual for details. There may be some Youtube tutorials about focus screen installation. It won't solve the AF box in LV problem though.


I still believe that screen flicker is an indication of electronic failure. (or nearing end of life cycle)


If anything cannot help to resolve the problems, you either have o live with it as it or send to canon service center to diagnose the cause. Now they take a flat rate for service/repair. I guess it costs around $200 plus shipping and more $$ if the parts cost more than the flat rate.


I used to have one but sold it 2 years ago. My older 40D still survived. Rebels seem to be less durable to me. (just to me, there are still surviving XT and XTi of course)



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