10-09-2013 03:53 PM
This is a great set of videos that will help you understand the Canon autofocus system. It's in 3 parts.
These are presented by Canon's Rudy Winston.
If the lighting is particularly low or the subject lacks contrast (e.g. plain surfaces) or both then the camera will have a more difficult time locking focus. It can more easily lock focus if it is using the center point or allowed to use all points then if it's just using one of the points around the periphery of the frame (on a T3i and earlier cameras -- because only the center point is a "cross type" point on a T3i and the periphery are all single-axis points. This is not true of the T4i, T5i, 60D, 70D, or higher end bodies.)
If you want to "test" the auto-focus system to make sure it's working correctly, give it a high-constrast target (e.g. a sheet of newsprint works well) in _excellent_ lighting.
11-25-2013 09:48 AM
I was following your question because I'm having the exact same issue. I am a mother of 2 little boys and have a Canon Rebel T1 EOS that i've been using for about 3 years to capture my boys. I always use automatic mode and have loved this camera for it's quality photos, but suddenly the other day it did the same thing yours did....just stopped shooting. says busy...sounds like it's trying to focus but won't shoot. and will shoot inMF mode. I didn't drop it or damage it in any way and of course am now out of warranty. I know if I take in for service it will likely be $100s and I"m wondering if I may be better off buying a new bundle. i think it's rediculousto have to consider that after only 3 years but i suspect these just aren't built to last anymore and my money may be better spent on new stuff. Have you taken yours in yet? if so what did they say?
I'm also in limbo like you and missing moments without my good camera around.
Thanks for your input.
11-25-2013 10:35 AM
laurac, if your camera _will_ take a photo in MF mode but will not in AF mode then it usually means the camera is not able to lock focus.
There can be a few reasons:
1) Not enough light -- test your camera in an exceptionally well lit shooting circumstance and see if the issue goes away. E.g. shooting outdoors during the daytime, etc. would certainly be enough light to focus. A camera will typically struggle to focus in dim/dark settings. The choice of lens can also make a difference since some lenses collect substantially more light than others.
2) Low contrast target -- a camera will typically struggle to focus if the subject (specifically the points on the subject where the auto-focus points are attempting to focus) are bland. Plain walls or plain blue sky, etc. can lack enough contrast for the focus system to work. The phase-detect focus system on the camera is a bit like taking a photo, printing, then cutting the image into two halves... now slide one half slightly out of alignment (out of phase) with the other half. The camera is basically comparing the pixels along the edges of the two "halves" and when the patterns match, it's focused. That's basically the short version of how phase-detect auto-focus works... except the sensors are only looking at small areas of the scene... not the entire scene.
3) Lens malfunction -- the focus motors are in the lens itself. It's possible to have a focus problem that only occurs with one specific lens... but another lens works fine. If you have another lens to test, I suggest swapping lenses and testing.
It is possible that it's the camera itself... but that's actually fairly unlikely. The #1 reason (not enough light) is usually the culprit (this will happen to a camera in perfect working order.)
Incidentally your camera does actually have two separate focus systems. If the phase-detect AF system is not working, switch to "Live View" mode on the camera and try again... that system uses "contrast detect" AF rather than "phase detect" AF. It is a COMPLETELY different system. e.g. if there were a problem with your phase detect sensors then it would not impact the contrast detect system (the contrast detect system is not nearly as fast and may need to "hunt" for focus... so the phase-detect system is preferred.)
11-25-2013 11:01 AM
Thank you for your reply. I created a new post with my question to the forum since I didn't know how this worked. I do not have an alternate lens to switch to so can't test that but have tested lighting and can manage to capture a rare shot if i set up perfect circumstances outside with a contrasted target.
I know there is some malfunction that needs repair because as i stated before I've been shooting with this camera for 3 years in all types of lighting without any difficulty. I'm really just trying to decide if this worth paying to repair or am I better off putting my money towards a new camera bundle. It's very disappointing to me that such an expensive camera isn't working after 3 years of gentle use, but i hate to pour more money into a problem that might persist.
12-05-2013 08:53 PM
Same exact issue for me. I've had mine for just over one year!
EOS Rebel T3
My camera no longer takes (clear) pictures in AF, using any of the basic zone modes or other modes. I've tried in good lighting. The flash flashes sporadically, it attempts to adjust (by making clicking noises), a little green circle flashes in the lower right hand corner and ultimately either a blurred picture comes out or it doesn't ever click a picture.
Basically, the same exact issues as the previous two.
12-05-2013 09:56 PM
Whenever someone experiences this issue, I suggest performing a few tests:
1) Switch the lens to the "MF" (manual focus) mode (don't use "AF") and just see if it will take a photo.
2) Switch the lens back to "AF" (auto-focus) BUT... use the "Live View" feature to take the photo (compose the shot using the LCD screen preview instead of using the viewfinder.)
If the camera WILL focus and take the shot in "Live View" mode, but will NOT take the shot in normal mode (using the viewfidner), then this is probably an indication of a problem in the camera body with the phase-detect focus sensors. In this case, it's probably the camera body that needs service.
If the camera will NOT focus and take the shot either while looking through the viewfinder (normally) or in "Live View" mode, but WILL take the shot if you switch the lens to "MF" then this is a likely indication that the focus is malfunctioning in the lens itself (not the camera body). In this case the camera body is probably fine, but the lens likely needs service.
The camera has two independent focus systems... a "phase detect" system (using special sensors on the floor of the camera) as well as a "contrast detect" system which uses the main sensor to find focus. If both systems fail, then it's likely that a malfunction of the lens is to blame (the focus motors are always in the lens on Canon EOS lenses). Conversely, if either focus system can reliably work but the other failes, then it's an indicator that the lens' focus motors are probably fine, and the issue is likely isolated to a fault in the camera body -- hence the body needs service.
Since all the "moving parts" are in the lens and not the body... most of the time when this happens, it's the lens (this assumes there is plenty of light... if there's simply not enough light then all modes can fail but this would not be an equipment defect.)
12-17-2013 10:09 AM
If swapping to another lens works, at this point the original lens you were using will need to be evaluated by our Factory Service Center.
To start the service process, you'll need to complete a Repair Request on our website.