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Canon t5i slow continuous autofocus

UnknownUser
Apprentice

I've recently bought a new Canon t5i camera with the kit lens for creating YouTube vlogs. However, I've noticed the autofocus is so slow I can't even use it since 90% of the time it's just out of focus. I have the camera pointing at a large park with people walking past and then turn the camera to my face and it's out of focus and it stays out of focus until I stand still for 3-4 seconds, but then as soon as I start walking, the camera can't keep up with the focus.

I usually record at f.8 with 1/60th shutter speed and I just leave the iso to automatic.

 

I'm sure I'm doing something wrong and I would love some feedback and help.

1 ACCEPTED SOLUTION

I am not familiar with video performance with that camera, but what you describe sounds like the camera is functioning normally, albeit rather poorly.  In my book, it doesn't autofocus when shooting video.

Some newer models have "Dual Pixel AF CMOS" sensors, which are very good at focusing during video modes.  

 

http://www.dofmaster.com/doftable.html.  

I keep mentioning DOF, but I sense you may not be familiar with the term.  That table and web site is a good illustration of what DOF means, and provides calculators to estimate performance.  Your camera is not listed, so use they Canon 7D, because it has the same size sensor.

A lens has perfect focus at one distance from the lens, and vertical plane.  As you move away from the plane of perfect focus, the subject starts to become blurry.  Small variations in distance are nearly indistinguishable to the eye.  Larger changes in distance eventually become unacceptably out of focus.

Depth Of Field, DOF describes the range of distances that have "acceptable focus".  Notice how a narrower aperture gives you a greater DOF.  Notice how a shorter focal length gives you a shorter hyperfocal distance, which describes the distance where everything seems in focus.

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"The right mouse button is your friend."

View solution in original post

7 REPLIES 7

Waddizzle
Legend
Legend

What lens are you using?  The problem could be your lens, and other camera settings, such as AF mode.  Make sure that you are not inside the minimum focusing distance of whatever lens that you are using. 

I do not believe that model can automatically track and focus on faces.  You must manually select an area to focus on.  In fact, do not ever let the camera select an AF point for you, not even when shooting stills, not unless you're shooting action photography, which is a whole other can of worms.

 

You may be better off using manual focus and an ultra wide angle lens with a focal length less than 20mm.  Look up the phrase "Depth Of Field".  With a lens with a focal length in the mid-teens, you can set the lens for its' hyperfocal distance, and everything beyond a couple of feet will be in focus.  

--------------------------------------------------------
"The right mouse button is your friend."

EF-S 18-55 mm f/3.5-5.6 IS STM Lens

I have the EF-S 18-55 mm f/3.5-5.6 IS STM Lens, the camera is always a foot or more away from my face and yes, the camera does support face tracking.

The problem is I would really hate to use manual focus because for me readjusting the focus every few seconds does not look good at all with the video.


@UnknownUser wrote:

EF-S 18-55 mm f/3.5-5.6 IS STM Lens

I have the EF-S 18-55 mm f/3.5-5.6 IS STM Lens, the camera is always a foot or more away from my face and yes, the camera does support face tracking.

The problem is I would really hate to use manual focus because for me readjusting the focus every few seconds does not look good at all with the video.


Great, if the camera can support face tracking.  But, the camera still needs to be told, or directed, what to track.  What focal length are you using?  You just might need a camera operator.

As far as "readjusting the focus every few seconds" goes, you need to learn about, and understand, DOF, Depth Of Field.

--------------------------------------------------------
"The right mouse button is your friend."

Mr_Fusion
Enthusiast

My initial reaction is the lens. 

 

Can you hear the lens motors when you're trying to focus? Check it in a quiet room, holding it near your face or ear. Press the shutter button half way and hold it there. 

 

Is the lens set to AF or MF? Try moving the selector in case it is not properly seated.

 

Is the STABILIZER (IS) turned on or off? If you are using a tripod or sitting it on a desk, turn it off. 

 

Have you tried a different lens?

 

How long does a fully charged battery last? Overworked focusing motors will run down the battery faster. 

 

How fast does it focus for still pictures?

 

A test is to remove the lens (put the caps on either end). Give a firm yet mild shake, holding the caps, close to your ear. Is there any rattling like something is loose? The most you should hear is a slight whirring sound of air. There should be no rattles. 

 

While the lens is off, look at the contacts for both the camera and lens. Is there any obvious loose contacts, any foreign matter, or even a contact that looks different from the others? DO NOT touch the contacts on either the camera or lens with bare fingers. If you see foreign matter on a contact, gently clean the contact with a cotton swab wet (not soaked) with isopropyl alcohol. Hold the lens and camera upside down so any debris falls out, not into the body.

 

Are the focusing ring and zoom ring stiff to turn? (The focus ring is the further out and narrower ring. The zoom ring is the big ring in the middle of the lens) Both should turn freely, but with a small resistance. Neither ring should make a sound as you turn them.

 

And a silly check; but is there anything that might be restricting the lens barrel from turning? That could be a stiff hand, part of the holder or whatever the camera is resting on, etc. The lens should not rest on anything and be free to turn. (Your right hand should hold the body and the left hand the zoom ring.)

 

The minimum focusing is around 8 or 9". Sometimes, when you are close to the minimum range, the camera will be hunting to find the proper focus. You would hear the focus going back and forth looking for a sweet spot. A suggestion would be to try at a minimum of 15" and see if that makes any difference.

 

The 18-55 is not a bad lens. However, it is a bottom line lens and can fail or even just be quirky. Try those checks above and you will have a lot more information to narrow it down.

 

Good luck.

I've tried out all the techniques you have asked and here are my answers:

 

-The lens motors are very quiet, but I can hear them moving.

 

-When the camera is moving about, it's set to AF, however, when it's still, I set it to MF. And I have tried to move the switch in case it was not seated properly, but it would not move anymore so I take it it's in the correct position.

 

-The stabilizer is on, I'll also turn it off when it's on a tripod or something.

 

-Unfortunately, I only have one lens.

 

-Although I cannot give an exact time, I can say it does last quite a lot, I can usually last a full day, that being with videos and photos.

 

-Still, pictures take around 2-4 seconds. It's depending if It's focusing on a small object or something large.

 

-I've tried a little shake on the lens, I can't hear anything rattling.

 

-I've checked both the camera and the lens contacts, everything looks OK.

 

-The lens and the zoom rings are very easy to turn. Like you said. I can turn them with very little force. And no, they don't make any sounds.

 

-Nothing is restricting me from moving any of the rings, I have the camera on a small hand held stabilizer when I'm walking, and when I know I will be setting down the camera for a few seconds, I have a bendy tripod on it.

 

-To be honest, I find no difference on how far my face or object is away from the camera, it takes a few seconds to focus and as soon as I move it around it's no longer in focus.

 

As for focal length, It's nearly always on 18.

I am not familiar with video performance with that camera, but what you describe sounds like the camera is functioning normally, albeit rather poorly.  In my book, it doesn't autofocus when shooting video.

Some newer models have "Dual Pixel AF CMOS" sensors, which are very good at focusing during video modes.  

 

http://www.dofmaster.com/doftable.html.  

I keep mentioning DOF, but I sense you may not be familiar with the term.  That table and web site is a good illustration of what DOF means, and provides calculators to estimate performance.  Your camera is not listed, so use they Canon 7D, because it has the same size sensor.

A lens has perfect focus at one distance from the lens, and vertical plane.  As you move away from the plane of perfect focus, the subject starts to become blurry.  Small variations in distance are nearly indistinguishable to the eye.  Larger changes in distance eventually become unacceptably out of focus.

Depth Of Field, DOF describes the range of distances that have "acceptable focus".  Notice how a narrower aperture gives you a greater DOF.  Notice how a shorter focal length gives you a shorter hyperfocal distance, which describes the distance where everything seems in focus.

--------------------------------------------------------
"The right mouse button is your friend."

 

If it was the camera then I would expect some, or even mostly out of focus still shots. If it was the lens then I would expect more noise, manual turning resistance, and battery drain. 

 

I tried some things on my wife's T6i and 18-55 IS II lens. The focus will hunt whenever I move the camera, but it is near instantly. To go from focusing near my feet (6 feet) to the treeline (75 feet) takes about a half to 3/4 seconds. Now, I'm looking through "Live View" while this is happening. I can see how shooting a video with a 2 to 4 second delay would be very frustrating. Also, the lens motors just might be picked up by the audio if you use the camera mic.

 

One thing to remember when focusing at distant objects, the smaller they are or closer they blend into the scene, the harder it is to pick them up. Also, the Rebel line likes a lot of light to autofocus. The camera uses the contrast of the subject to its background in order to focus. The less contrast, the harder it is to find the subject.

 

Unless someone else can see a problem or suggest a solution, I would suggest you call Canon Support about having the camera and lens serviced. Hopefully they are still under warranty.

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