topic Re: Auto focus won't focus in EOS DSLR & Mirrorless Cameras

Auto focus won't focus

Cahoon38 — Wed, 21 Oct 2015 19:54:37 GMT

Hi all:

I'm just getting into my 70D and like it a lot. One thing that's happened twice lately. I was shooting a signature on a metallic object and the camera wouldn't take the shot. I figured there wasn't enough contrast and went to Manual and manual focus. Same thing, the camera wouldn't focus OR take the shot. BTW, the green dot in the view finder was blinking sigifying no focs. I then tried to overide it again by going to Bulb. Again, the same thing. I eventually fooled the camera by focusing on something close to what I wanted and then moved the camera and took the shot.

My question: how do you overide the AF - or can you?

Thanks to those that answer.

Re: Auto focus won't focus

cicopo — Wed, 21 Oct 2015 21:12:28 GMT

Turn OFF the switch on THE LENS. It's not done with a control on the camera.

Re: Auto focus won't focus

TTMartin — Thu, 22 Oct 2015 12:23:12 GMT

@Cahoon38 wrote:

Hi all:
I'm just getting into my 70D and like it a lot. One thing that's happened twice lately. I was shooting a signature on a metallic object and the camera wouldn't take the shot. I figured there wasn't enough contrast and went to Manual and manual focus. Same thing, the camera wouldn't focus OR take the shot. BTW, the green dot in the view finder was blinking sigifying no focs. I then tried to overide it again by going to Bulb. Again, the same thing. I eventually fooled the camera by focusing on something close to what I wanted and then moved the camera and took the shot.
My question: how do you overide the AF - or can you?

Thanks to those that answer.

Please read the manual for your camera. Being in Manual or Bulb mode have nothing to do with the focus settings of your camera.

Also be aware that lenses have a minimum focus distance. If you are closer to the subject than the minimum focus distance there is no setting on the camera you can change to make it focus. You can reduce the minimum focus distance of lenses with extension tubes, but, at this point I would just concentrate on learning to use the gear you have.

Re: Auto focus won't focus

ebiggs1 — Thu, 22 Oct 2015 13:05:26 GMT

"My question: how do you overide the AF - or can you?"

Depending on which lens you have it may not be necessary to turn off AF at all. Some Canon lenses have full time manual focus. So, all you need do is focus it yourself.

Obviously you were not at MFD if you were able to focus on something else and than take the shot. What lens are you using?

Re: Auto focus won't focus

TTMartin — Thu, 22 Oct 2015 13:21:43 GMT

@ebiggs1 wrote:

Obviously you were not at MFD if you were able to focus on something else and than take the shot.
Not obvious at all. If he was just under the MFD, and focused on something 'close', but, just over the MFD that would still explain what he experienced.

Regardless he needs to read his manual if he thinks changing to Manual or Bulb exposure modes impacts focus.

Re: Auto focus won't focus

ebiggs1 — Thu, 22 Oct 2015 14:13:19 GMT

"... he needs to read his manual ..."

Yes, agree that is the place to start but this is a forum where interaction is the base for its existence. A manual is not. If answering a person's question is a burden, don't do it. Sometimes it is more clear and makes more sense when you get a direct responce to a question. A different point of view if you will.

Don't you think the OP would have been somewhat lucky if he happened to focus on a object that was just in MDF and the intended subject was just out? MFD is not likely the cause, IMHO as usual.

Re: Auto focus won't focus

TTMartin — Thu, 22 Oct 2015 14:23:24 GMT

@ebiggs1 wrote:
"... he needs to read his manual ..."

Yes, agree that is the place to start but this is a forum where interaction is the base for its existence. A manual is not. If answering a person's question is a burden, don't do it. Sometimes it is more clear and makes more sense when you get a direct responce to a question. A different point of view if you will.

Don't you think the OP would have been somewhat lucky if he happened to focus on a object that was just in MDF and the intended subject was just out? MFD is not likely the cause, IMHO as usual.

The OP said he was shooting a signature on a metallic object. Signatures tend to be small and with a kit lens, getting it to fill the frame could very well put it below the MFD, that's why I brought up the MFD.

So I answered his question with a 'different point of view' AND suggested very politely that he read the manual.

Re: Auto focus won't focus

Cahoon38 — Thu, 22 Oct 2015 15:12:54 GMT

Hi again:

Seems like I stirred up some vitriol. I don't think I phrased the question as thorougly as I should have.

I did read the manual and got on Utube for instruction, but this was something not covered.

Anyway, I did find a way to fool the camera, so in tight spots I can always do that.

Thanks again for the replies

Re: Auto focus won't focus

TTMartin — Thu, 22 Oct 2015 15:51:53 GMT

@Cahoon38 wrote:

Hi again:

Seems like I stirred up some vitriol. I don't think I phrased the question as thorougly as I should have.
I did read the manual and got on Utube for instruction, but this was something not covered.
Anyway, I did find a way to fool the camera, so in tight spots I can always do that.

Thanks again for the replies

What do you mean by tight spots?

Re: Auto focus won't focus

Cahoon38 — Thu, 22 Oct 2015 16:09:02 GMT

I meant, when I get into a situation where the camer won't focus, I'll have to resort to "fooling" it.

The thing about this situation that pisses me off is that the camera won't allow a shot to be taken. If the green "out of focus" indicator comes on, then it doesn't allow a shot to be taken. Any camera should allow a shot to be taken even if it's overexposed or underexposed or even out of focus.

However, I have to say that I don't have a lot of experiece with the camera yet - and am comparing it to others I've had.

Re: Auto focus won't focus

TTMartin — Thu, 22 Oct 2015 16:15:34 GMT

@Cahoon38 wrote:
I meant, when I get into a situation where the camer won't focus, I'll have to resort to "fooling" it.
The thing about this situation that pisses me off is that the camera won't allow a shot to be taken. If the green "out of focus" indicator comes on, then it doesn't allow a shot to be taken. Any camera should allow a shot to be taken even if it's overexposed or underexposed or even out of focus.
However, I have to say that I don't have a lot of experiece with the camera yet - and am comparing it to others I've had.

When the camera's focus mode is set to 'One Shot' it requires that the camera confirm focus prior to the releasing the shutter.

When the camera is in AIServo mode, it will take the photo even when focus has not been achieved.

There is a AF/MF switch on the lens that allows you to change from Auto Focus (AF) to Manual Focus (MF). When in MF (Manual Focus) you can focus manually and take the photo regardless of the AF mode the camera is set to (i.e. One Shot/AIFocus/AIServo).

Even though you read the manual before, now that you've had some experience with the camera it would be a good idea to go back and read it again.

Re: Auto focus won't focus

Cahoon38 — Thu, 22 Oct 2015 16:39:22 GMT

Thanks much for your replies. I did turn off the AF on the lens before trying to manually focus and had no luck with that.

Actually, I shouldn't have posted a question in the forum before getting more experience with this particular camera.

Againk thanks for your attention.

Re: Auto focus won't focus

ebiggs1 — Thu, 22 Oct 2015 16:49:40 GMT

"Actually, I shouldn't have posted a question in the forum before getting more experience ..."

No actually it is OK to ask questions on this or any forum. Some folks just don't like to interact I guess. This forum and others like this are the places where you get the advice to gain the experience.

BTW, what lens is it? It may have a full time MF feature which means you don't have to 'fool' the camera. If you should happen to be at MFD that would quickly tell you.

Re: Auto focus won't focus

Cahoon38 — Thu, 22 Oct 2015 17:01:43 GMT

It's a 70D with the kit lens - EFS 18 - 135. I see that some disparage this lens, but in the last few days I've taken some very detaled pics with it, helped by the mirror lock up feature, which is great.

Re: Auto focus won't focus

ebiggs1 — Thu, 22 Oct 2015 17:39:18 GMT

Yes this is a good lens but certainly not a great lens. It DOES NOT have full time manual focus. Therefore do not rotate the focus ring while it is in AF mode.

Its MFD [minimum focusing distance] is 1 1/2 feet or so. Were you that close? If yes it could be as Mr. Martin suggested, you were too close.

[Mod note: Added verbiage just to clarify for a new photographer. Thanks for a great response as usual, Ernie! -Stephen]

Re: Auto focus won't focus

Cahoon38 — Thu, 22 Oct 2015 17:50:03 GMT

Ha, minium focus is 1 1/2'. I was a LOT closer than that!. However, this lens will focus at that distances much shorter than 1 1/2', but you gotta have enough contrast.

Anway, I suppose the real problems will start when I get into videos. LOL

Re: Auto focus won't focus

RobertTheFat — Fri, 30 Oct 2015 22:23:20 GMT

@Cahoon38 wrote:

Ha, minium focus is 1 1/2'. I was a LOT closer than that!. However, this lens will focus at that distances much shorter than 1 1/2', but you gotta have enough contrast.

Anway, I suppose the real problems will start when I get into videos. LOL

The minimum focusing distance is an absolute limit and is unrelated to contrast or anything else having to do with auto-focus. It is purely a function of optics and the design of the lens.

1½ feet is a pretty short MFD for a zoom kit lens. Usually you have to go to a true macro lens to do much better than that.

Re: Auto focus won't focus

TCampbell — Sun, 01 Nov 2015 01:06:43 GMT

Focus distance is measured from the image sensor -- not the front of the lens. There a focus mark on the body (it looks like a circle with a line crossing through it and will be printed on the top,of the camera body.)

If you thought you were closer than the MFD you might have been measuring from the front of the lens.