20D backfocuses like crazy. Help!

[picturesque]

OK--putting the focus point on the face is not good. The actual focus points are larger than the red squares would suggest, and the red squares are not always centered on the focus point it is supposed to represent. As I mentioned, I found that my center focus point is actually slightly below the red square.

 

Back to not focusing on the face--unless the face is very large in the frame, the focus point (the actual one) goes beyond the outline of the face (it is bigger than the red square) and gets snagged onto the writing on the background. This may not happen if you have a smooth, non-contrasty background, but the minute you do, the focus invariably goes for the contrasty. On shots like this, assuming they go down to the waist, try lapel edges, neckline edges, or even belt buckles, but be careful of smooth, no contrast areas around them.

 

Re the * button. The way to use this is to focus on a good target and let go of the button. Maybe focus twice on the same target. Quickly check the distance scale on the lens to see if it is way off. And, in a situation like you had, repetitive shots of subjects with the same subject distance--focus once, zoom in to be sure the focus is correct, and then leave the focus where it is for the rest of the shots. This, of course, assumes some DOF margin of error (not a wide open aperture). I used to shoot bar mitzvah candle lighting shots like this, because the 20D would get tangled up ont he candle sticks in front of the subject.

[larry schaefer - chicago,]

My response is not technical in any way. I solved my deplorable Canon focusing issues by unloading all my Canon gear Rebel XT, 20D, and a 40D and replacing them with used D70's. Most people do not have the opportunities to do extensive physical equipment comparisons.

[picturesque]

Larry--I've used a few digital Nikons, and while the 20D definitely has flaky focus, the Nikons weren't perfect either. Part of the problem is inherent in autofocus--of any kind. Some of it is inherent in focusing (manual or auto)--of any kind.

 

Anton--where did you get the 16-35mm? If you bought it used, it could be a dented part in the lens. That's what happened to my lens, and the problem was bad focus, period, although if the lens is OK with other cameras, that isn't it.

[keith reeder]

"My response is not technical in any way. I solved my deplorable Canon focusing issues by unloading all my Canon gear Rebel XT, 20D, and a 40D and replacing them with used D70'"

 

Meh...

 

One of the reasons I dumped Nikon and came to Canon was *very* poor AF consistency from the D200.

 

The 30D was *much* better, in my experience.

[keith reeder]

To which I'd add: the 40D is in another league again, and 40D "AF problems" are unlikely to be down to the *camera*...

[William Michael]

> WW, can you tell me which one are you referring to? At different times I tried using everyone of them with no [visible] differences and last time I put it in AE lock/AF (2). Could I have been mistaken? <

 

This sentence is the key to unlock the problem IMO.

 

I have interrogated the EXIF data of the two images you have posted.

 

Please confirm the shooting mode used for these images, this is critical to the question.

 

My EXIF interrogation is reading that an `auto exposure programme` was used, most likely that means `Full Auto` was selected.

 

If this is the case, then the camera, by default, will be using Automatic AF selection point.

 

It will automatically choose what it thinks is best AF points to use, for the shooting conditions and this overrides the C.Fn.4 setting.

 

Thus, if I my EXIF interrogation is correct the white wall would have been chosen by the outer AF points, almost all of the time, in this shooting scenario.

 

WW

[allen_staley]

Anton, I can simpathize with you! My wife and I have a small part-time portrait sudio. Last year we both had Canons Rebel XT and 20D. We both had the same problems. We almost lost our reputation because both was doing the very same thing. We fought with it for nearly a year trying all sorts of lenses and etc. We even sent the Rebel back for warranty work and it worked for a month or so and back to the same thing. I had another professional friend with a 20D and he had his back to the factory 3 times for the same thing. What we did to totally fix the whole thing was sell both outfits totally and switch to Nikon D80 and have never had one more problem after over 5000 images NOT EVEN ONE has been out of focus due to camera fault!

[thomas_hardy1]

I have a 20D and have not had one problem (for 3 years) until yesterday. I was

taking a group portrait and was using the 28-135 lens with a 430ex flash. I took 4

images and in each one the faces were very soft.

 

I was shooting at 28 mm, 1/60 at f/5.6 with flash set to give good exposure

(bounced) according to the histogram. The focus point was on the body of one of

the subjects, and I was standing far enough away that DOF should have helped

more. I thought maybe the flash had something to do with it.

 

I'd like to know what happened.

[antonshmerkin]

WW, here is dataon the BAD image:

 

Camera Model

Canon EOS 20D

Shooting Date/Time

28.05.2008 1:45:03

Shooting Mode

Program AE

Tv( Shutter Speed )

1/60

Av( Aperture Value )

4.0

Metering Mode

Evaluative Metering

Exposure Compensation

0

ISO Speed

1600

Lens

24.0 - 70.0 mm

Focal Length

67.0 mm

Image Size

3504x2336

Image Quality

RAW

Flash

On

Flash Type

External E-TTL

Flash Exposure Compensation

0

Red-eye Reduction

On

Shutter curtain sync

1st-curtain sync

White Balance Mode

Color Temperature(5400K)

AF Mode

One-Shot AF

Parameters Settings

Contrast High

Sharpness High

Color saturation High

Color tone +2

Color Space

Adobe RGB

Noise Reduction

Off

File Size

8384 KB

Custom Function

C.Fn:01-0

C.Fn:02-1

C.Fn:03-0

C.Fn:04-0

C.Fn:05-0

C.Fn:06-0

C.Fn:07-0

C.Fn:08-1

C.Fn:09-0

C.Fn:10-0

C.Fn:11-0

C.Fn:12-0

C.Fn:13-0

C.Fn:14-0

C.Fn:15-0

C.Fn:16-0

C.Fn:17-0

C.Fn:18-0

Drive Mode

Continuous shooting

Owner's Name

unknown

Camera Body No.

0520200319

 

And here is data on the GOOD image

 

_MG_0001.CR2

Camera Model

Canon EOS 20D

Shooting Date/Time

28.05.2008 1:08:48

Shooting Mode

Program AE

Tv( Shutter Speed )

1/60

Av( Aperture Value )

3.2

Metering Mode

Evaluative Metering

Exposure Compensation

0

ISO Speed

1600

Lens

24.0 - 70.0 mm

Focal Length

43.0 mm

Image Size

3504x2336

Image Quality

RAW

Flash

On

Flash Type

External E-TTL

Flash Exposure Compensation

0

Red-eye Reduction

On

Shutter curtain sync

1st-curtain sync

White Balance Mode

Color Temperature(5400K)

AF Mode

One-Shot AF

Parameters Settings

Contrast High

Sharpness High

Color saturation High

Color tone +2

Color Space

Adobe RGB

Noise Reduction

Off

File Size

7889 KB

Custom Function

C.Fn:01-0

C.Fn:02-1

C.Fn:03-0

C.Fn:04-0

C.Fn:05-0

C.Fn:06-0

C.Fn:07-0

C.Fn:08-1

C.Fn:09-0

C.Fn:10-0

C.Fn:11-0

C.Fn:12-0

C.Fn:13-0

C.Fn:14-0

C.Fn:15-0

C.Fn:16-0

C.Fn:17-0

C.Fn:18-0

Drive Mode

Continuous shooting

Owner's Name

unknown

Camera Body No.

0520200319

[picturesque]

Anton--I repeat my post above re not focusing on faces if the face isn't the majority of the frame (and the rest of it, too). Also--did you get the 16-35mm lens used?

 

I would do some test shots with difficult situations for the camera/lens to see if this different technique works for you.

[William Michael]

Thanks, Anton.

 

I am constructing my response, but I am pushed for time, but will return later . . . In the meantime, I refer to:

 

> I am going to listen to WW some more - looks like he knows what he is talking about. <

 

Do not exclude others whom are very knowledgeable, Especially Nadine Ohara.

 

It might appear we have different points of view on this matter, But I know Nadine and I have a very similar point of view, but just a slightly different methodology. We are both seeking information to help you.

 

In regards to my slightly different methodology, specifically about focussing on the face:

 

I am not arguing with Nadine on this point, where she writes: `putting the focus point on the face is not good. The actual focus points are larger than the red squares would suggest . . .etc.

 

I think I have a good understanding of my 20D, and so does Nadine of hers, I am sure of that.

 

It was from reading her posts on this issue originally, that drove me to test my 20D and the AF ruthlessly so I had a better understanding of it.

 

What I am saying is, in regard to the images provided I would have first focussed on the man`s eye, but the important sentence I wrote was: ` focused and confirmed on the man`s eye` CONFIRMED, is very important.

 

What I mean here is, in a quiet environment I can here the AF motor, nonetheless. I watch through the viewfinder, and would have first focussed on the back wall and moved the frame of the 20D across the face to find an HIGH CONTRAST AREA and watched the AF confirm on the eye. So that might have been three or four pushes of the `*` to establish what the AF is `seeing` in that particular scene.

 

Then: IF the face / eye did not have enough contrast, or was too small in the frame, I would have gone for a shirt collar, shirt on the chest area etc.

 

I think Nadine and I are saying the same things: I too use belts, collars and feet / shoes: it was just with this particular scene I think there was enough of the face in the frame and enough contrast on it to use it: but CONFIRMING the focus is a critical step.

 

Re read what Nadine wrote and do some tests as she says, and answer the question about the lens

 

(BTW: I think the lens used is the 24 to 70, not 16 to 35?).

 

I`ve gotta go, I will post another (more technical) bit latter.

 

WW

[antonshmerkin]

WW, thanx again! By no means I intended to deminish the weight of Nadine's massage by referring to you as a "knoledgeble one"!))) I've studied her posts as well as yours very carefully and think you both are great! So, with that out of the way let's get back to AF. First off, I noticed the backfocusing problem does not go away in MF. Thats right, in manual focus (one shot) I put a centerpoint on the subjects face, the red square blinks and sounds off confirming focus and yet the image may very well apear blurrier then the background. It happened before. Thanxs for the tip on confirming focucs in AF - I havn't done that. And finally, the funny thing about belts and collars is that AF sharply focuses on those leaving both - the face and the backgroound out of focus. Not during this shoot but I've heard that suggestion earlier and tried it. Weird.

[antonshmerkin]

WW, and yes, I bought all my L-glass brand new. Although, I bought the body off a guy who showed me a receipt from an online store that was like a month or so old. I saved about $200 on that deal back in 2004

[William Michael]

Sorry for the delay, I had a very busy weekend.

 

At this point I want to outline the exact procedure I would use. But having read your last post other things have entered my mind, like, why did the man wish to sell you the 20D: did he have an accident with it and has failed to tell you about that?

 

Nonetheless referring to the custom functions:

 

1. Set C.Fn-04 to 1 (AE LOCK / AF)

 

This places the activity of the AF to the `*` button, provided the camera is AWAKE. If the camera is not AWAKE, you need to half depress the shutter button to wake it up.

 

Each time you press the `*` the camera will focus. Once it achieves focus it stops. If you want to re focus you need to take finger pressure off the `*` and re depress it. This last point is very important, as it must be remembered that the camera `Achieving Focus` does not mean that it is focussed on what you want. It is important to note that the red squares are not accurate representations of where the focus points actually are.

 

2. Set the AF point selection to the middle point only.

 

I have C.Fn-13 to 1 (Multi Controller Direct) so I can easily change the AF point with my left thumb.

 

 

3. Set the AF to ONE SHOT

 

 

4. With those functions set I would have focussed on the man`s eye, and confirmed that focus, as I previously mentioned. As I also mentioned earlier, I am not arguing with Nadine on this point, and I have explained in detail those matters, but remember you need HIGH CONTRAST AREA and watch the AF confirm the focus.

 

5. Once focused, the camera should hold that focus point throughout multiple uses of a single shot shooting sequence (multiple shutter depressions) or throughout the shooting sequence of continuous shooting: thus allowing easy focus and recompose.

 

In fact the lens should stay at that focus point until the `*` button is pressed again, even if he camera is powered down and powered back up.

 

***

 

I hope that assists, but I think there are now another element to consider, like has the 20D had an accident.

 

If we assume the camera is faulty: then consistently and accurately rechecking the focus using the above method for all your shooting, you will get whacky results with all lenses, and that would be a strong indication that the camera is faulty.

 

If we assume that the lens is faulty: you need to isolate the problem to this single lens. One way of doing that would be to always follow the procedure above for your shooting method and note the results. If you get consistent focus with your other lenses and not with the 24 to 70 then it is the lens and it is most likely faulty.

 

If we do not assume your lens or camera is at fault, but it is `operator` error: then one simple explanation for the results on this thread is:

 

In the scene mentioned, with Cn.F,4 = 0, we must remember that every time the shutter button is depressed the lens will refocus.

 

This means that even though you might have achieved focussed on the face INITIALLY, if the shutter button is released from the half depressed position the lens will refocus on a new point. OR as previously mentioned the focus might not have been achieved on the face at all in the first instance.

 

It just might be that in the passion of the shooting, whilst you are considering all the other aspects of recomposing the shot, and capturing the expression of the subject, you do not notice that release of pressure on the trigger and the subsequent refocus on the white wall.

 

The concept I like about Cn.F.4 = 1 is that it is `old style` if you like: my right thumb is just acting like my left hand does when I am manual focusing a lens; and my trigger finger is wired to timing the shot, and nothing else. That suits my brain and my shooting style, but I think, even if this procedure does not suit you long term, if you stick at it for a while it might identify and isolate what the problem is you are having.

 

 

WW