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Thread started 04 May 2003 (Sunday) 07:58
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10D focus issue demystified

 
Pekka
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May 04, 2003 07:58 |  #1

Hi,

As I see posts with varying degrees of knowledge, guesswork and plain wrong facts about this matter (not to mention very different approaches to discuss and analyze this matter) I'd like you to read and understand some FACTS about 10D focus issue. I have many of these from Canon, and based on my own 10D experience.

(ADDENDUM 9.7.2003)
FACT: "The vertical component of the center focusing point for the 10D is equal in coverage to that of the D30 and D60, whereas the horizontal component is approximately 20% longer. In all cases, the actual area that can potentially be evaluated by the AF system is larger than indicated by the AF frame engraved on the focusing screen." From http://robgalbraith.co​m ...&Number=148832#Post​149286 (external link)

**Previous Test chart no longer available. Here is a good one as of August 2009;
http://www.hkdotnet.co​m ...st/AF_test_chart-a4-w.bmp (external link)

and

"The verbal way of describing the length of the 10D's 5 vertical AF sensor arrays is that they are approximately 2.25 times longer than the vertical dimension of the frames that are engraved on the focusing screen. The 3 horizontal arrays are the same length as the 5 vertical arrays. All sensor arrays are slightly narrower than the area indicated by the engraved frames."
from http://www.robgalbrait​h.com ...&Board=UBB8&Number=​149393 (external link)

Both texts and AF array image by Mr. Chuck Westfall (Director/Technical Information Dept.)
(ADDENDUM 9.7.2003)

FACT:
10D camera body has no focus issue.

FACT:
Some 10D's camera bodys have problems in focusing or getting sharp photos.

FACT:
To make sure there is no user error in question this problem must be verified with testing, and the test should be done (according to Canon Japan):

- from 2.5m
- with a 50mm lens
- in at least 12EV light (ISO 100, 5.6 1/125 equiv.)
- on sturdy tripod (mirror lock and external/timed release)
- "One shot" focus mode
- manual focus point (center).
- Largest aperture of the lens. This means use smallest f-number you can get.

The testing target can be built from a paper with some scale, and a cardboard focus point with white rectangle of black background. Canon test setup is something like this:

IMAGE NOT FOUND IMAGE IS A REDIRECT OR MISSING!
http://photography-on-the.net/10D/test.gif (external link)
HTTP response: NOT FOUND | MIME changed to 'text/html'


(The drawing is not in scale, sorry). The focus rectangle should be tack sharp and on the scale you can see how depth-of-field distributes. If rectangle is out of focus the scale tells you how much it is out and into what direction.

Image of this test (from Canon's Finnish repair center), with 200mm lens:

IMAGE NOT FOUND IMAGE IS A REDIRECT OR MISSING!
http://photography-on-the.net/10D/focus.jpg (external link)
HTTP response: NOT FOUND | MIME changed to 'text/html'


Other usable test is at http://www.hkdotcom.ne​t ...channel/AF_Test/ind​ex.htm (external link) - you can use that chart in above Canon type testing, but you don't want to focus to the chart itself as told on that page. It is important that what you focus to is a flat plane facing to the camera - any 3D information there makes test results unreliable.

Make sure that viewfinder focus rectangle sees only one possible focus point. Always use One Shot focus mode with center point only for testing. Alighn the test so that the plane of focus is not slanted - if you think you can't do the test ask someone more experienced to do it for you.

FACT:
Do not to fully trust you own tests - they just indicate something. If you get repeatedly off focus results, take the camera to repair and let them test it again there and make their own concusions. In the end Canon is the only authority that can confirm any focus errors in your camera body.

FACT:
Of those problematic 10D's some can be fixed by calibrating, some must be replaced.

FACT:
No one knows how many cameras has this problem. Perhaps only few. Perhaps more. Fact is that no one knows.

FACT:
This problem is not related to body serial numbers.

FACT:
There is no "body thickness issue" - it was a false alarm, it was tracked to be an error in Canon 10D repair manual.

FACT:
There is really no reason to know in technical terms what causes this problem. Canon repair fixes or replaces those bodies, that should be enough.

FACT:
Canon has been really polite and helpful on getting those bad seeds replaced or fixed. So please don't overreact and pour you anger onto them, even if Canon Japan has not made no official comments on this problem.

FACT:
Focus error can be "front" focus or "back" focus. Front means camera focuses closer to you, back means the camera focuses further away from intended focus point.

FACT:
Slight focus shifting (repeated tries give slightly different focus lock) is normal to autofocus systems. Focus shifting may be increased by dust and dirt inside camera body parts, dust or dirt on lens back, dust or dirt on filters/lens.

FACT:
Focusing can get out of calibration if you drop your camera or handle it rough.

FACT:
Resetting camera does not fix focusing.

FACT:
10D is the "most recommended" digital SLR I know, I really really like it.

FACT:
I may have forgotten some facts.

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lziering
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May 04, 2003 08:45 |  #2

Bob Atkins, of Photo.net fame, has posted an interesting 10D focus test and test target for nervous 10D owners.




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Pekka
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May 04, 2003 08:51 |  #3

lziering wrote:
Bob Atkins, of Photo.net fame, has posted an interesting 10D focus test and test target for nervous 10D owners.

http://www.photo.net/l​earn/focustest/external link

It is about the same as described in http://www.hkdotcom.ne​t ...channel/AF_Test/ind​ex.htmexternal link


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lziering
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May 04, 2003 09:33 |  #4

Pekka wrote:
lziering wrote:
Bob Atkins, of Photo.net fame, has posted an interesting 10D focus test and test target for nervous 10D owners.

http://www.photo.net/l​earn/focustest/external link

It is about the same as described in http://www.hkdotcom.ne​t ...channel/AF_Test/ind​ex.htmexternal link

I just tested my 10D the test using a Canon 50mm f/1.4 wide open. It failed!!!


I took delivery of my camera the first week they shipped in the US, March 15, 2002. (SN 0220105430). Boy, am I surprised!

I've repeated the test using different target types and I get similar results. I was also surprised to find that I get the same results when I repeat the test using manual focus and ignore the assist light in the viewfinder.. Anybody care to explain?

I'd show the test but posting on this site never seems to work for me.




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AndyDe
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Essex, UK
May 04, 2003 16:53 |  #5

Just tried the test on my 10D with 50mm 1.8 at f1.8 & the dof extends 1cm either side of the focus point so all seems ok. ( Body sn. 02301xxxxx)




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Longwatcher
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May 05, 2003 09:11 |  #6

Well I had to go and try it for myself.
Shot an angled ruler with all five of my lenses.

The 10D was spot on with all but my 75-300 IS, which very slightly front focused, by about 0.25cm at 2 meters (consistently over 3 shots each at 75 and 300).

On the other hand, I had to go and try my D60 as well.

Darn thing back focuses about an 1cm at 2 meters range with my 50/1.4 and 28-135 (I saw enough with just these two lenses.

In other trivia: in order of sharpness -
- 50/1.4L
- 100-400L IS (IS off)
- 75-300 IS (very slightly better without IS then with).
- 16-35L
- 28-135 IS

Lastly, having satisfied my curiosity - I LOVE MY 10D.
Of course I like my D60 also. Close enough for me.


"Save the model, Save the camera, The Photographer can be repaired"
www.longwatcher.comexternal link
1DsMkIII as primary camera with f2.8L zooms and the 85L
http://www.longwatcher​.com/photoequipment.ht​mexternal link

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emamb
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May 05, 2003 10:41 |  #7

Hi
Have done the tests with a canon 50mm lens and the results and other photos are great. What i still cannot understand though, is why i still cannot get sharp focusing with a 23-108mm mk 11 lens which works perfect with an eos 3. I don't want to use a 50mm prime all the time.
emamb




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dcchan2
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May 05, 2003 13:54 |  #8

Pekka wrote:
I may have forgotten some facts.

One question I have is:

Assuming the camera body needs to be calibrated, is it necessary to calibrate it using each of the lenses I have in my possession?




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lziering
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May 05, 2003 16:29 |  #9

longwatcher wrote:
Well I had to go and try it for myself.
Shot an angled ruler with all five of my lenses.

The 10D was spot on with all but my 75-300 IS, which very slightly front focused, by about 0.25cm at 2 meters (consistently over 3 shots each at 75 and 300).

On the other hand, I had to go and try my D60 as well.

Darn thing back focuses about an 1cm at 2 meters range with my 50/1.4 and 28-135 (I saw enough with just these two lenses.

In other trivia: in order of sharpness -
- 50/1.4L
- 100-400L IS (IS off)
- 75-300 IS (very slightly better without IS then with).
- 16-35L
- 28-135 IS

Lastly, having satisfied my curiosity - I LOVE MY 10D.
Of course I like my D60 also. Close enough for me.

Just a small point, but I don't think Canon makes a 50mm f/1.4 "L" lens. Either its a f/1.2 or its not an "L".




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Roger_Cavanagh
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May 05, 2003 16:35 |  #10

dcchan2 wrote:
Pekka wrote:
I may have forgotten some facts.

One question I have is:

Assuming the camera body needs to be calibrated, is it necessary to calibrate it using each of the lenses I have in my possession?

The Chasseur d'Images that disclosed that Canon France has reocgnised this as a problem said that, if you get a problem with all lenses then the recommendation was only send the camera.

OTOH, if you send the camera and one or more lenses and have another camera, the question is "will the lens adjustment impact the other camera?".

The Canon Germany test (described here http://www.pixelpixel.​org/helpinfo/23_focusc​heck.htmexternal link) does not require as much effort as FF/BF testing. It just determines whether you can manually focus more accurately than AF. I'f run all your lenses though this and decide whether you should send them with the camera. Of course, they have to be Canon lenses.

Regards,


=============
Roger Cavanagh
www.rogercavanagh.comexternal link

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tony723
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Joined Dec 2001
May 06, 2003 00:47 |  #11

Pekka wrote:
Hi,

As I see posts with varying degrees of knowledge, guesswork and plain wrong facts about this matter (not to mention very different approaches to discuss and analyze this matter) I'd like you to read and understand some FACTS about 10D focus issue. I have many of these from Canon, and based on my own 10D experience.

FACT:
No one knows how many cameras has this problem. Perhaps only few. Perhaps more. Fact is that no one knows.

Hi Pekka,

So it is a quality control issue. In fact this time Canon may have a lesson learnt that even a few faulty cameras (no one knows) may create lots of troubles and concerns from the customers around the world. The same issue did not happen for D30 and D60.


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AndyDe
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Essex, UK
May 06, 2003 01:58 |  #12

What I don't understand is that if the subject is in focus when viewed on the focucing screen in the viewfinder yet is 1cm back focused on the sensor this would imply a 1cm difference in the lens to screen & lens o sensor distance....surely this is impossible bearing in mind the physical size of the camera.




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Longwatcher
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May 06, 2003 08:19 |  #13

lziering wrote:

Just a small point, but I don't think Canon makes a 50mm f/1.4 "L" lens. Either its a f/1.2 or its not an "L".

Oops!

Got carried away. Image quality wise, I keep thinking of it as a "L" series, but you are correct.


"Save the model, Save the camera, The Photographer can be repaired"
www.longwatcher.comexternal link
1DsMkIII as primary camera with f2.8L zooms and the 85L
http://www.longwatcher​.com/photoequipment.ht​mexternal link

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fredlord
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Joined Jan 2003
May 06, 2003 10:08 |  #14

I had problems manually focusing when wearing my glasses rather than contact lenses. This directed my attention to the diopter adjustment on the eyepiece. I found, through experimentation, that I needed to set the diopter to something other than “0†for both eyeglasses and contacts. This had a definite influence on proper focus when I was doing it manually. If the diopter adjustment was not properly set for me I could not accurately focus manually. The diopter setting definitely changes the focus point for me. Now that it's set, I've had much better luck using the 100-400mm L IS lens with the 1.4x II TC which does not autofocus on my D60.

It may be obvious to all of you but the point is that if you are comparing the autofocus with your manual focusing, you should make sure you are manually focusing correctly.




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martcol
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May 06, 2003 14:45 |  #15

fredlord wrote:
make sure you are manually focusing correctly.

I got really paranoid about my 10D and autofocus! I did a test over weekend taking pictures on a tripod, of a text on white page of paper with a strong pattern and a line drawn in centre. Manual focus then auto from different angles with lens wide open - Canon 50mm 1.8. I took it in turns with my 14 yr old daughter to manual focus (younger eyes, much younger!) 8)

If anything gave inconsistent results it was my manual focussing! I think I need callobrating! :D

Martin


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