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10D Back Focus
- Thread starter Dan156743
- Start date
Wel, the difference between us that I participate in other threads as well but you restrict yourself to the "10D issues" threads exclusively.
No, I rarely ever see you mention good things about the 10D.
Like I said before, you seem to restrict yourself to the "10D issues" threads and you're usually bolstering the negative side or condemning the people who speak well of the 10D.
It IS possible that the AF was fooled by a spot of the rug within the AF sensor area which is larger than the small square indicates. All I'm saying is why didn't give the AF a DEFINITE target to lock onto rather than an obscure one? It seems like he wanted the AF to fail rather than give it the best opportunity to succeed.
Peter Phan
Senior Member
Are you positive about the 2 meter shooting distance? It would seem that shooting at 2 meters at f/4 would yield more depth of field than a mere inch or so. Even shooting from 2 meters at 200mm at f/4 would yield at least an inch of depth of field. The depth of field you are showing is much less than that. What focal length were you shooting at? The 1.2 meter minimum focus distance may not pertain to the focal length you were using!
FrancisCF
Leading Member
I'm sorry that it's my fault to make you think like that.
Actually I've no bias in camera brand, since my gears are from various brand. I pay so much attention to 10D because I really want one, being waited since D100, then S2pro and until the 10D which I think I ought to make the plunge, but.... For the CS and NS here, that is my true experience in previous days, and still there are some 10D owners struggling from getting theirs from CS.
Go ahead, never look back
Actually I've no bias in camera brand, since my gears are from various brand. I pay so much attention to 10D because I really want one, being waited since D100, then S2pro and until the 10D which I think I ought to make the plunge, but.... For the CS and NS here, that is my true experience in previous days, and still there are some 10D owners struggling from getting theirs from CS.
--
Go ahead, never look back
Go here and look at the focus test using a sheet with gridlines. The center focus point was not fooled on this test as you suggest and it produced the same results.
You seem to beg to differ with the obvious. I wonder if perhaps you are a Canon employee?
http://forums.dpreview.com/forums/read.asp?forum=1019&message=5129295
You seem to beg to differ with the obvious. I wonder if perhaps you are a Canon employee?
http://forums.dpreview.com/forums/read.asp?forum=1019&message=5129295
Hi Peter Pan -
I am begining to think you are a rocket scientist or a Canon employee. For your edification I measured the gridlines on the sheet I used. The depth of field is one inch. You keep referencing 200mm. Keep in mind due to the size of the CMOS there is a ratio of 1.6 to one that needs to be considered so the effective focal length is 320 mm.
Keep in mind Peter you stated one inch of depth of field and that is what I got.
Instead of seeing the obvious and recognizing that Canon is producing defective cameras and providing ineffective repair service leads me to believe you are a Canon employee.
I am begining to think you are a rocket scientist or a Canon employee. For your edification I measured the gridlines on the sheet I used. The depth of field is one inch. You keep referencing 200mm. Keep in mind due to the size of the CMOS there is a ratio of 1.6 to one that needs to be considered so the effective focal length is 320 mm.
Keep in mind Peter you stated one inch of depth of field and that is what I got.
Instead of seeing the obvious and recognizing that Canon is producing defective cameras and providing ineffective repair service leads me to believe you are a Canon employee.
I already saw that test and you STILL won't show any of your "real world" shots as I've asked for at least a couple of times. Also, you entered this whole thing with an antagonistic attitude like you dared anyone to find fault with anything you did. You seem to refuse any suggestion that opposes your foregone conclusion. As for my status at Canon, you're about the 5th person to accuse me of that. I guess it's just standard procedure to try to the discredit angle.
I dared to find fault. It almost sounds like your purpose is to find fault. That is why I believe you work for Canon. What I find interesting is that in your last reply you did not deny working for Canon!
I will post an example per your request. It may be later tonight or tomorrow. Stay tuned. I will leave the EXIF data intact and post the original image unretouched.
As far as a foregone conclusion is concerned you fail to recognize I did three controlled focus tests all of which showed back focus. The conclusion is foregone per the tests.
Why do you keep trying to find fault?
I will post an example per your request. It may be later tonight or tomorrow. Stay tuned. I will leave the EXIF data intact and post the original image unretouched.
As far as a foregone conclusion is concerned you fail to recognize I did three controlled focus tests all of which showed back focus. The conclusion is foregone per the tests.
Why do you keep trying to find fault?
No, I am someone who bought a 10D with expectations only to learn the camera is defective. I sent it for repairs once and it came back defective. What is up with Canon! Why are so many people having problems with focus?
As far as the camera goes it is remarkable. If you look at the focus test you can see the fibers in the paper. I shot upwards of 800 images and the exposures were right on the mark, resolution outstanding, etc. Hell, the pictures had a wondeful filmlike quality. All that Canon has put into the 10D does not matter though if it won't focus accurately and/or if they can't fix it correctly. I am not happy about buying a camera body I can't use. I am not happy about spending a small fortune on shipping and insurance back and forth to Canon. I am not happy about the downtime. Most importantly, I am not happy about Canon keeping quiet on the issue and voiding the obvious.
I am a consumer and I don't like being screwed out of my money.
Yes, I am unhappy about all of this.
As far as the camera goes it is remarkable. If you look at the focus test you can see the fibers in the paper. I shot upwards of 800 images and the exposures were right on the mark, resolution outstanding, etc. Hell, the pictures had a wondeful filmlike quality. All that Canon has put into the 10D does not matter though if it won't focus accurately and/or if they can't fix it correctly. I am not happy about buying a camera body I can't use. I am not happy about spending a small fortune on shipping and insurance back and forth to Canon. I am not happy about the downtime. Most importantly, I am not happy about Canon keeping quiet on the issue and voiding the obvious.
I am a consumer and I don't like being screwed out of my money.
Yes, I am unhappy about all of this.
Dan wrote:
"... The depth of field is one inch. You keep referencing
That 1.6-1 ratio that you refer to, is a crop factor, not a focal length muliplier.
The image focuses through the lens, and on the sensor in the exactly same size, and with the exact same DOF, as it would if that lens was mounted to a 35mm camera, or a digital with a full size sensor.
There is great deal of confusion being caused with the focal length of lenses mounted to the 10D camera.
Most of this confusion is caused by well intentioned people telling folks to multiply the lenses focal length by 1.6 to get that lenses, "effective focal length".
The focal length of the lens doesn't change, the sensor beinging 38% smaller than a 35mm frame, the sensor only captures the center portion of what would be a 35mm image.
When this smaller image is viewed, it appears to have been shot with a longer lens.
"... The depth of field is one inch. You keep referencing
Dan, that not really true.
That 1.6-1 ratio that you refer to, is a crop factor, not a focal length muliplier.
The image focuses through the lens, and on the sensor in the exactly same size, and with the exact same DOF, as it would if that lens was mounted to a 35mm camera, or a digital with a full size sensor.
There is great deal of confusion being caused with the focal length of lenses mounted to the 10D camera.
Most of this confusion is caused by well intentioned people telling folks to multiply the lenses focal length by 1.6 to get that lenses, "effective focal length".
The focal length of the lens doesn't change, the sensor beinging 38% smaller than a 35mm frame, the sensor only captures the center portion of what would be a 35mm image.
When this smaller image is viewed, it appears to have been shot with a longer lens.
After reading several threads regarding this issue...I couldn't resist....The first thing I did was test the autofocus at macro distances on my 28-135 IS and cheap 28-200.
Conclusion? Perfect AF in almost all cases. I did my best to fool the system by selecting a couple of low contrast subjects, etc...most of the time AF was still right on.
This is my first SLR (let alone DSLR) so I am undeniably an amateur here. I am just starting to get my mind around DOF, etc (thanks to many of the posters here). Bottom line? If its a piece of cake for ME, then the camera must be working....#:>
Don't take my word for it....several of the pictures posted in the canon SLR forum speak for themselves.
Anyway Dan...I'm sorry if your camera doesn't seem to work for you. I am extrememly satisfied with mine. And I sincerely hope that anyone reading these AF threads and thinking about buying a 10D take in to consideration that there are more than a few of us here who's 10Ds worked just fine...right out of the box!
Conclusion? Perfect AF in almost all cases. I did my best to fool the system by selecting a couple of low contrast subjects, etc...most of the time AF was still right on.
This is my first SLR (let alone DSLR) so I am undeniably an amateur here. I am just starting to get my mind around DOF, etc (thanks to many of the posters here). Bottom line? If its a piece of cake for ME, then the camera must be working....#:>
Don't take my word for it....several of the pictures posted in the canon SLR forum speak for themselves.
Anyway Dan...I'm sorry if your camera doesn't seem to work for you. I am extrememly satisfied with mine. And I sincerely hope that anyone reading these AF threads and thinking about buying a 10D take in to consideration that there are more than a few of us here who's 10Ds worked just fine...right out of the box!
Thank you for the clarification, which makes sense and stands to reason.
Peter Phan
Senior Member
Try the test discussed here:
http://forums.dpreview.com/forums/read.asp?forum=1019&message=5081290
I personally don't see any problem with the results of your focus test. To me, it certainly seems to be within tolerance of a zoom lens at very close focus distance. But I do think you might put your mind at ease with the test linked above. It' a much more controlled test. Who knows, maybe with your rug test, the autofocus was indeed fine but it got fooled just a tad. I think that if you had focused on the pen instead of the rug, you might not have had an issue. That's just good autofocus technique. Autofocus systems aren't very smart. They're good, but not fool-proof. Do the focus test above, preferably at adequate focus distance or with a macro lens for shorter focus distance.
http://forums.dpreview.com/forums/read.asp?forum=1019&message=5081290
I personally don't see any problem with the results of your focus test. To me, it certainly seems to be within tolerance of a zoom lens at very close focus distance. But I do think you might put your mind at ease with the test linked above. It' a much more controlled test. Who knows, maybe with your rug test, the autofocus was indeed fine but it got fooled just a tad. I think that if you had focused on the pen instead of the rug, you might not have had an issue. That's just good autofocus technique. Autofocus systems aren't very smart. They're good, but not fool-proof. Do the focus test above, preferably at adequate focus distance or with a macro lens for shorter focus distance.
repeat the tests with different framing..
1) have the close subject on top half of the frame instead of the bottom
2) tilt your test pattern or camera 90 degrees and try again.
3) from 1), tilt your test pattern or camera 90 degrees the other way
if in all instance it focuses too far back, then it probably is a back focus problem, else it could be the AF sensor is not aligned in the center of the frame.
4) try AF focusing from both front and back.
1) have the close subject on top half of the frame instead of the bottom
2) tilt your test pattern or camera 90 degrees and try again.
3) from 1), tilt your test pattern or camera 90 degrees the other way
if in all instance it focuses too far back, then it probably is a back focus problem, else it could be the AF sensor is not aligned in the center of the frame.
4) try AF focusing from both front and back.
lightcatcher
Member
I also seem to have similar back-focuse problem with my 10D. However for me I can acutally see in the view finder that the image is not quite focused/sharp after the camera finishes auto focusing (i.e. the focus confirmation led is lit). But I remember reading the posts of people who reported focusing problem saying that things look sharp in the view finder but not so on when view the actual image. Anyway, here are some my test shots using the (now ubiquitous) focus test chart.
chart position in a 45 degree incline (cropped to reduce size)
http://www.pbase.com/image/16831161/original
chart positioned straight up (parrell to the lens), shot with auto focus.
http://www.pbase.com/image/16831498/original
chart positioned straight up (parrell to the lens), manually adjusted focus ring after camera auto-focused
http://www.pbase.com/image/16831498/original
The lens used is 70-200F4, camera mounted on tripod, 2m from subject. I contacted onecall.com for an exchange, however the person that I talked to said that if Canon does't acknowledge that there's a defect, I'll have to pay a 15% restocking fee. So if anyone who doesn't think that the focus issues are real, I can give you the $220 (15%*$1499) if you are willing to exchange your good 10D with mine 
Edgar
chart position in a 45 degree incline (cropped to reduce size)
http://www.pbase.com/image/16831161/original
chart positioned straight up (parrell to the lens), shot with auto focus.
http://www.pbase.com/image/16831498/original
chart positioned straight up (parrell to the lens), manually adjusted focus ring after camera auto-focused
http://www.pbase.com/image/16831498/original
The lens used is 70-200F4, camera mounted on tripod,
Edgar
lightcatcher
Member
I posted the wrong link for the manual focused image. Here's the correct link:
http://www.pbase.com/image/16831163
Edgar
http://www.pbase.com/image/16831163
Edgar
I also seem to have similar back-focuse problem with my 10D.
However for me I can acutally see in the view finder that the image
is not quite focused/sharp after the camera finishes auto focusing
(i.e. the focus confirmation led is lit). But I remember reading
the posts of people who reported focusing problem saying that
things look sharp in the view finder but not so on when view the
actual image. Anyway, here are some my test shots using the (now
ubiquitous) focus test chart.
chart position in a 45 degree incline (cropped to reduce size)
http://www.pbase.com/image/16831161/original
chart positioned straight up (parrell to the lens), shot with auto
focus.
http://www.pbase.com/image/16831498/original
chart positioned straight up (parrell to the lens), manually
adjusted focus ring after camera auto-focused
http://www.pbase.com/image/16831498/original
The lens used is 70-200F4, camera mounted on tripod,2m from
subject. I contacted onecall.com for an exchange, however the
person that I talked to said that if Canon does't acknowledge that
there's a defect, I'll have to pay a 15% restocking fee. So if
anyone who doesn't think that the focus issues are real, I can give
you the $220 (15%*$1499) if you are willing to exchange your good
10D with mine
Edgar
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