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I suppose it's only fitting...#@$%%# BACKFOCUS!!!

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That still doesn't mean that the focus area can't be larger than those rectangles as suggested. I really don't know either way, it is just that if this is true it would make your argument mute.

Rgds
KR
Victor Engel said:
Mark Gillett said:
Victor Engel said:
The tree edge is not in the focus region. The circle is NOT the
focus region. The red rectangles are.
Click to expand...
No they are not. The actual sensor size is about 80% bigger in the
form of a cross. This makes the tree in the focus zone. Do a
search and you will find the info somewhere. It has been discussed
to death on this forum. Perhpas ask DavidP or Mishkin and they
will point you to the material.
Click to expand...
Before you suggest that someone do the research on the topic you
suggest, you should first read the thread to which you're
responding to see if it has already been done!!!

Read up to my first comment in this thread. I post the picture
again here:



The red rectangles I was referring to are the red rectangles
appearing in this picture, which are the actual focus areas that
you alluded to, not the rectangles appearing in the viewfinder.
Click to expand...
 
Actually the focus point is fine. I don't have any issue with this photo.

If you look at the picture that you mentioned there are 3 vertial AF sensor that is active. One the front of the nose, one at between the eyes and at the back of the forehead. Note that these point are at different distance from the camera. The camera selected the AF point where is somewhere in between. If you like the nose to be sharp in focus may you should select the bottom AF point.


Michael Louis said:
pixydust said:
Michael Louis said:
when a lens backfocuses things look great in the viewfinder yet
when the mirror snaps back at the moment of truth the lens moves
it's focus point back and leaves the photographer scratching thier
head when reviewing what should have been in focus photos.
Click to expand...
What are you saying? Are you saying that when the focus is locked
the lens got moved after the mirror is open to take picture? You're
actually wittnessing this personally?
Michael Louis said:
Mark Gillett said:
DavidP said:
If there's not enough contrast, the AF shouldn't lock. It should
blink the green light, and refuse to fire a shot (in one-shot mode).
Click to expand...
This would happen if there was not enough contrast in the pic or
the sensor was the size of the red square. We all know that is not
the case so can we not accept what it has done. It looks fairly
obvious to me.
Michael Louis said:
Isn't the camera smart enough to recognize when there's not enough
contrast?
Click to expand...
As above!
Michael Louis said:
Apparently not. Even the 1D suffers from this . . . . apparently
not as frequently as the 10D, though.
Click to expand...
I know not.
Michael Louis said:
I agree that the tree stump would make a better AF target. But
it's plain stupid that the camera will mis-focus by such a large
amount and not know it. Of course, the extra-large AF sensor of
the 10D is largely to blame for this issue in this particular image.
Click to expand...
Take the actual sensor size into acount and it has not mis focussed.

What I find difficult is that the taker of the photo could not see
that it was locking on to the wrong subject just by looking into
the view finder.
Michael Louis said:
Jonathan Lefcourt said:
My 1D makes that shot for sure and probably my 10D get that shot
too. Maybe the lens is the problem. Try on diff. body to test the
lens.
Click to expand...
--
http://www.outboundmusic.com
Your link to independent music!
Click to expand...
--
http://www.pbase.com/markgillett
Click to expand...
Click to expand...
Click to expand...
Click to expand...
 
KR2 said:
That still doesn't mean that the focus area can't be larger than
those rectangles as suggested. I really don't know either way, it
is just that if this is true it would make your argument mute.
Click to expand...
Now you're backpeddling. I showed a picture using the zones you alluded to. Now you're suggesting they're wrong. Make up your mind. Then you'll at least be consistent.

Anyway, the picture of the red sensor areas originally came from Canon and allegedly correspond to the actual sensor areas. If this is the case, then the focus area can't be larger than those rectangles. Without further evidence to the contrary, I accept this version from Canon of where the sensor areas are.
 
Not really backpeddling. I still contend that the camera chose the dirt/sawdust just under (and barely in your rectangles) and behind the saw blade. Is there a problem with the lens or camera? I don't know. But, an argument can be made that the camera did focus on the more contrasty area in its focal range. If you are really trying to figure out a focus problem, I think all the posted examples are pretty poor for that purpose. I think the poster towards the bottom of the thread that suggested the boxes has the right idea.

Rgds
KR
Victor Engel said:
KR2 said:
That still doesn't mean that the focus area can't be larger than
those rectangles as suggested. I really don't know either way, it
is just that if this is true it would make your argument mute.
Click to expand...
Now you're backpeddling. I showed a picture using the zones you
alluded to. Now you're suggesting they're wrong. Make up your mind.
Then you'll at least be consistent.

Anyway, the picture of the red sensor areas originally came from
Canon and allegedly correspond to the actual sensor areas. If this
is the case, then the focus area can't be larger than those
rectangles. Without further evidence to the contrary, I accept this
version from Canon of where the sensor areas are.
Click to expand...
 
We can argue all day on whether the photos submitted demonstrate a focus problem. I think it's clear that they strongly SUGGEST a problem. A controlled test is what's called for.

By the way, yesterday I was shooting some test pictures of a paper target of a color grid in order to make profiles for neat image. I noticed that with the camera tripod mounted and pointed at the target, if I repeatedly half-pressed the shutter release (asking the camera to refocus) and observed the focus ring, I could see it barely adjusting itself sometimes. I know this has been discussed on this forum before. I think it clearly demonstrates a random component in the focusing system. I'm curious how many others here get similar results. Note that this test is only valid if the subject does not extend beyond the focal plane -- there is no ambiguity in what is really in focus.
 
KR2 said:
Not really backpeddling. I still contend that the camera chose the
dirt/sawdust just under (and barely in your rectangles) and behind
the saw blade.
Click to expand...
I concede that is a possibility. Some of the sawdust is just barely in the focus region.
KR2 said:
Is there a problem with the lens or camera? I
don't know. But, an argument can be made that the camera did focus
on the more contrasty area in its focal range. If you are really
trying to figure out a focus problem, I think all the posted
examples are pretty poor for that purpose. I think the poster
towards the bottom of the thread that suggested the boxes has the
right idea.
Click to expand...
Yes. There needs to be a controlled test where the focus area is unambiguous.
 
assumed this was the Mishkin Syndrome. Remember those experiments he posted the other day when red hued colors backfocused more than cyan and green?

I have taken other shots wide open with this lens in which this phenomenon didn't occur.

See the same folder I just added a few to confirm this. The third photo shows perfect focus using the 100 f/2 and the fourth shows the same Mishken phenomenon!! It's repeatable (Single focus point overthe right eye)! YET, the fifth photo shows that wide open the 50 1.8 mk I isn't susecptible to this phenomenon. So it must be the 100 f/2 lens, wide open, randomly is not capturing what I am seeing in the viewfinder with certain hues and it's not the camera itself. The second and sixth shot show the problem disappears at 2.8 on the 100 2.

I just wanted you and pixy to see I wasn't just 'making something up'; as you both doubted what I was saying.
DavidP said:
That would explain what you're experiencing.

Have you had that checked out yet?
Michael Louis said:
of what I am saying.
http://photos.yahoo.com/[email protected]
Look in the Miskin syndrome folder.
The first photo is the original from the 10D and 100 f/2. Download
and Look in the FUV and you'll see the focus points were the nose,
between the eyes and the forehead. Everything looked good in the
viewfinder so I snapped the shot.
Look at what the 10D did. It skipped over the nose, got the cheeks
and then somehow magically glossed over the eyes and front forehead
while getting the middle of the forehead.
God knows I was close enough to confirm that what I was seeing in
the viewfinder should be accurate, and you can see that the lens
chose something completly different.
How do you explain this phenomenon except that the moment the shot
was taken the lens chose only to focus on what it wanted regardless
of what I was seeing in the viewfinder.
Click to expand...
--
http://www.outboundmusic.com
Your link to independent music!
Click to expand...
 
because the camera gave me three focus points and in the viewfinder everything looked in focus confirming what the camera was seeing. Upon shooting the photo, the lens missed the nose altogether and glossed over the eyes selecting it's own plane of focus points on either side of the eyes and the mid forehead.

If it were just selecting a middle point then why light up all three? Why also are the cheeks in focus and the middle forehead. Those are two different focus points in this shallow dof photo.

To me it's clear that the lens upon capturing the photo chose to focus differently than what was shown to me in the viewfinder. I don't blame the 10D it perfectly lined up the three focus points for a perfect photo!
pixydust said:
If you look at the picture that you mentioned there are 3 vertial
AF sensor that is active. One the front of the nose, one at between
the eyes and at the back of the forehead. Note that these point are
at different distance from the camera. The camera selected the AF
point where is somewhere in between. If you like the nose to be
sharp in focus may you should select the bottom AF point.


Michael Louis said:
pixydust said:
Michael Louis said:
when a lens backfocuses things look great in the viewfinder yet
when the mirror snaps back at the moment of truth the lens moves
it's focus point back and leaves the photographer scratching thier
head when reviewing what should have been in focus photos.
Click to expand...
What are you saying? Are you saying that when the focus is locked
the lens got moved after the mirror is open to take picture? You're
actually wittnessing this personally?
pixydust said:
Mark Gillett said:
DavidP said:
If there's not enough contrast, the AF shouldn't lock. It should
blink the green light, and refuse to fire a shot (in one-shot mode).
Click to expand...
This would happen if there was not enough contrast in the pic or
the sensor was the size of the red square. We all know that is not
the case so can we not accept what it has done. It looks fairly
obvious to me.
pixydust said:
Isn't the camera smart enough to recognize when there's not enough
contrast?
Click to expand...
As above!
pixydust said:
Apparently not. Even the 1D suffers from this . . . . apparently
not as frequently as the 10D, though.
Click to expand...
I know not.
pixydust said:
I agree that the tree stump would make a better AF target. But
it's plain stupid that the camera will mis-focus by such a large
amount and not know it. Of course, the extra-large AF sensor of
the 10D is largely to blame for this issue in this particular image.
Click to expand...
Take the actual sensor size into acount and it has not mis focussed.

What I find difficult is that the taker of the photo could not see
that it was locking on to the wrong subject just by looking into
the view finder.
pixydust said:
Jonathan Lefcourt said:
My 1D makes that shot for sure and probably my 10D get that shot
too. Maybe the lens is the problem. Try on diff. body to test the
lens.
Click to expand...
--
http://www.outboundmusic.com
Your link to independent music!
Click to expand...
--
http://www.pbase.com/markgillett
Click to expand...
Click to expand...
Click to expand...
Click to expand...
Click to expand...
 
Perhaps I have better eyes than some (I seriously doubt it!) but that amount of mis-focus in the viewfinder would be IMMEDIATELY visible to me. If it weren't, I'd say the Canon 10D was a piece of junk as any SLR with a halfway decent viewfinder would show that amount of mis-focus unmistakably and immediately.

Learn to see, take your time.

Godfrey
DavidP said:
Yes, you should resort to some sort of chart/ruler test. Why?
It will tell you if it's a focus probleml that Canon can fix or
not. If you can't get it to fail in a test lilke Pekka's or
Mishkin's in good light, there's little Canon can do for you,
unfortunately.

If it does fail, then you know it's worth the time and hassle to
send it in .
Vern Stevens said:
When I looked through the viewfinder, it LOOKED in focus, just like
many of the in-focus shots I took with my 28-135 lens. If it
looked out of focus, I would have adjusted it. That's why Canon
includes viewfinders on their SLR's. And yes, my diopter is
properly set on the camera as well. I'm fully aware of full time
manual focusing, and would have tried that IF it appeared out of
focus through the viewfinder.

But, as I said, I will be trying more shots. Heck, I may even
resort to a ruler or a line chart at this point. :)
Click to expand...
--
http://www.outboundmusic.com
Your link to independent music!
Click to expand...
 
Michael Louis said:
because the camera gave me three focus points and in the viewfinder
everything looked in focus confirming what the camera was seeing.
Upon shooting the photo, the lens missed the nose altogether and
glossed over the eyes selecting it's own plane of focus points on
either side of the eyes and the mid forehead.
Click to expand...
Your eye doesn't have to deal DOF but the camera does. Given that you're shooting at f2 the camera know three things. The near, mid and far distance of the three 3D subject. It has to find out where to best place the focus plane so that the subject is in focus within the DOF.

In your opinion the camera should pick the nose to be sharpest and ignoring the rest of the subject. I'm not sure if any portrait photographer will be happy with that when their subject nose is in focus and the rest is a big blur. In shot like this where you want control where the focus point is an single AF focus point is more appropriate.

Another thing is what if another user like the ear to be in focus or may be the middle of the nose. How would the camera deal with these user.
Michael Louis said:
If it were just selecting a middle point then why light up all
three?
Click to expand...
It light up all three because it detected constrast and able to discern details. It's only and indicator of which AF points currently active and used for focusing.
Michael Louis said:
Why also are the cheeks in focus and the middle forehead.
Those are two different focus points in this shallow dof photo.
Click to expand...
True, but you can have only one focus plane. Things within the DOF should be in focus.
Michael Louis said:
To me it's clear that the lens upon capturing the photo chose to
focus differently than what was shown to me in the viewfinder.
Click to expand...
Actually the lens is dumb and has to be told by the camera in which direction it need to move the focus ring. Once the focus is locked the camera doesn't change the focus position unless you're using AI servos.
Michael Louis said:
I don't blame the 10D it perfectly lined up the three focus points
for a perfect photo!
Click to expand...
 
as in the clear examples I have shown in posts down on the thread tree here. Also, the same thing was happening to my 70-200 4L yet much worse and in all aperatures. Upon capturing the lens chose a different focus point than what is confirmed by the focus points and seen in the viewfinder.

I sent mine back to Canon, as I mentioned to DavidP ealier, and they did an excellent job of calibrating. Now, WISIWIG!

Tell them to take thier time and recalibrate, which is what I did; and now I am what's called 'a happy camper'.
Godfrey said:
Learn to see, take your time.

Godfrey
DavidP said:
Yes, you should resort to some sort of chart/ruler test. Why?
It will tell you if it's a focus probleml that Canon can fix or
not. If you can't get it to fail in a test lilke Pekka's or
Mishkin's in good light, there's little Canon can do for you,
unfortunately.

If it does fail, then you know it's worth the time and hassle to
send it in .
Vern Stevens said:
When I looked through the viewfinder, it LOOKED in focus, just like
many of the in-focus shots I took with my 28-135 lens. If it
looked out of focus, I would have adjusted it. That's why Canon
includes viewfinders on their SLR's. And yes, my diopter is
properly set on the camera as well. I'm fully aware of full time
manual focusing, and would have tried that IF it appeared out of
focus through the viewfinder.

But, as I said, I will be trying more shots. Heck, I may even
resort to a ruler or a line chart at this point. :)
Click to expand...
--
http://www.outboundmusic.com
Your link to independent music!
Click to expand...
Click to expand...
 
With an angle finder C and F1.4 on my 50mm, I can clearly see through the angle finder the exact plane of intended focus through the viewfinder, yet after releasing the shutter, the image is oof.

The only reason I can see is that the light path distance from the lens to the mirror/viewfinder is different than from the lens to the sensor.

I don't think that this is caused by a misaligned sensor as it would affect both paths, however, it could be due to the focus screen needing adjustment.

And you will notice that in the repair/parts manual that David posted the other day, there is a part that can be ordered to make precisely this adjustment. The part is available in about 8 different thicknesses and is used to adjust the elevation of the focusing screen. There is also another shim to adjust the lens mount, but this would not cause the behaviour I have described, as again, the light path distance would change equally for both.

mark.
Michael Louis said:
DavidP said:
I'd be curious to see how you're arriving at that particular
conclusion. Would seem to be hard to demonstrate.
Michael Louis said:
when a lens backfocuses things look great in the viewfinder yet
when the mirror snaps back at the moment of truth the lens moves
it's focus point back and leaves the photographer scratching thier
head when reviewing what should have been in focus photos.
Click to expand...
--
http://www.outboundmusic.com
Your link to independent music!
Click to expand...
Click to expand...
 
Vern,

Your choice of subjects and how you shot them is fraught with chances for focusing errors - human and camera. Let's look at each one.
Vern Stevens said:
Vern Stevens said:
All of these pics were center focus point selected and focused off
Click to expand...
of without reframing with one exception which I will explain later.

Click to expand...
This is a notoriously difficult image to get autofocus to work correectly on. You just have too many chances for the camera to choose the wrong object. Watever it chose, it is clearly NOT backfocusing!!!
Vern Stevens said:
Full Image: http://www.pbase.com/image/23667311/original

Focused on the center, but the further part of the cage to the left
is in focus. No more contrast there than there was were the focus
point was.

Two pics of a rock: The first was taken focused at 70mm then
zoomed in to 200mm to take picture. The second was focused and
taken at 200mm.
Click to expand...
Were you possibly too close here? There is a minimum focusing distance for every lens and you hve to be aware of what it is. Additionally, the 70-200 has a focus distance limiting switch which can prevent it from focusing closer than the switch allows (I forget ehat the disance is now, but it's printed by the switch). If the switch is in the wrong position it can limit the close focusing even further. Plus as DavidP points out (and the manual points out) you should zoom first and focus after!
Vern Stevens said:


Full Image Rock 1: http://www.pbase.com/image/23667313



Full Image Rock 2: http://www.pbase.com/image/23667316/original

Notice on the second rock that the center, which has just as much
contrast as the top part (or farthest part) is blurry and the top
is sharp.

Lastly, the squirrel.
Click to expand...
Again, like the first pic, to many chances for the camera to focus on the wrong thing - a branch or whatever. This is what FTM focusing is for - just these situations.
Vern Stevens said:


Full Image: http://www.pbase.com/image/23667318/original

The squirrel is slightly blurry, which takes up alot of the sensor,
and the small branch behind the squirrel is sharper, hardly hitting
the sensor.

So, am I crazy, or is this backfocusing?
Click to expand...
Once again, your camera still MIGHT be backfucusing - I'm not saying it isn't. I just don't see any of thse pictures as proof that it is. Put a chair out on an open lawn and focus on that. That will remove most of the variables you have here. It's big enough that you can get far enough away from it and still get the WHOLE AF point on it, and there will be nothing else to confuse the AF.

AF is not magic. It can and will be fooled in tough situations. Try to find a better test case and post that.

= Ed =
--
= Ed Rotberg =

'A waist is a terrible thing to mind'
http://www.edrotberg.org/gallery
 
How much does Canon charge for this service?
Michael Louis said:
as in the clear examples I have shown in posts down on the thread
tree here. Also, the same thing was happening to my 70-200 4L yet
much worse and in all aperatures. Upon capturing the lens chose a
different focus point than what is confirmed by the focus points
and seen in the viewfinder.
I sent mine back to Canon, as I mentioned to DavidP ealier, and
they did an excellent job of calibrating. Now, WISIWIG!
Tell them to take thier time and recalibrate, which is what I did;
and now I am what's called 'a happy camper'.
Click to expand...
 
pixydust said:
Michael Louis said:
because the camera gave me three focus points and in the viewfinder
everything looked in focus confirming what the camera was seeing.
Upon shooting the photo, the lens missed the nose altogether and
glossed over the eyes selecting it's own plane of focus points on
either side of the eyes and the mid forehead.
Click to expand...
Your eye doesn't have to deal DOF but the camera does.
Click to expand...
Actually though my eye doesn't have to deal with the DOF at that shallow range, my mind can; and given what the 10D revealed to me by lighting up the three focus points my mind knew the focal length and the distance so I had a rough idea of what to expect.

Given that you're shooting at f2 the camera know three things. The near, mid and far distance of the three 3D subject. It has to find out where to best place the focus plane so that the subject is in focus within the DOF.

This doesn't explain how it focused on the left AND right cheek; glossed over the eyes and picked up on the rear of the forehead.
pixydust said:
In your opinion the camera should pick the nose to be sharpest and
ignoring the rest of the subject.I'm not sure if any portrait
photographer will be happy with that when their subject nose is in
focus and the rest is a big blur.
Click to expand...
If just the nose were lit up I wouldn't have snapped the shot. No offence taken.
pixydust said:
In shot like this where you want control where the focus point is an single AF focus point is more appropriate.
Click to expand...
Not true, the camera showed me very useful focus points confirmed in the viewfinder. It hit one of them dead on (the forehead), missed the nose altogether and on the middle point it magically got the cheeks and missed the eyes which were in the EXACT focal plane of the cheeks directly under the eyes. How do you explain this? I don't think you can.
pixydust said:
Another thing is what if another user like the ear to be in focus
or may be the middle of the nose. How would the camera deal with
these user.
Click to expand...
N/A
pixydust said:
pixydust said:
If it were just selecting a middle point then why light up all
three?
Click to expand...
It light up all three because it detected constrast and able to
discern details. It's only and indicator of which AF points
currently active and used for focusing.
Click to expand...
So which is it; three focus points or one single focus point:

" The camera selected the AF point where is somewhere in between" as you put it. If that is indeed the case we go back to why it missed the eyes which was 'in between' and hit the mid forehead?
pixydust said:
pixydust said:
Why also are the cheeks in focus and the middle forehead.
Those are two different focus points in this shallow dof photo.
Click to expand...
True, but you can have only one focus plane. Things within the DOF
should be in focus.
Click to expand...
Are we seeing the same thing and are just going in circles? What that photo revealed was one focal plane with certain parts within that plane out of focus...ie the eyes. Forget the nose for a second and just explain the eyes!
pixydust said:
pixydust said:
To me it's clear that the lens upon capturing the photo chose to
focus differently than what was shown to me in the viewfinder.
Click to expand...
Actually the lens is dumb and has to be told by the camera in which
direction it need to move the focus ring. Once the focus is locked
the camera doesn't change the focus position unless you're using AI
servos.
Click to expand...
The lens is not dumb at all and contains all kind of electronic data in which it comunicates with the camera.
pixydust said:
pixydust said:
I don't blame the 10D it perfectly lined up the three focus points
for a perfect photo!
Click to expand...
Click to expand...
 
In that image, there is no way in HECK that all three points can be in focus at the given aperture.

So, the 10D should NOT indicate that all of these points are in focus. It should tell you which one is in focus.

Period.

Michael Louis wrote:



--
http://www.outboundmusic.com
Your link to independent music!
 
what these photos reveal is that when the 10D is jiving properly with a decent lens wide open the photos don't 'need' post processing to make them sharp as is touted often in these forums.
DavidP said:
And not positive about the explanation, either.
Michael Louis said:
I just wanted you and pixy to see I wasn't just 'making something
up'; as you both doubted what I was saying.
Click to expand...
--
http://www.outboundmusic.com
Your link to independent music!
Click to expand...
 
end the story right there. I agree that the three points was silly in so shallow a DOF; yet there has to be a sane and reasonable explanation as to why it hit the cheeks to the side of , under and in front of the eyes while missed the eyes altogether. The lens then had the audacity to then pick up on the top of the forehead.
Where the heck is Mishkin when you need him!! LOL
DavidP said:
In that image, there is no way in HECK that all three points can be
in focus at the given aperture.

So, the 10D should NOT indicate that all of these points are in
focus. It should tell you which one is in focus.

Period.

Michael Louis wrote:



--
http://www.outboundmusic.com
Your link to independent music!
Click to expand...
 
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