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

[David Mielcar]

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).

Apparently there WAS enough contrast, that's why it locked. How the hell was the camera to know the photographer was aiming for the blade not for the objects behind it ???

Isn't the camera smart enough to recognize when there's not enough
contrast?

it is, look above and look at other posts here - more people stressed that this particular situation was most likely very confusing for the system...

Apparently not. Even the 1D suffers from this . . . . apparently
not as frequently as the 10D, though.

Apparently yes ! We all appreciate the improvement of 10D's ability to focus in low light situations, don't we ? So again - it did just what it was designed to do. It found a contrasty ENOUGH object to lock the focus on and so it did ! The only thing you seem to call STUPID is that the camera doesn't KNOW which of those low contract objects you're aming at.

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.

It's plain stupid that you assume it should know it... thinking the way you do it's plain stupid we need to use all the different WB settings. How can the camera not know what's white ?!?

DavidM

 

[Victor Engel]

If you look at the bottom of the circle you drew on the picture,
the black and grey looking dirt is in focus. Follow this dirt to
the left and the tree trunk is in focus, as is the whole tree. It
seems everything in that plane is in focus. Don't know if he used
just a center focus point only or not. If he did, maybe what one
of the previous posters said is true, maybe the sawblade didn't
have the contrast needed but the black/grey dirt did? If he used 7
points, for the same reason he may have picked up the tree.

True, but it's not the circle that counts. It's the red bars that are the focus areas. Only a tiny sliver of the red bars is in focus. I think it's unlikely that the camera keyed in on that tiny sliver.

 

[Victor Engel]

Apparently yes ! We all appreciate the improvement of 10D's ability
to focus in low light situations, don't we ? So again - it did just
what it was designed to do. It found a contrasty ENOUGH object to
lock the focus on and so it did ! The only thing you seem to call
STUPID is that the camera doesn't KNOW which of those low contract
objects you're aming at.

Look at my previous post that shows the actual focus areas. There are no significant areas in focus in these areas. I'm satisfied that this picture illustrates a focus problem. Now if the camera consistently demonstrates a misfocus to the rear, sending it in to Canon for calibration should resolve the problem.

 

[Vern Stevens]

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.

VES

Godfrey

Well, after several shots, including the one below, I have pretty
much determined that my 70-200L 2.8 IS and my 10D make a nice
backfocusing couple. I suspect my 17-40L does it as well, just not
quite as easy to tell.

The following shot was done with the center focus point selected,
no recomposing of the frame. The chainsaw blade SHOULD have been
my focus point...



Full Image here: http://www.pbase.com/image/23652114/original

As you can see, the tree behind the stump and the ground behind the
blade are in focus, the stump, the chainsaw and it's weilder, all
in the same plane, are not in focus.

Time to call Canon.

VES

--
'Deceive, Inveigle, Obfuscate.' - The X-Files (Teliko)

http://www.pbase.com/vsteven

--
'Deceive, Inveigle, Obfuscate.' - The X-Files (Teliko)

http://www.pbase.com/vsteven

 

[Vern Stevens]

And I don't think they bode well from my problem...

All of these pics were center focus point selected and focused off of without reframing with one exception which I will explain later.



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.



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.



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?

VES

 

[Mark Gillett]

..on where the focus points were. If you look at the original, the centre of the pic is by the saw blade and tree trunk behind it. The sensor could well have covered part of the tree which it then decided to focus on because of the greater contrast.

Can you post the pic with focus points?

When you focus check that the desired focus point is what the sensor has picked up rather than assuming that is the case. They can often be fooled.

M

Can you post the pic with

Well, after several shots, including the one below, I have pretty
much determined that my 70-200L 2.8 IS and my 10D make a nice
backfocusing couple. I suspect my 17-40L does it as well, just not
quite as easy to tell.

The following shot was done with the center focus point selected,
no recomposing of the frame. The chainsaw blade SHOULD have been
my focus point...



Full Image here: http://www.pbase.com/image/23652114/original

As you can see, the tree behind the stump and the ground behind the
blade are in focus, the stump, the chainsaw and it's weilder, all
in the same plane, are not in focus.

Time to call Canon.

VES

--
'Deceive, Inveigle, Obfuscate.' - The X-Files (Teliko)

http://www.pbase.com/vsteven

--
http://www.pbase.com/markgillett

 

[Mark Gillett]

Leaves and grass do not have the contrast that the tree edge has.

M

...that this image proves backfocusing. Mind you, I'm not saying
that your camera and lens aren't back-focusing, but from what you
described, this could very well be correct focusing. If you check
the forum you will see that the ACTUAL focus area of the various
focus points are significantly larger than the rectangles displayed
in the viewfinder.

This is a good point, and I'm glad someone pointed this out to me.

Given this image, the saw blade (your focus
point) especially at the speed it is moving will be a low contrast
object, and the sawdust in the background immediately behind it
will provide much better contrast. That sawdust lies well within
the focus region of the center AF point. Given this, the camera
may have focused accurately on the wrong target.

I don't think the sawdust is clearly in the focus region. If
something other than the sawblade is in the focus region, it is the
leaves/grass in the background, which is also out of focus.

A far better test would have been to focus lock on the man and
recompose before fully depressing the shutter. Please do a search
on the focus areas - it's VERY enlightening and an understanding of
this has certainly improved my performance behind the camera.

= Ed =

Well, after several shots, including the one below, I have pretty
much determined that my 70-200L 2.8 IS and my 10D make a nice
backfocusing couple. I suspect my 17-40L does it as well, just not
quite as easy to tell.

The following shot was done with the center focus point selected,
no recomposing of the frame. The chainsaw blade SHOULD have been
my focus point...



Full Image here: http://www.pbase.com/image/23652114/original

As you can see, the tree behind the stump and the ground behind the
blade are in focus, the stump, the chainsaw and it's weilder, all
in the same plane, are not in focus.

Time to call Canon.

VES

--
'Deceive, Inveigle, Obfuscate.' - The X-Files (Teliko)

http://www.pbase.com/vsteven

--
= Ed Rotberg =

'A waist is a terrible thing to mind'
http://www.edrotberg.org/gallery

--
http://www.pbase.com/markgillett

 

[keef]

i never can understand why this issue causes so much debate

its very very easy:

i bought a lens last week

i used it

shots looked blurry

i did a test, very similar to the lens boxes 1-2cm behind, infront.

the test took 1 minute

i looked at the results

front focus problem

i returned the lenes and got a refund

if your regular shots suggest a problem, do a simple test with objects that are much bigger than the focus point. The regular photos suggest something. the test either proves it or disproves it. No squirrels. no monkey business.

http://www.waddo.net

keith

 

[DavidP #28649]

Yes, people act like they could SEE that amount of mis-focus through the viewfinder. It just isn't that easy to see.

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 .

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.

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

 

[DavidP #28649]

Apparently there WAS enough contrast, that's why it locked. How the
hell was the camera to know the photographer was aiming for the
blade not for the objects behind it ???

Actually, you're just assuming that this is what happened. You really have no clue as to what the camera thought was in focus. I can assure you there are times that the camera (in situations like this) will simply front or back-focus, when there's NOTHING else in the background to confuse it. So how would you rule that out in this case? You can't.

It's plain stupid that you assume it should know it... thinking the
way you do it's plain stupid we need to use all the different WB
settings. How can the camera not know what's white ?!?

Actually, there ARE ways to make the camera much smarter in this regard. Like the external WB sensor on the 1D. So, yes, it's stupid that the camera doesn't have one of these. What do you think it costs?

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

 

[DavidP #28649]

Two pics of a rock: The first was taken focused at 70mm then
zoomed in to 200mm to take picture.

Don't do that. Ever. If you're gonna try something like that, focus at 200mm, then zoom out to 70mm. NOT the other way around.

Even though Chuck Westfall claims the lens is parfocal "for all practical purposes", it isn't. As far as I can tell, none of the f/2.8 zooms are at any given subject distance. The technique of focusing long and zooming out wide CAN work sometimes. But it doesn't always.

I have shown that my 24-70/2.8 isn't parfocal at a distance of about 300 yards or so (essentially infinity). Now, I recently had this lens adjusted here locally for AF issues. I'll have to see if this has changed or not.

So, am I crazy, or is this backfocusing?

By definition it's backfocusing.

The question is, what's the CAUSE of it?

To find out if it's something that Canon can correct, you'll need to do some chart testing. I would NOT waste my time sending in camera and lens before doing such a test. If your camera/lens fail a test like Pekka's for Mishkin's (taken in good light), then you know Canon should be able to fix it.

If it passes such a test, then there's no reason to send it in. In that case, it's truly a case of "10D design error" / "user error". IOW, you'll have to figure out why it does these things, when it will happen, and how best (if possible) to work around the issue.

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

 

[DavidP #28649]

Exactly.

if your regular shots suggest a problem, do a simple test with
objects that are much bigger than the focus point. The regular
photos suggest something. the test either proves it or disproves
it. No squirrels. no monkey business.

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

 

[Mark Rodrigues]

ANY properly working camera that I have ever used will nail this shot - it is completely insane for anyone to make up excuses as to why the 10D should not be able to make this shot properly.

If a 1980's AF system can make this shot, then why can't the 10D ???

You zealots need to give everyone a break and stop making excuses for a crappy AF system.

And talking about critical focus - macro shots using an angle finder C, where critical focus is done manually, and focal plane is easily seen in the viewfinder ends up being OOF with my 10D and 50mm f1.4, so something is definately out of alignment with my 10D as well.

Is DavidP the only sane person on this site?

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).

it does lock but something that's behind the blade.

Isn't the camera smart enough to recognize when there's not enough
contrast?

Of course it's does. It has the 3.2Ghz on it an which compute in
split nanoseconds.

Apparently not. Even the 1D suffers from this . . . . apparently
not as frequently as the 10D, though.

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.

Hey, Dave have you try your 1D to focus on white wall? Better yet
try your 1D with the same shot so we can compare.

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.

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

 

[pixydust]

ANY properly working camera that I have ever used will nail this
shot - it is completely insane for anyone to make up excuses as to
why the 10D should not be able to make this shot properly.

Until you tried all then you can make such a generailized statement otherwise just a big IF.

If a 1980's AF system can make this shot, then why can't the 10D ???

You zealots need to give everyone a break and stop making excuses
for a crappy AF system.

We're not making excuse instead we simply excepted it limitation.

And talking about critical focus - macro shots using an angle
finder C, where critical focus is done manually, and focal plane is
easily seen in the viewfinder ends up being OOF with my 10D and
50mm f1.4, so something is definately out of alignment with my 10D
as well.

I can manual focus on the 10D with my eye closed. All I have to do is listend to the beep.

Is DavidP the only sane person on this site?

Plus a few other sane guys on this board spend all their time making chart and stuff. The rest of us those that are insane bought this camera and actually use to take real pictures.

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).

it does lock but something that's behind the blade.

Isn't the camera smart enough to recognize when there's not enough
contrast?

Of course it's does. It has the 3.2Ghz on it an which compute in
split nanoseconds.

Apparently not. Even the 1D suffers from this . . . . apparently
not as frequently as the 10D, though.

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.

Hey, Dave have you try your 1D to focus on white wall? Better yet
try your 1D with the same shot so we can compare.

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.

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

 

[pixydust]

It's plain stupid that you assume it should know it... thinking the
way you do it's plain stupid we need to use all the different WB
settings. How can the camera not know what's white ?!?

Actually, there ARE ways to make the camera much smarter in this
regard. Like the external WB sensor on the 1D. So, yes, it's
stupid that the camera doesn't have one of these. What do you
think it costs?

Why stop there? We can ask for spot meter and 45-point Area AF as well.

 

[Michael Louis]

to get back to you concerning 70-200 4L I told you I sent in for this exact same problem: backfocusing.

Just got it back Tuesday, went out yesterday and shot a quick 100 and man did Canon nail it!! Every single shot near and far is dead right on.

My trust in Canon has been well placed and now all 8 of my lenses are pinpoint accurate....even Wideopen.

Original poster, send this lens in and tell them to take their time. That's what I did. I explicitly told them to calibrate and then recalibrate. It took almost 3 weeks to get it back, but now I can look forward to years of joyous photographing (made up word)...

Two pics of a rock: The first was taken focused at 70mm then
zoomed in to 200mm to take picture.

Don't do that. Ever. If you're gonna try something like that,
focus at 200mm, then zoom out to 70mm. NOT the other way around.

Even though Chuck Westfall claims the lens is parfocal "for all
practical purposes", it isn't. As far as I can tell, none of the
f/2.8 zooms are at any given subject distance. The technique of
focusing long and zooming out wide CAN work sometimes. But it
doesn't always.

I have shown that my 24-70/2.8 isn't parfocal at a distance of
about 300 yards or so (essentially infinity). Now, I recently had
this lens adjusted here locally for AF issues. I'll have to see
if this has changed or not.

So, am I crazy, or is this backfocusing?

By definition it's backfocusing.

The question is, what's the CAUSE of it?

To find out if it's something that Canon can correct, you'll need
to do some chart testing. I would NOT waste my time sending in
camera and lens before doing such a test. If your camera/lens
fail a test like Pekka's for Mishkin's (taken in good light), then
you know Canon should be able to fix it.

If it passes such a test, then there's no reason to send it in.
In that case, it's truly a case of "10D design error" / "user
error". IOW, you'll have to figure out why it does these things,
when it will happen, and how best (if possible) to work around the
issue.

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

 

[DavidP #28649]

I would say that getting accurate WB on a digital SLR is much more a necessity than a luxury, that's why.

But, hey, I guess it's no big deal to spend lots of time fixing WB problems in PS.

It's plain stupid that you assume it should know it... thinking the
way you do it's plain stupid we need to use all the different WB
settings. How can the camera not know what's white ?!?

Actually, there ARE ways to make the camera much smarter in this
regard. Like the external WB sensor on the 1D. So, yes, it's
stupid that the camera doesn't have one of these. What do you
think it costs?

Why stop there? We can ask for spot meter and 45-point Area AF as
well.

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

 

[DavidP #28649]

Great.

I hope that my 24-70/2.8 and 16-35/2.8 will now function better. If they do, I may take my other lenses over to this shop to have them looked at, too. Well, except the 50/1.4 and 28-135 IS. Hardly worth spending $90 to make lenses that inexpensive focus correctly.

Right now, all I knows is that they "adjusted AF" on the two lenses (they didn't have my body), and that they also "adjusted infinity focus" on the 16-35/2.8

I may try tomorrow to go over and actually talk to the techs there to see what's really being done to accomplish these tasks. Might have to buy them lunch, but it'll be worth it.

to get back to you concerning 70-200 4L I told you I sent in for
this exact same problem: backfocusing.
Just got it back Tuesday, went out yesterday and shot a quick 100
and man did Canon nail it!! Every single shot near and far is dead
right on.
My trust in Canon has been well placed and now all 8 of my lenses
are pinpoint accurate....even Wideopen.
Original poster, send this lens in and tell them to take their
time. That's what I did. I explicitly told them to calibrate and
then recalibrate. It took almost 3 weeks to get it back, but now I
can look forward to years of joyous photographing (made up word)...

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

 

[Mark Gillett]

But it has found enough contrast in the log directly below the chain saw.

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).

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.

Isn't the camera smart enough to recognize when there's not enough
contrast?

As above!

Apparently not. Even the 1D suffers from this . . . . apparently
not as frequently as the 10D, though.

I know not.

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.

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.

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.

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

--
http://www.pbase.com/markgillett

 

[Michael Louis]

I hope that my 24-70/2.8 and 16-35/2.8 will now function better.
If they do, I may take my other lenses over to this shop to have
them looked at, too. Well, except the 50/1.4 and 28-135 IS.
Hardly worth spending $90 to make lenses that inexpensive focus
correctly.

Right now, all I knows is that they "adjusted AF" on the two lenses
(they didn't have my body), and that they also "adjusted infinity
focus" on the 16-35/2.8

I may try tomorrow to go over and actually talk to the techs there
to see what's really being done to accomplish these tasks. Might
have to buy them lunch, but it'll be worth it.

to get back to you concerning 70-200 4L I told you I sent in for
this exact same problem: backfocusing.
Just got it back Tuesday, went out yesterday and shot a quick 100
and man did Canon nail it!! Every single shot near and far is dead
right on.
My trust in Canon has been well placed and now all 8 of my lenses
are pinpoint accurate....even Wideopen.
Original poster, send this lens in and tell them to take their
time. That's what I did. I explicitly told them to calibrate and
then recalibrate. It took almost 3 weeks to get it back, but now I
can look forward to years of joyous photographing (made up word)...

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