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My 7D consistently BACKFOCUSES considerably

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Let´s see now, if it is that hard to see or come to a conclusion by testing your Tamron, is it really a problem IF it had backfocus? If you don´t notice it, whats the deal?

Almost feels like some paranoia.
Chadd Thompson said:
Well,

I may have to retract this statement. I just checked my lenses
again and it seems that a tamron lens I have may also be having a
problem with backfocus. It is much harder to tell though because it
is only an f4.5 so it doesn't have a super shallow DOF.
Click to expand...
 
The lens is soft to begin with and when you get a DOF of several inches it makes it difficult to tell. I will post some shots and let you decide if you think there are some sort of Back focus issues with the camera/lens combos.
SunKi said:
Almost feels like some paranoia.
Chadd Thompson said:
Well,

I may have to retract this statement. I just checked my lenses
again and it seems that a tamron lens I have may also be having a
problem with backfocus. It is much harder to tell though because it
is only an f4.5 so it doesn't have a super shallow DOF.
Click to expand...
Click to expand...
--
Thanks,
Chadd
http://www.pbase.com/chadd
 
Geir Ove said:
Hello,

I also started to suspect that my 7D foucsed in the wrong places,
so I decided to set up a test, the infamous Ruler test:
Click to expand...
After reading these posts I decided to test my lenses. Went to the Canon 10d,20D forum and found this link:

http://www.photo.net/learn/focustest/

This provides a chart that you can print out (I printed mine on 11x17) and then test each lens in a repeatable way.

So far I have tested four of my lenses with the following results:

Minolta 100 mm Macro - Focus right on (about 1/3 in front and 2/3 behind focal point).
Minolta 50 mm Macro - Focus Marginal Right at the Focal point and behind
Minolta 85 mm - Focused behind the Focal point
Sigma 180 Macro - Focus right on as with the 100 mm Macro
 
Here are test images I shot. All were tripod mounted, with center focus locked. I had to do autofix to correct bad auto WB out of camera so one or two of them are kind of noisy from pse3 adjustments, most have been cropped also.

If you want to see file descriptions go to my pbase under test images. These are from 4 different lenses I have.

Most of the results are acceptable to me except for the image that is the second down. That is a shot with the 50mm 1.7 from 8 feet. I cropped this one off to one side so you could acctually see where the focus point was. Look at that candle jar off to the left, it is at least 8 inches behind the paper test target that the camera was focused on and it will do it evertime at that distance and around that distance.

As you can see most of the lenses show some sort of backfocus. The best performers where longer focal lenght lenses. The 135mm 1.7 and an ond viviatar 70-210. Maybe this is a focal lenght issue?














SunKi said:
Let´s see now, if it is that hard to see or come to a conclusion by
testing your Tamron, is it really a problem IF it had backfocus? If
you don´t notice it, whats the deal?

Almost feels like some paranoia.
Click to expand...
--
Thanks,
Chadd
http://www.pbase.com/chadd
 
David 000 said:
Geir Ove said:
Geir Ove
David 000 said:
I have exactly the same issue as you and my camera is going back
tomorrow - see my posts under title "a frustrating week"

David
Geir Ove said:
Hello,

I also started to suspect that my 7D foucsed in the wrong places,
so I decided to set up a test, the infamous Ruler test:

Setup for both shots below:
  • Minolta 28mm 2.8 lens. Minimum Focus distance: 30 cm.
  • Camera set to Single Shot AF for one shot,
and Manual Focus for the MF shot
  • Aperture Mode, f2.8, s 1/60 Flash Used
  • Campera put on a tripod
  • Focused on number 20 on right side of Ruler in both cases.
Distance: 40 cm from camera lens.

Result:

Results repeated at least 10 times for AF with consistently the
same SUBSTANTIAL BACKFOCUS result! The number 30 is in focus!

My camera is going back. I will wait until KM fixes this. I so far
LOVE the rest of the camera and its imnage quality.

AF sample:

http://objective.bitfikler.com/geirove/web/temp_images/ruler_s_af.jpg

MF sample:

http://objective.bitfikler.com/geirove/web/temp_images/ruler_mf.jpg

Geir Ove

--
My album at: http://objective.bitfikler.com/geirove/web/
Click to expand...
Click to expand...
--
My album at: http://objective.bitfikler.com/geirove/web/
Click to expand...
Click to expand...
--
My album at: http://objective.bitfikler.com/geirove/web/
 
Aboiut "Learning Curve": I have used SLR cameras since I was 13 years old! What is there to learn: Put the camera on a Tripod, set AF to center focus and ask the camera to focus!

But I agree with you in one thing: It's probably not the lenses

Geir Ove
MrScary said:
Geir Ove said:
Hello,

I also started to suspect that my 7D foucsed in the wrong places,
so I decided to set up a test, the infamous Ruler test:

Setup for both shots below:
  • Minolta 28mm 2.8 lens. Minimum Focus distance: 30 cm.
  • Camera set to Single Shot AF for one shot,
and Manual Focus for the MF shot
  • Aperture Mode, f2.8, s 1/60 Flash Used
  • Campera put on a tripod
  • Focused on number 20 on right side of Ruler in both cases.
Distance: 40 cm from camera lens.

Result:

Results repeated at least 10 times for AF with consistently the
same SUBSTANTIAL BACKFOCUS result! The number 30 is in focus!

My camera is going back. I will wait until KM fixes this. I so far
LOVE the rest of the camera and its imnage quality.

AF sample:

http://objective.bitfikler.com/geirove/web/temp_images/ruler_s_af.jpg

MF sample:

http://objective.bitfikler.com/geirove/web/temp_images/ruler_mf.jpg

Geir Ove

--
My album at: http://objective.bitfikler.com/geirove/web/
Click to expand...
--I been following these threads about BackFocus problems with your
Lenses.....Logic tells me it can not be the Lenses that's at fault
because majority of you are useing different lenses..You can't tell
me that different lenses from same or different manufacturers are
ALL at Fault!!!!
It has to either be the AF in the Camera, or you all got a Big
Learning Curve with how to use this 7D..!!
MrScary (DennisR)
Swansea, Wales. UK

http://www.pbase.com/dennisr
http://community.webshots.com/user/mrscarecrow
http://digiden.photoshare.co.nz
Click to expand...
--
My album at: http://objective.bitfikler.com/geirove/web/
 
I am still dissapointed that we have to put up with this kind of innaccuracies with equipment in this price range. After all, what is a OUT OF FOCUS picture worth? AND, it is NOT Rocket Science to get a piece of AF system to work. We are daily surrounded with far more presice and complicated consumer electronics.

Geir Ove
Steve Eldridge said:
Geir Ove said:
Hello,

I also started to suspect that my 7D foucsed in the wrong places,
so I decided to set up a test, the infamous Ruler test:
Click to expand...
After reading these posts I decided to test my lenses. Went to the
Canon 10d,20D forum and found this link:

http://www.photo.net/learn/focustest/

This provides a chart that you can print out (I printed mine on
11x17) and then test each lens in a repeatable way.

So far I have tested four of my lenses with the following results:

Minolta 100 mm Macro - Focus right on (about 1/3 in front and 2/3
behind focal point).
Minolta 50 mm Macro - Focus Marginal Right at the Focal point and
behind
Minolta 85 mm - Focused behind the Focal point
Sigma 180 Macro - Focus right on as with the 100 mm Macro
Click to expand...
--
My album at: http://objective.bitfikler.com/geirove/web/
 
Sorry that should have read 135mm 2.8 and an old vivitar 70-210.

I wish that I had a local store that supported minolta, but all the local stores don't carry much if any minolta equipment including lenses. I would like to be able to test some other lenses on my body to see if it is mainly a problem with just this particular 50mm 1.7/body combo or if it is going to be a problem with other lenses also.

As I mentioned the results with the rest of the lenses are good enough for me, but the 50mm is unusable right now unless I use MF only with it.
Chadd Thompson said:
As you can see most of the lenses show some sort of backfocus. The
best performers where longer focal lenght lenses. The 135mm 1.7 and
an ond viviatar 70-210. Maybe this is a focal lenght issue?
Click to expand...
--
Thanks,
Chadd
http://www.pbase.com/chadd
 
My 50mm f1.7 focuses perfectly on my 7D. This is all very strange....
Chadd Thompson said:
I wish that I had a local store that supported minolta, but all the
local stores don't carry much if any minolta equipment including
lenses. I would like to be able to test some other lenses on my
body to see if it is mainly a problem with just this particular
50mm 1.7/body combo or if it is going to be a problem with other
lenses also.

As I mentioned the results with the rest of the lenses are good
enough for me, but the 50mm is unusable right now unless I use MF
only with it.
Chadd Thompson said:
As you can see most of the lenses show some sort of backfocus. The
best performers where longer focal lenght lenses. The 135mm 1.7 and
an ond viviatar 70-210. Maybe this is a focal lenght issue?
Click to expand...
--
Thanks,
Chadd
http://www.pbase.com/chadd
Click to expand...
 
What about trying out the same tests in the slow focus mode, it makes the focusing motor run slower. Although I am not suggesting that it would be a solution, it would be interesting to see if it would change the result. At least in the analog 7 there was a slow focus mode, is there such a mode in the 7D?

It is interesting to see that all new cameras seem to suffer from this problem to some extent...Nikon, Canon and now Minolta. How about Olympus e1? =)

-Thomas
Geir Ove said:
IF the Focus System uses an Open Loop Regulation Stepping Motor to
adjust the distance indicated by the camera AF system, then it
might step to far or short if the Stepping Motor Accelration /
Deceleration table is not carefully followed (How fast the Lens
Motor accellerates up to speed and slows down again to hit the
target posision: This depends upon load). This also explains how
one lens can work, and another NOT: IT depends on the LOAD the lens
exerts on the AF Stepping Motor.

From my last tests, it looks like the above can be the case: If I
put the lens at Infninity it backfocuses LESS than if it is preset
at the near limit before the test. See test results below.

If my assumptions here are correct, the AF motor is acrually to
blame. Since the lens contains NO LOGIC, I cannot see how the lens
can fail.

However, if the lens contains FEEDBACK of the lens position (Closed
Loop Regulation) , this feedback info may be innacurate and thus
some lenses may be to blame.

Focus preset at Infinity before focus test:

http://objective.bitfikler.com/geirove/web/temp_images/focus_preset_at_infinity.jpg

Focus preset at Near Limit (0.25 cm) before test:

http://objective.bitfikler.com/geirove/web/temp_images/focus_preset_at_near_limit.jpg
Click to expand...
 
I did a search on all forums on the word "backfocus" and got an huge amount of hits for Nikon, Canon and Minolta. Interestingly not a single hit for Kodak SLR for example. And the only hit on the Olympus form was this : http://forums.dpreview.com/forums/read.asp?forum=1022&message=9265155

Someone having a backfocus problem only when using a certain filter.

I wonder if this is due to the fact that people haven't tried it out, or if the Kodak and Olympus SLR do not suffer from it as much as the others.

Anyways, I think it would be intereseting to check some analog cameras the same way. Somehow I think this is nothing new.

This is an interesting thread to read, i think it tells a lot about the backfocusing problem in general:

http://www.robgalbraith.com/ubbthreads/printthread.php?Cat=&Board=UBB8&main=237060&type=thread

-Thomas
Geir Ove said:
Hello,

I also started to suspect that my 7D foucsed in the wrong places,
so I decided to set up a test, the infamous Ruler test:

Setup for both shots below:
  • Minolta 28mm 2.8 lens. Minimum Focus distance: 30 cm.
  • Camera set to Single Shot AF for one shot,
and Manual Focus for the MF shot
  • Aperture Mode, f2.8, s 1/60 Flash Used
  • Campera put on a tripod
  • Focused on number 20 on right side of Ruler in both cases.
Distance: 40 cm from camera lens.

Result:

Results repeated at least 10 times for AF with consistently the
same SUBSTANTIAL BACKFOCUS result! The number 30 is in focus!

My camera is going back. I will wait until KM fixes this. I so far
LOVE the rest of the camera and its imnage quality.

AF sample:

http://objective.bitfikler.com/geirove/web/temp_images/ruler_s_af.jpg

MF sample:

http://objective.bitfikler.com/geirove/web/temp_images/ruler_mf.jpg

Geir Ove

--
My album at: http://objective.bitfikler.com/geirove/web/
Click to expand...
 
level of service than Canon in getting these focussing issues sorted. Also sounds with Canon the issue is in the body and not the lenses..

I have every confidence that KM will sort these few teething troubles out quicky. The back focus on my D7D is so severe and constant that it should be pretty obvious to them what the problem is..

Apart from this one issue I like almost every other thing about the camera (apart from the pre-flash !) but then you can't have everything..

David
 
The backfocus issue has been a problem for my camera too - SN 00404634. I set the camera for slight in-camera sharpening.

My eye confirms the problem with my 85G and 50 1.4, 50 1.7.

It is far less pronounced with my minolta 35 1.4 and does not appear to be a problem at all with my sigma 24 2.8. Then again I am testing by sight through the view finder, camera screen and on my computer monitor. I am a compentent user of photoshop and know this is not something that will be solved by post-camera processing.

I purchased my camera from a local shop with an excellent repair faciilty - on purpose for just this kind of problem!

I intend to take the camera and several lenses to them tomorrow afternoon (US PST) for bench testing.

I hope there is a simple fix for this problem.

I agreed months ago to shoot a wedding for friends tonight. I had hoped to do it with the 7D but I am returning to my trusty 700si and film so I don't have to worry about messing things up. Weddings are stressful enought - at least for amatuer photographers like me.

Norme
 
Hello,

While focus problems is "nothing new" why should we put up with it? What is an out of focus picture woth? In my book nothing.

The electronics and presicion required to get AF right is NOT beyond reach: We are surrounded with everyday electronics which is both cheaper and more precise (e.g. Servo motors of Hard Drives not to speak of DVD players)

I find it unbelivable that DSLR users can ACCEPT that getting a lens to work on a DSLR should be something of a trial and error process with the prices we pay for the equipmen

Geir Ove
kiklop_2 said:
Well, guys, I’m sorry to hear about your problems. It’s been
anticipated that those who gets the first samples mayl be some kind
of beta testers.
Backfocus is unfortunately nothing new … I still remember all he
panic about Nikon d100 and canon 10d (not to mention 20D, or D70)

I hope KM will comment this issue and fix them.

I didn’t still receive my 7D. And guess what, I will gladly take
one of your samples camera … I’m that confident that KM will fix
that;)

Happy shooting

--
7D dedicated website http://www.dyxum.com
Click to expand...
--
My album at: http://objective.bitfikler.com/geirove/web/
 
Hey Geir,

bad foccusing can have many reason. It is too easy to blame the camera as the only possible reason. A german photo magazine did a focussing test with several cams some month ago. The conclusion of the test and some interviews with product managers showed, that there a several reasons for front- and backfocus. Here is a link to the german arcticle:

http://www.colorfoto.de/sixcms/media.php/258/0904Autofokus_cofo.pdf

Regards

Dat Ei
--
'Charter Member of the Konica Minolta 7D Adoption Society'
 
There is nothing magic to it. Set the AF to center point. Put camera on Tripod. Have good contrast target. Press shutter button and wait until camera confirms focus.

I have worked as an hardware engineer for years with lab testing and developoment. This is the camera's problem, or camera lens combination

Geir Ove
Dat Ei said:
Hey Geir,

bad foccusing can have many reason. It is too easy to blame the
camera as the only possible reason. A german photo magazine did a
focussing test with several cams some month ago. The conclusion of
the test and some interviews with product managers showed, that
there a several reasons for front- and backfocus. Here is a link to
the german arcticle:

http://www.colorfoto.de/sixcms/media.php/258/0904Autofokus_cofo.pdf

Regards

Dat Ei
--
'Charter Member of the Konica Minolta 7D Adoption Society'
Click to expand...
--
My album at: http://objective.bitfikler.com/geirove/web/
 
Hi!

Just a thought...
Have you (or anyone else) tried testing outdoors in good light?

I found this on dyxum.com:

"...in dim light, the 7D has the tendancy to overshoot a lot more often than the 9. And that's no wonder: not only is the 7D AF motor speed higher, also the AF sensors are less sensitive..."
(user testimonal from Leon van Bommel)

I suspect most of the testing people have done is indoors, so it would be interesting to hear if daylight makes a difference.

-Torstein
Geir Ove said:
I have worked as an hardware engineer for years with lab testing
and developoment. This is the camera's problem, or camera lens
combination

Geir Ove
Dat Ei said:
Hey Geir,

bad foccusing can have many reason. It is too easy to blame the
camera as the only possible reason. A german photo magazine did a
focussing test with several cams some month ago. The conclusion of
the test and some interviews with product managers showed, that
there a several reasons for front- and backfocus. Here is a link to
the german arcticle:

http://www.colorfoto.de/sixcms/media.php/258/0904Autofokus_cofo.pdf

Regards

Dat Ei
--
'Charter Member of the Konica Minolta 7D Adoption Society'
Click to expand...
--
My album at: http://objective.bitfikler.com/geirove/web/
Click to expand...
 
Hey Geir,
Geir Ove said:
There is nothing magic to it. Set the AF to center point. Put
camera on Tripod. Have good contrast target. Press shutter button
and wait until camera confirms focus.
Click to expand...
if things are that easy, why don't you develop your own cam? ;-)

You better start reading the article and try to understand how complex the problem is.
Geir Ove said:
I have worked as an hardware engineer for years with lab testing
and developoment.
Click to expand...
So what? Is this an advantage or disadvantage? If every hardware engineer would do no mistakes, we users would have no hardware to complain about.
Geir Ove said:
This is the camera's problem, or camera lens
combination
Click to expand...
You forgot to mention the possibilities of a general problem with that lens or a problem with your lens in particular...

Regards

Dat Ei
--
'Charter Member of the Konica Minolta 7D Adoption Society'
 
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