Focus Problems

Some of my photos are perfectly in focus and others are off. How can I tell if my 10D is one of the ones with the infamous focus problem???

A few links to get you started.

http://photography-on-the.net/forum/viewtopic.php?TopicID=10948

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

Good Luck,
Dave

sdirghalli said:

Some of my photos are perfectly in focus and others are off. How
can I tell if my 10D is one of the ones with the infamous focus
problem???

Click to expand...

sdirghalli said:

Some of my photos are perfectly in focus and others are off. How
can I tell if my 10D is one of the ones with the infamous focus
problem???

Click to expand...

The infamous 10D focus problems are consistent in nature, either front focus or back focus. If you are finding some in focus and some out of focus then it is probably technique.

--

Rule books are paper they will not cushion a sudden meeting of stone and metal. Ernest K. Gann

it is usually tied to particular lenses, although some have experienced across the board problems. Also, even on the same lens, stopping down enough will often yield acceptable images, thus giving the illusion it works sometimes and sometimes it doesn't, until it is investigated more closely. Cindy

EOSThree said:

The infamous 10D focus problems are consistent in nature, either
front focus or back focus. If you are finding some in focus and
some out of focus then it is probably technique.

--
Rule books are paper they will not cushion a sudden meeting of
stone and metal. Ernest K. Gann

Click to expand...

--
CindyD or SarahD
If one of us is laughing, and the other one isn't, one of us must be wrong...

sdirghalli said:

Some of my photos are perfectly in focus and others are off. How
can I tell if my 10D is one of the ones with the infamous focus
problem???

Click to expand...

post pictures of what you think is a problem.

chances are if some of your pictures are in focus, then there is no problem with camera. it's most likley user error along with the other 98% of users that report a problem.

so post your shots, exif included, with lens, and maybe how far you were.

---Mike Savad

--
http://www.pbase.com/savad/
http://www.photosig.com/go/users/view?id=9050
http://www.artsig.com/go/users/view?id=52

I gave up on using the 7pt system. I choose one focus point, usually the center one, set the focus with the * button (Custom Function 4.1), and then recompose and take the photo.

I made that move long ago...I still get some focus problems. The frustrating part is that some of the shots are perfectly in focus others are off.

Juli Valley said:

I gave up on using the 7pt system. I choose one focus point,
usually the center one, set the focus with the * button (Custom
Function 4.1), and then recompose and take the photo.

Click to expand...

sdirghalli said:

Some of my photos are perfectly in focus and others are off. How
can I tell if my 10D is one of the ones with the infamous focus
problem???

Click to expand...

--

Generally, and according to my experience, if you have some images in focus and some out then the camera body is unlikely to be the problem.

The other factors to take into account are the lenses used, the apertures, light levels, shutter speeds and general technique.
Paul

sdirghalli said:

Some of my photos are perfectly in focus and others are off. How
can I tell if my 10D is one of the ones with the infamous focus
problem???

Click to expand...

Another source of inconsistency is the famous "sensor-is-larger-than-the-focus-rectangle" issue discussed at length in this forum. The "out of focus" shots might have some focus attracting detail just outside of the red focus rectangle. Do a forum search to find the details about this issue.

Post your shots... in focus, out of focus.

How many focus points are you using? In what kind of light? Which lens?

Until then, search the forum.

Assuming it's working correctly the front or back focus can vary across a whole depth of field. So worst in spec case is you may take a shot which backfocuses by 1 dof, then the next shot may front focus by 1 dof. More likely is that a given lens varies by about half of that whole 1 dof tolerance. A lens like the 50mm 1.4 seems to often be reported as out by more than others.

If the problem were consistent, it would be very easy to fix, so you'd expect to end up with perfect focus.

You can see very good consistency when shooting test targets at short distances, by go up to 40x or 50x focal length and the variance per shot is quite big.

Regards,
Kev

EOSThree said:

sdirghalli said:

Some of my photos are perfectly in focus and others are off. How
can I tell if my 10D is one of the ones with the infamous focus
problem???

Click to expand...

The infamous 10D focus problems are consistent in nature, either
front focus or back focus. If you are finding some in focus and
some out of focus then it is probably technique.

--
Rule books are paper they will not cushion a sudden meeting of
stone and metal. Ernest K. Gann

Click to expand...

My camera is in Irvine right now for the second time. The Canon reps have been awesome trying to accomodate me right now. I had extensive talks with two techs and they say the information at the link below is a valid test although there are people that will say different. The people at the 800 number explained the ruler setup to me and as for the box setup I believe that came from a poster called 1ofus!.

I have not told anyone about this link yet as I am waiting for the after results once I get the camera back but you are welcome to take a look. If there is a front or back focus problem you will see it immediately
Good luck and let me know if I can help
http://home.comcast.net/~samd/dslr.htm

--
Taking life one picture at a time
http://www.pbase.com/samd12

Sammy, Sorry this has been so frustrating for you. I don't think I suggested that box test, although it sounds fine if done correctly.

The problem with tests and angles - try this - on your ruler test level your tripod aligned with marks on the target - take a test shot. Repeat 2 more times with the tripod raised (or moved slightly side to side depending on if the scale is up and down or sideways) and the camera tilted down or over to align with the marks, repeat in the opposite direction. You will probably get 3 different results . . . this could leave a person with a bad lens thinking it is actually good, or vice versa. Tests need to be conducted carefully and an angled target makes it very hard to do that. The angle on the ruler could throw off how the DOF lands on the scale. Also, maybe not you, but many people will get too close because the scale is hard to read. Even on the box test the camera needs to be level . . .

When I first started doing focus tests they were criticised as not accurate (photo.net scale). As I started doing better tests more carefully the results actually got worse (mostly I think because I moved back to 50X focal length). . . but I think the opposite could happen too. Also, would strongly suggest using Av and your widest aperture rather than auto.

Anyway, the upside of going through this is you learn a lot (like how SERVO can improve focus), I know I have. Sorry this forum hasn't been more help to you. Good luck with your gear. Cindy

sammyd said:

My camera is in Irvine right now for the second time. The Canon
reps have been awesome trying to accomodate me right now. I had
extensive talks with two techs and they say the information at the
link below is a valid test although there are people that will say
different. The people at the 800 number explained the ruler setup
to me and as for the box setup I believe that came from a poster
called 1ofus!.
I have not told anyone about this link yet as I am waiting for the
after results once I get the camera back but you are welcome to
take a look. If there is a front or back focus problem you will
see it immediately
Good luck and let me know if I can help
http://home.comcast.net/~samd/dslr.htm

--
Taking life one picture at a time
http://www.pbase.com/samd12

Click to expand...

--
CindyD or SarahD
If one of us is laughing, and the other one isn't, one of us must be wrong...

I appreciate your help up until this point. Looking back at the posts it was "keef" who suggested the box technique, I knew you had tried to help in there and got things confused. Anyway I have had extensive conversations with Canon service and from what they said I believe they feel with everything I did the chance of it being just user error was taken down to it's smallest possibility. I will know very soon and believe me I will fill you in either way. I must say that with everything I am going through the Canon service reps have been great to deal with. They have really gone the extar mile this time and it does make me feel better about things.
--
Taking life one picture at a time
http://www.pbase.com/samd12

While I appreciate the need for 10D shooters to test their camera’s ability to focus, I’m at the next step...I know it has a focusing problem. Has anyone sent their camera in to Canon to have it fixed? How did that work out?

Thanks