Hocus Focus Read This.....

Would you agree that this test is much better than a rock ? ))

I think that you have the EXACT same problem I do. Your back focusing even when you manual focus or autofocus. Perhaps you are correct in your finding that the focus shifts and this would prove to be a very impressive conclusion if you are correct. (as a newbie for me to see someone solve something like this is amazing to me)

Concerning the first picture (top resolution test pic).

When viewing the %100 image, look at the center resolution chart and find the smallest block where you can make out the 3 individual lines. From my perspective the smallest block on the center chart is number 3 for horizontal and number 2 for the vertical.

Now look at the chart on the right (farthest) and look at the same blocks and the blocks that are smaller. You can still see 3 individual horizontal lines all the way down to #4, and you can see the 3 vertical all the way down to number 3.

To me this means a Back Focus.

Take a look at the same relative blocks in each picture using the %100 view and you will see that the back box is always at least as good as the middle, and in most cases better.

Follow the blocks to the smallest block that you can still tell the difference between the 3 individual lines.

Tell me what you think about what I have said. Im still new to this all but I have spent 4 years of my life in Metrology. (science of weights and measures).

Now could you imagine trying to get that thing taped to the side of a wild animal while you check focus?

Canon told me they would have my camera back to me by the weekend even if it meant Saturday delivery

I will let you know what I find as this will be the first test I do. If it is fixed, I will post what I know about what happened.

Murph

Perhaps this knowledge does not apply here and I am incorrect. If I am, I would appreciate someone letting me know that I am reading those charts incorrectly.

Murph

C.A.S. said:

After shooting these last five shots I can truly say that the
problem is not with a focusing acquisition (sp?) but a focusing
holding problem.

I can tell that the camera/lens focuses right on the spot where I
want it to. The image in the viewfinder is just as sharp as the
manual focused one. But somewhere in the time between the shutter
being pressed and the photo being taken, the camera is moving the
focusing back just a notch.

Click to expand...

Interesting theory. However, it doesn't quite explain what I've seen with my 1D. At 135mm f/2 and 2.5m distance, my camera clearly front-focuses. (Or, possibly, as you say, focuses correctly initially, then the camera inexplicably adjusts the focus before firing the shutter).

Yet, if I moved to a closer distance (about 1.6m), I no longer see the front-focusing problem. I have a hard time explaining why this would be a repeatable phenomenon, given your theory. Ideas?

Have you tried moving even closer to see if/when the rear-focus issue goes away?

C.A.S. said:

This is the fifth time I have taken test shots like
these...although it's the first time using Murphy's chart...and I
can tell you that there is definately a focusing problem in MY
camera. I bet the majority of D60's DO NOT have this problem, but I
BET there are a few out there that do.

Click to expand...

I suspect it's a lot more than you do. I hope not, but I'm beginning to think so.

If you get the chance, try to keep moving closer and closer with the lens, to see if the rear-focus issue ever goes away at a close enough distance.

This is all very perplexing and disturbing.

--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise

Murphy said:

Would you agree that this test is much better than a rock ? ))

I think that you have the EXACT same problem I do. Your back
focusing even when you manual focus or autofocus. Perhaps you are
correct in your finding that the focus shifts and this would prove
to be a very impressive conclusion if you are correct. (as a
newbie for me to see someone solve something like this is amazing
to me)

Click to expand...

I'll agree with you that there is a back-focus problem. But I think my manual focus shot is dead on, tack sharp. The jpeg may not show it but the RAW/Tiff is dead on. I think that in manual focused shots the camera is dead on (or should I say, my eye is dead on).

As far as the resolution chart...it is very difficult if not impossible to determine resoultion via a jpg or a monitor for that matter. Different monitors are set up different and the final resolution is only as good as your monitor's fine pitch. The best detail I see on my monitor may not be the same in yours. The best and only way to see true resolution is to print the image from the original Raw/Tiff on good quality paper using a printers highest quality setting.

The only reason I used a rock in the first test was due to the fact that it was sitting on a bed of grass. The grass blades make for a great reference point to see where the focus plane is. When I used to shoot football I sometimes used the grass to make sure my shots were really in focused and if they were a "little soft" I would crop it out. Old sports shooters saying "The grass never lies."

Next test will be an open grass field where I can place three cones and shoot them the same way I shot the first tests. These will be the ones I will take to Canon and show them the problem.

--
Carlos

http://www.onestarimaging.com

Thank you for bringing the screen issue to my attention. I did not think that it mattered but I see your point.

Just 1 more step for me as I am learning all this.

I have not yet invested in a printer but I plan on getting the Canon s9000 as soon as I get a camera that focuses correctly. (Or shortly after).

I will make a point to do some experiments to learn about the problem with viewing images on a computer screen.

Murph

DavidP said:

Interesting theory. However, it doesn't quite explain what I've
seen with my 1D. At 135mm f/2 and 2.5m distance, my camera
clearly front-focuses. (Or, possibly, as you say, focuses
correctly initially, then the camera inexplicably adjusts the focus
before firing the shutter).

Yet, if I moved to a closer distance (about 1.6m), I no longer see
the front-focusing problem. I have a hard time explaining why this
would be a repeatable phenomenon, given your theory. Ideas?

Have you tried moving even closer to see if/when the rear-focus
issue goes away?

If you get the chance, try to keep moving closer and closer with
the lens, to see if the rear-focus issue ever goes away at a close
enough distance.

This is all very perplexing and disturbing.

Click to expand...

I tried the test once before at 20 feet and there was NO back focus problem. I think it has something to do with the mechanics of the AF system that there is some margin of error that works via percentage of error. Example....if the margin or error is 10%...at 40 feet it would mean that the error would be 4 feet...but at 120 feet that error now becomes 12 feet....if you went down to 10 feet the error would only be a foot and the DOF could mask it by including the error in the DOF. The closer you get, the smaller the error.

When the AZ Republic was beta testing the camera during the baseball playoffs, one of their photgs told Canon that all of their digital SLR's (The 1D and the D30) had a major front or back focus problem. Canon said that it was impossible since the focusing system was based on their film SLR cameras. Funny....no one has ever complained about film SLR's ever having front focusing problems. I think it is something about the digital format that makes the AF system work differentely and Canon just needs to figure out the bugs.

--
Carlos

http://www.onestarimaging.com

Murphy said:

Thank you for bringing the screen issue to my attention. I did not
think that it mattered but I see your point.

Just 1 more step for me as I am learning all this.

I have not yet invested in a printer but I plan on getting the
Canon s9000 as soon as I get a camera that focuses correctly. (Or
shortly after).

I will make a point to do some experiments to learn about the
problem with viewing images on a computer screen.

Click to expand...

No problem Murph...Your chart works great for showing a cosistent (sp?) pattern to use as reference. I was able to see the focusing areas pretty well on it. But as far as resolution, we need to make prints to see the real results....this test was just to see the plane of focus.

I will keep your chart on my files and I will use it for future resolution tests on prints.

--
Carlos

http://www.onestarimaging.com

Yes, the closer you get, the smaller the absolute error in distance. However, the closer you get, the smaller the absolute depth-of-field, too.

Therefore, I'd think that (if it's a constant margin of error) you'd see the front-focus or back-focus problems at any distance, if your theory of what's causing the problem is correct.

That's why I think my theory is more likely to be correct. Granted, it may be something completely different, or some combination, etc.

Whatever the reason, I sure wish we could somehow get more people who DON'T think they have a problem with front/back-focus to go out and do some testing like this. Those results would be most informative.

Statements by people that "well, I don't have any problems with it" don't mean much to me at this point. They may very well have the problem, but just have never shot in the conditions to see it. Or, like me (as I fear with my D30 and EOS-3), have simply attributed the problems they did have with it to their own technique or just "a bad shot".

Carlos Salcedo said:

I tried the test once before at 20 feet and there was NO back focus
problem. I think it has something to do with the mechanics of the
AF system that there is some margin of error that works via
percentage of error. Example....if the margin or error is 10%...at
40 feet it would mean that the error would be 4 feet...but at 120
feet that error now becomes 12 feet....if you went down to 10 feet
the error would only be a foot and the DOF could mask it by
including the error in the DOF. The closer you get, the smaller the
error.

Click to expand...

--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise

The front/back-focus issue will always be easiest to see when blown up to 100% on a monitor.

If you print to 8x10, it becomes harder to notice (though it's there).

That's a simple function of the DOF being dependent on the magnfication you use when printing/viewing. If you could print at the same relative size you're seeing on the monitor, it'd be easy to see in the print, too.

By the same token, small web-shots mask the problelm rather nicely. The DOF is larger, because of the smaller image size.

That's a little-known fact . . . that DOF depends on image magnfication.

Fortunately, it works to my advantage for simply posting web-shots of my pictures. However, I'd like to be able to PRINT 8x10's and be focused on the artist's face, not the microphone.

PS -- thanks to both of you for sharing your results in this matter. I certainly hope Canon CAN fix this problem, and that for some reason, mine just wasn't fixed the last time I sent it in. That would mean I can finally get it fixed, or get a new body.

Carlos Salcedo said:

But as far as resolution, we need to make
prints to see the real results....this test was just to see the
plane of focus.

Click to expand...

--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise

Carlos Salcedo said:

I shot this test once before and it did not work since I shot it
@f5.6...Damn 400mm f2.8 is so sharp at that setting that the shots
were hard to read....so...(scroll to the bottom of the page)

http://www.onestarimaging.com/test/focus.html

Here are the new shots at f2.8. I don't think anyone would argue
that the 400mm f2.8 L is very sharp even wide open. But it helps to
shoot wide open to make the DOF very small.

After shooting these last five shots I can truly say that the
problem is not with a focusing acquisition (sp?) but a focusing
holding problem.

I can tell that the camera/lens focuses right on the spot where I
want it to. The image in the viewfinder is just as sharp as the
manual focused one. But somewhere in the time between the shutter
being pressed and the photo being taken, the camera is moving the
focusing back just a notch.

Click to expand...

If that is the case, can you let it auto focus and then switch to manual before you release the shutter. Seems like that would be a good test.

C.A.S. said:

This is the fifth time I have taken test shots like
these...although it's the first time using Murphy's chart...and I
can tell you that there is definately a focusing problem in MY
camera. I bet the majority of D60's DO NOT have this problem, but I
BET there are a few out there that do.

--
Carlos

http://www.onestarimaging.com

Click to expand...

Zabar said:

If that is the case, can you let it auto focus and then switch to
manual before you release the shutter. Seems like that would be a
good test.

Click to expand...

I actually never thought of that. I will do that in my next test. I'm looking for a nice grassy lawn where I can set up a good test and show the results to Canon.

Thanks for the idea Zabar.

--
Carlos

http://www.onestarimaging.com

Unless, of course, the simple act of releasing the shutter button would still cause this focus shift.

Still, it could prove him to be correct.

It'd be hard to prove his theory incorrect in this manner -- though it would cast some doubt on it.

Zabar said:

If that is the case, can you let it auto focus and then switch to
manual before you release the shutter. Seems like that would be a
good test.

Click to expand...

--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise

DavidP said:

Whatever the reason, I sure wish we could somehow get more people
who DON'T think they have a problem with front/back-focus to go out
and do some testing like this. Those results would be most
informative.

Statements by people that "well, I don't have any problems with it"
don't mean much to me at this point. They may very well have the
problem, but just have never shot in the conditions to see it. Or,
like me (as I fear with my D30 and EOS-3), have simply attributed
the problems they did have with it to their own technique or just
"a bad shot".

Click to expand...

I have shot so much with my film cameras that I can tell right away if there is a problem. I think my EOS 1V and the 400mm f2.8L is my sharpest combo. The results of this combo with a good slide film is incredible. The focusing has never let me down. It sometimes amazes me.

I will keep you guys informed on my future tests.

--
Carlos

http://www.onestarimaging.com

DavidP said:

Unless, of course, the simple act of releasing the shutter button
would still cause this focus shift.

Still, it could prove him to be correct.

It'd be hard to prove his theory incorrect in this manner -- though
it would cast some doubt on it.

Click to expand...

It's worth the shot...the least that it would do is waste a few more frames....and you never know...

--
Carlos

http://www.onestarimaging.com

Do you still have the 1v ? If not, can you borrow one?

I'd love to see some testing with a film camera, done side-by-side with the digital (well, adjusting the distance accordingly to keep the framed subject the same size).

I don't have my EOS-3 anymore. I'm trying to see if I can get a friend's Elan to test with this weekend.

Carlos Salcedo said:

I have shot so much with my film cameras that I can tell right away
if there is a problem. I think my EOS 1V and the 400mm f2.8L is my
sharpest combo. The results of this combo with a good slide film is
incredible. The focusing has never let me down. It sometimes amazes
me.

Click to expand...

--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise

Definitely do the test . . . as will I.

Who minds wasting digital frames?

Carlos Salcedo said:

It's worth the shot...the least that it would do is waste a few
more frames....and you never know...

Click to expand...

--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise

I tried to manually focus on the Pop-Tarts box using a focusing screen with a split-screen focusing aid. The results were actually worse than using the auto-focus.

Another idea I tried was putting the focusing sensor over the edge of the box (with only one box in the frame). I thought maybe the sharp edge of the box against the background would be easier for the AF to pick up.

Unfortunatel, this also resulted in an out-of-focus shot.

--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise