Canon 20D close focus problems

[drh681]

Oh, I suspect that a lot of times, this kind of thing goes missed(in those FEW uints with the problem) because most folks never leave the "auto everything" mode and get enough DOF to cover; then add in some sharpening when printing...
... no obvious problem!

[budjames]

I have a 20D which replaced a 10D. The 20D focusing is much faster and more accurate than the 10D. I have never experienced the problems you describe with my camera.

I also have a 1D MkII. This camera focuses even quicker, but the 20D is still very good.

My 2 cents.

Bud

[drh681]

not much for statistics are you.

or up on manufacturing process.

I have no complaint of these lenses on several different film bodies. so why would they all of a sudden be out of adjustment on a digital body?  and again I ask, why none of them will work with this body? five different lenses, bought over several years, and ALL of them are out of adjustment?
NOT LIKELY.

here is what I guess; Canon has moved the assembly of these bodies to an off shore plant. to facilitate the huge increase in unit volume they are using assembly jigs and sub-assembly of certain components(sensor+mirror box) and someone is passing that sub assembly at one limit of tolerances, while someone else is passing the body assembly at the opposite limit of tolerances. So both sub-assemblies "pass" their inspections; but together wont close focus.
Note: this is just one possible scenario.

[Eric Myrvaagnes]

drh681,

I guess what bothers me is this question: Why are no other 20D owners jumping in and saying "Yes, my camera also has close focusing problems?"

To me it sounds very unlikely that you would be the only 20D owner on the forum to have this problem unless it is some problem with your procedure. Yet you sound like a competent and experienced photographer, so that seems unlikely.

It also sounds absurdly unlikely that one person would get three bad 20Ds in a row.

And it certainly seems absurdly unlikely that five leses bought over a period of years would all exhibit the same focusing problem now.

As Sherlock Holmes would say, now that we have eliminated all the impossibilities, what remains? Darned if I know. It is baffling. Can we see some sample pix?

Eric

[Jonathan Wienke]

I'm sorry, but you seem to be nuts.
An inch of focus error is not the way any camera manufacturer maintains a reputation for quality.
And this whole thing started because of the poor results I was getting when shooting close ups! You also seem to imply that it is OK for the 20D to not perform certain aspects of photography.

That depends whether the inch of focus error is in a wide angle shot with the subject 30 feet away, or a macro shot with a 6-inch subject distance. The latter instance would be indicative of a problem, but the former would not. You've yet to post a sample image showing what you're complaining about, so it's not possible to tell whether your issue is a (a) hardware problem, ( user error, or © unrealistic expectations that are more appropriate for a 1-series camera with a much faster and more accurate AF system that functions well in much lower light levels than the consumer-grade AF system of the 20D. At this point, given your refusal to post sample images and your general intransigence, IMO B and/or C are the most likely explanations, rather than some massive Canon QA lapse.

If you want to solve the problem, send your camera and lenses to Canon to make sure everything is calibrated properly, because camera and lens calibration are equally important for proper AF operation. If you're not willing to do that, then at least have the courtesy to take your bad-tempered rantings elsewhere. If you're not going to take reasonable steps to solve the problem, then you have no right to complain about it.

[boku]

Boku: if you have something germain to this discussion, add it in.
If you are just trying to pick a fight with me about how I characterized a fallacious point by someone else, butt out.

No problem - I will leave you alone - forever. I didn't bother with anything germain because you weren't receptive.

[Ray]

Having spent a bit of time over the years testing my lenses against test charts with lines, I have found that these provide a very graphic and immediate indicator of whether or not a lens is focussing precisely at close distances.

The first proper test chart I photographed was one I'd downloaded from the Norman Koren site. I'd assumed that focussing would be a major problem and that I'd have to manually tweak the focussing. Any test results that are not precisely focussed are of course useless.

I was surprised to find that autofocussing was not a problem. Provided the lines  are sufficiently close, at least on some part of the chart, when the lens is in focus there'll be a blaze of color aliasing and aberrations.

The only lens I came across that didn't produce that effect was an EF-S 10-22mm. I had to manually tweak the focussing to get the effect (color aberrations). I considered this lens had a focussing problem and returned it. At close distances, about 1 metre and at 15mm, it was focussing behind the target and the misfocussing was obvious in real scenes.

[Jonathan Wienke]

Jeez, is that the long way of saying that the lens turns until the camera tells it the image is sharp?

No, just an explanation of why lens calibration as just as important as body calibration, but there is no focus adjustment screw for lenses.

[drh681]

believe what you will...

I know the difference between camera shake and a missed focus. I also tried using a tripod.(that was the tipping point)

and a front focusing camera will front focus in "manual focus" too.

as for the diopter adjustment... what can I say? I wear bifocals and with those I only needed a small neg adj. to get the focus points and viewfinder info display sharp.

I have used EOS cameras for more than seven years; and I sold them(and others) for five years. I did not just fall off the Point-and-shoot, CEVT turnip truck!

I am amazed at the presumptions people make in response to reported problems with "their" favorite brand of whatever!

EOS 20D-c is at Canon now for "adjustment" I also left a brand new 100ƒ2.0 and year old 50ƒ1.8 for "calibration" (which I think they recommend to cover the cost of the "adjustment"! )

[drh681]

press the shutter halfway and look for the swirl of colors.

yeah, it was just for a smile.  

Well I'm off to "Irving"...

oh wait, that is in Texas...

what is the name of that place down there by Costa Mesa?

[drh681]

sorry for the late reply;
I went out of town.
yeah, two bodies were seqential numbers, I was not surprised that there was the same problem.
I am fetching the third body from Canon today. If there is a report to go with it I'll put the gist of it up here too.
D.

[ARD]

My 20D has the same problem, maybe just a defective batch, but they will sort it so no problem

[Jonathan Wienke]

If you're on your third body, it's likely that the focus calibration of the lens you're using needs adjustment, and your triple body exchange has been an entirely unnecessary waste. When having such issues, the best thing to do is to send everything involved to Canon and let them figure out what components are out of adjustment and make appropriate adjustments.

[guitarman]

not much for statistics are you.

or up on manufacturing process.

I have no complaint of these lenses on several different film bodies. so why would they all of a sudden be out of adjustment on a digital body?  and again I ask, why none of them will work with this body? five different lenses, bought over several years, and ALL of them are out of adjustment?
NOT LIKELY.

here is what I guess; Canon has moved the assembly of these bodies to an off shore plant. to facilitate the huge increase in unit volume they are using assembly jigs and sub-assembly of certain components(sensor+mirror box) and someone is passing that sub assembly at one limit of tolerances, while someone else is passing the body assembly at the opposite limit of tolerances. So both sub-assemblies "pass" their inspections; but together wont close focus.
Note: this is just one possible scenario.

I would just like to take this opportunity to thank the offshore worker for doing a very good job on my 20D.

[Jonathan Wienke]

Because you're insinuating pretty strongly that Canon has a systemic manufacturing problem, which if true would mean that problem would negatively affect most 20D owners. Given that most 20D owners are not having focus problems, your thesis appropriately falls in the "exceptional claims require exceptional proof" category.

The other thing you're completely ignoring is that you're whining about focus errors that in most cases are less than an inch. The consumer-grade bodies have a lower-cost AF system that is not designed to focus as precisely as the higher precision, but much more expensive 45-point AF system found in the 1-series cameras, which is part of the reason they cost $4000+ instead of under $1600. Without seeing your sample shots, there's no way to tell, but an inch or less of focus error could be well within the acceptable error tolerance of the 20D AF system design. Except for macro work (which is generally manual focus anyway) and some wide-aperture portraiture, in most real-world shooting conditions a focus error of an inch or less is irrelevant. What are you shooting where an inch of focus error is making the difference between an acceptable and an unacceptable capture?

[boku]

I'm sorry, but you seem to be nuts.

You have, as of this writing, 8 posts. You are clearly antagonistic. You don't want to hear about real life logic and expectations.

Many people come here and start off this way. Some fade away, some open their ears. What's it going to be?

[Jonathan Wienke]

So, Jonathon is the only person that knows how to properly operate and EOS system camera? My only real "expectation" for this camera, is that it would as well as my Film EOS cameras, such as focus where I put the active focus point.
You keep harping on adjusting the lenses, I dont see an adjustment screw on any of them. My guess is that any "adjustments" will be made to the sensor mount in the camera. something that should have been done before shipping!

Again, you're displaying your ignorance of how the Canon AF system works. While there are AF mechanical adjustments involved in the body to synchronize the focal planes of the viewfinder, AF system, and sensor, it is unlikely that is the issue, as that would cause a consistent degree of focus error at all distances, whether focusing manually or via AF.  There are also firmware lookup tables in the body that the AF system uses to calculate the optimal focus distance given the phase error signal magnitude from the AF sensors (which need to be tweaked to match the individual characteristics of the AF sensors), as well as an additional set of lookup tables in the lens firmware that maps the relationship between focus ring position and the corresponding focus distance. Even if all of the mechanical adjustments are perfectly aligned, if the lookup table data in either the body or the lens is incorrect you will have AF accuracy problems. If the body tables are off, the body will send the wrong focus distance to the lens. If the lens tables are off, the lens will move the focus ring to the wrong position for the body-specified distance. There are no adjustment screws for the firmware lookup tables; it's all done via diagnostic equipment that only Canon has. So you absolutely do need to send your lenses and bodies to Canon to ensure all possible problems are addressed.

[drh681]

Jeez, is that the long way of saying that the lens turns until the camera tells it the image is sharp?  

I have said that there are consistant front focus errors.(at least I'm pretty sure I have.) At longer distances the error is greater, farther in front and deeper, but less noticable due to the wider DOF.
Some of the baseball pictures I made last night will make nice enough prints with a bit more than average sharpening.

I dont recall if I have said so, but I will have this camera adjusted, but Canon is closed til 5 July, and I got other things to do that particular day.

But it will go. My gripe is, that it has to.

my real suspicion is that in their haste to meet shipping commitments for the Father's Day/Graduation selling period;(traditionally strong for cameras, that is why Ritz hangs one of their bi-annual catalogs there) Canon loaded containers with a production run that included units that would ordinarily have been re-worked in house; or worse, were not even benched before they were boxed. The production run for 20D bodies has been HUGE for a piece of equipment of such comlexity.(roughly double the run for 10D)

Boku:
sorry to have offended you, but you came in and tried to push me around for how many posts I have. that is not exactly a friendly thing to pull an a recent arrival is it?
you may guess from this, that I am not un-familiar with photo oriented bulletin boards. I was not taking offense at Jonathon's comments, other than his presumption that my problems had to be "user error".
 

[Ray]

okay, but why a magic number?

No magic number required. However, if the lenses compared are of the same FL, you don't even have to shift your tripod. Just change the lens, press the shutter halfway and look for the swirl of colors. You could go through all your lenses this way, keeping the target the same size in the viewfinder.

I'd really like you to try this. You might find a lens that focuses perfectly on the target yet doesn't produce the chromatic aberrations   .

[Ray]

Sorry! The local humour is lost on me. I'm in Australia.

When you get your 20D body back from Canon after it's been adjusted, I highly recommend the method I've described for checking if your lenses focus properly at close distances. It's better than a fresnel focussing screen with magnifier in this instance. You just have to make sure you have lines on the chart which are beyond the resolution limit of the sensor and are challenging the resolution limits of the lens itself. I assume this effect results from imperfections in the lens (no lens is perfect) or maybe it's a combination of imperfections in the lens, mirror and viewfinder. Whatever, the effect disappears if the lens is the slightest bit out of focus, which would suggest it's all in the lens.