Luminous Landscape Forum
Equipment & Techniques => Digital Cameras & Shooting Techniques => Topic started by: drh681 on July 01, 2005, 03:56:21 pm
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right. five lenses(all EOS) "out of adjustment".
think it through, If it were the lenses, would not at least ONE of them been "in adjustment"?
For background, I have been using EOS stuff for seven years(I sold it for five), I know how most of it works and have not, until now, been baffled by a quality control problem.
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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.
The flaw in your theory is that most other 20D owners would be screaming about focus miscalibration if it had any basis in fact. I still think the most likely cause is user error, especially since you haven't posted any sample images or any explanation of your test methodology. In addition, Canon DSLRs are focus calibrated as a completely assembled unit with a "tool lens" that is used as a known good focus calibration reference. So your guess is pretty far off base.
As to my understanding of statistics, I have a prettty firm grasp of the obvious. Yes, 5 lenses out of adjustment is more unlikely than three bodies, but your argument regarding those lenses working fine on film bodies is totally worthless. Digital is much less forgiving of focus errors than shooting with film because digital sensors record more detail per area unit than film. In addition, people are enlarging digital images much more with digital than with film; when was the last time you made a 24x36 inch print from 35mm film? I do so regularly with 1Ds images, and so do you if you view your images at 100% in Photoshop. The more you magnify an image, the smaller your effective CoC becomes, and DOF shrinks accordingly. So with digital, you're able to appreciate focus miscalibrations of less than an inch that used to be buried in the film grain. It's the same reason that 1Ds owners complain about lenses that used to be highly regarded in film days. The sensor captures so much more detail than film that lens aberrations like CA and coma and suchlike that were smaller than film grain structure are being revealed in all their glory by the unforgiving slab of silicon.
Post your test methods and some sample images.
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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
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.
I do indeed say that there is a problem in the late production run of 20D bodies.
A problem that as you say, may go un-noticed in the run of snapshot photography. But it is a problem that should not have shipped.
Snapshots are what I have a Minolta S414 for!
A point of logic:
using manual focus through the view finder will not get a focused image on the sensor; if the sensor is out of the plane of focus! you can focus with 20/20 vision all day and still have front focus. Believe me I have tried.
Auto focus works on sensing the difference between light and dark in your subject. these sensors are not in the film/sensor plane, they are in the periphery of the mirror box. so if the mirror and sensors are correctly positioned, you will see a focused image in the view finder, and get a focus lock signal but still have front focus due to a misalignment of the image sensor.
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drh681,
Sounds to me like you're doing everything correctly. You're performing a variety of tests over three bodies and multiple lenses. If you can consistently repeat your findings then the next step may be to contact Canon directly.
I've worked in the software industry for twenty years and, at this point, I am never surprised when a released product that has been in the field for years suddenly hits a bug by one customer who is doing everything correctly. Actually, it happens all the time. You often find that a slight variance in circumstances (a linkage library definition being slighty changed) can cause a world of difference.
Also, it may simply be a bad batch. The fact that the serial numbers are so close together seems to lend weight to that argument. As they say in the automotive industry "Don't buy a car made after lunch on a Friday".
As for forum members who take themselves too seriously, ignore them. You run across insecure people who overcompensate by belittling others and trying to dominate conversations in all aspects of life. The internet just gives these people a permanent home. If you don't believe me, then the next time someone dumps on a person who is just asking a question or is expressing a sincere opinion, check the number of posts for the dumper. You'll usually find a very large number that screams "Love Me Daddy" for all to hear.
Thanks,
Heavysigh.
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Jeez, is that the long way of saying that the lens turns until the camera tells it the image is sharp?
Not only that, but it's a good method of analyzing how much manual adjustment is required to bring the target into precise focus, without having to download the images and peer at them on the screen. If you have more than one lens of the same focal length, which is quite likely if you have a number of zooms, you can quickly see if if they all behave the same at a particular FL and distance from the target.
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(http://www.phototalk.net/photos/data/556/35LaFlordeluz.jpg)
Oh Wow!
:laugh:
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I want to thank everyone for their input.
This unit is going to Canon for "adjustment"
and is not being used for any critical work until it comes back and passes the test.
For those wanting to lay the problem on the lenses, I made some of the same images on film last week, and had no signs of the front focus problem.
It is easy to presume a user interface problem with newly aquired equipment. Indeed the few things I have used it for have pointed up a slew of "doofus factor" points. (mostly in remembering to reset white balance, etc.) I was doubting my camera handing skills myself till I decded I had done everthing as usual with the only variant being the camera body.
These discussions have helped me sort out my thoughts.
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the camera and 100mm are covered, the fifty is going to be 40$.
no offence taken, I understood your reply.
I have noticed that on many boards there is a tendency for the first responders to presume that the poster is "not doing something right".(a fair presumption often enough) I had that go-round with Jonathon. In fact the only offence I took was when someone tried to pick a fight with me for standing my ground then.
I welcome comments and wont take offence to didactic questioning.(I do it myself some time, but I try to keep it more in the nature of a check list)
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Great! Looks to me as if they moved it from really yucky to really usable. Glad it worked out well.
Eric
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The question arises of course, just how many cameras (and not just the 20D) are slightly out of adjustment to a degree that's not as obvious as in the above example, giving the impression to the owners that slight misfocussing is normal and unavoidable with their quality of camera.
Not that I'm trying to create a panic..... :D .
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I have been having problems with front focusing when the subject is within six feet or so.
the first two cameras were only one s/n apart. this third body is weel off that sequence but still has a front focus of one half to one-and-a half inches in front of the selected focus point.
Am I missing some info about a "design feature"?
After two returns, I agreed with the seller that I would deal with this through Canon if it showed up in the third. So tomorrow is for Canon techhelp; but it really gripes me that I need to send a camera for "adjustments" right out of the box!
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That's not much more off the wall than 3 consecutive bodies "out of adjustment". What's even more likely at this point is some type of flaw in the test methodology, or other user error.
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when was the last time you made a 24x36 inch print from 35mm film?
well... 20x30s about 3 years ago. some from ISO 800 and 1600, I know what film grain is and what can be made out of it.
as for the method, I used the oft posted 'target on a 45° rule' method. in filtered daylight and under flash with a tripoded camera. for a "real life" test I used a set of three staggered film boxes and focused on the center box. Center focus point selected.
plus a few dozen flowers and tiny things.
it was the flowers that actually tipped me off. I had no Idea that this was an issue. as you say, small errors in focus point do not show up in longer veiws with their much greater DOF let alone the consequent smaller apertures. even close up the zone of appearent sharpness will extend past the target at small apertures. BUT the actual focus point is still in front of the target.
trust me, it is not a 'sharpness issue' either, I know my lenses and what I can expect of them, and what not to expect. They are not L lenses, but they are not the mediocre kit zooms either.
I have a prettty firm grasp of the obvious. Yes, 5 lenses out of adjustment is more unlikely than three bodies,/I]
you miss the point that the three 20D bodies were all made in the same place and in the same time frame.
to have all the lenses, manufactured over many years, and possibly in different places, showing "focusing errors" would indicate a VERY long term Q.C. problem at Canon. again, not likely.
why are you busting my chops?
you dont even use the camera!
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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.
Eric, I've also had similar problems, but I choose to believe that it's a sum of the inherent lack of precision in the focusing system of the 20D, combined with a viewer that is lacking (at least compared to my old 650) in terms of showing when I've got focus, and again combined with lack of precision in wetware*.
My most notorious personal example was a series of test shots of the EF 50mm f/1.4 USM. I attempted to take shots of a cueball on a pool billiard table under excellent lighting conditions, using a tripod and autofocus (followed by locking to manual focus).
The camera focused a couple of inches behind the cueball, and I didn't notice. It was impossible to see on the LCD, too.
I'm not claiming that this is the case for drh681, though it certainly can happen.
Other embarassing moments have occurred when a finger has changed the diopter adjustment ...
* Wetware is, for those who aren't familiar with the term, basically the human neural system, including the brain.
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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.
uh... real proud of that 1Ds aren't you.
Canon rates the 20D AF sensitivity at a -0.5 EV and it seemed to focus fast enough tonight at a Colt League field hereabouts. I have NO complaint on the AF speed. just the accuracy. at full aperture. and close up.
As a side note the focus point seemed to be a few inches in front of the players at the plate.I guess six to twelve. hard to say accurately from thiry feet away. this works okay when it is pitcher moving into the focus point. As you say at 30 feet the DOF is more accomodating. but the focus point still aint where I locked it.
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 perform 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!
as for the QC problem it may only be one container load or the units from a particular bench. If you knew anything of manufacturing, you might get the idea.
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.
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hmm...
compare the zooms at 50mm...
okay, but why a magic number?
they,the three that I have checked, all front focus at both ends of the zoom range.
:unclesam:
have a good'n!
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Very nice! But this has nothing to do with your current focussing problems, does it! :D
You can download the charts of B&W lines here (http://www.normankoren.com/Tutorials/MTF5.html)
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Hey drh681,
Take heart in that i had exactly the same problem with my 20D with the IS kit lens. It only took me one return to get it right.
You can tell the focus point by shooting a page of newspaper text at 45 degrees with tripod, mirror lock, f9,.... the usual. I can post my tests if necessary, both the first and the second camera.
I feel for you after seeing this post. MANY others have posted similar problems in other forums for the 20D and the EOS1D. However, you will get many replies in the categories of: 1) Here is how my 20D works and it is great (you must be an idiot), or 2) It is a digital feature that only a newbie would be bothered by since you obviously don't use USM (you must be an idiot) 3) You just don't know how to take a photo, hold a camera.... (you must be an idiot).
[ The parenthetical comments are what the repliers are thinking. I think your question is a sensible one. ]
Good luck to you. I love my SECOND 20D. Especially, the IS lens. This is my first really good DSLR, if you don't count the D70 i had for a while. I just wish i could get my closet of Nikon ED lenses to work with it!
Tim
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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"! )
Like I say no offence.
Are Canon charging you for this? I thought they did this sort of thing under warranty.
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here is one of my 'field test' images from before the adjustment by Canon. center AF selected and placed on center box:
(http://www.phototalk.net/photos/data/3175/35frntfcsweb1.jpg)
and here is after the adjustment:
(http://www.phototalk.net/photos/data/3175/3520Dcafter_002.jpg)
and a 100% crop of the after:
(http://www.phototalk.net/photos/data/3175/359973_100cr.jpg)
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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!
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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
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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.
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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
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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.
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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.
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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.
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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.
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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"! )
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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?
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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.
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My 20D has the same problem, maybe just a defective batch, but they will sort it so no problem
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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.
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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.
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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?
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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?
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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.
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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".
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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 :D .
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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.
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I have been having problems with front focusing when the subject is within six feet or so.
the first two cameras were only one s/n apart. this third body is weel off that sequence but still has a front focus of one half to one-and-a half inches in front of the selected focus point.
Am I missing some info about a "design feature"?
After two returns, I agreed with the seller that I would deal with this through Canon if it showed up in the third. So tomorrow is for Canon techhelp; but it really gripes me that I need to send a camera for "adjustments" right out of the box!
I have a 20D and none of these problems, either with the small aperture kit zoom or 200mm & 100mm f2.8 and 50mm f1.4 which would show up problems well. I often use these lens wide open.
Are you using auto or manual focus? Try both.
In auto switch to the centre AF point only so you can be sure what it is focusing on.
I can't believe 3 bodies or all 5 of your lenses are out of calibration, it must be finger trouble (no offence).
Good Luck!
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no offence taken, I understood your reply.
I have noticed that on many boards there is a tendency for the first responders to presume that the poster is "not doing something right".(a fair presumption often enough)
Thanks for that.
By they way I ment to ask if all three bodies serial numbers looked like they were from the same batch?
That would be more in keeping with a quality control isssue.