I haven't owned (or used) 15 different L's, but none of mine have had any problems. It's possible they might be off a little as I've never done anything other some cursory testing, and haven't noticed any problems in real world shooting either. I haven't had any problems with the 50L either, even when I tried to get it to focus shift. That's supposed to happen at 2.0-2.8 at close distances right?

500 4.5, 400 2.8IS, 300 2.8, 300 2.8IS, 70-200 2.8IS, 28-70, 80-200, etc. no problems ever!

moondigger wrote:
But the internet amplification effect is definitely to blame for the general 'feeling' one gets that the problem is rampant and widespread. If it were as prevalent as one is led to believe by the reports here, neither my experience nor the results of this poll would be what they are.

If it WEREN'T all that prevalent, I wouldn't have come across so many copies that required adjustment.



Oh, and as far as the current results:

76 people have had no problems. 45 have had at least one problem.

That's 59% of people that have experienced problems with at least one L lens.

DavidP wrote:
Oh, and as far as the current results:

76 people have had no problems. 45 have had at least one problem.

That's 59% of people that have experienced problems with at least one L lens.


You got that backwards, or I need to wake up

DavidP wrote:
Oh, and as far as the current results:

76 people have had no problems. 45 have had at least one problem.

That's 59% of people that have experienced problems with at least one L lens.

Huh? Is this new math or something?

Current stats:

79 people: no problem
20 people: problem with one lens
24 people: problem with more than one
2 people: problems with every lens

That means ~63% of all respondents have had no problems at all with back- or front-focusing L lenses, and 16% have had trouble with only one. The remaining ~21% have had what might be termed significant issues.

So a significant majority have never had a problem, no matter how many L lenses they've had, and a vast majority (almost 80%) have had only minor problems at worst.

I still want to see if we can get a sample size of around 200.

Jerry

I have/had the 16-35, 17-40, 24-70, 70-200/4, 300/4 (2x).
My second 300/4 had a front-focusing issue - fixed within a week by Canon Irvine.
I now have the 17-55 efs which had the dust problem (so I had to send to Canon for cleaning).
Also, I went though maybe 15 lenses (Ls, non-Ls, third party) till I settle on my current setup. All of these performed exactly as per the independent test reviews on the Internet (e.g. PhotoZone).
So, what are my general conclusions:
- I don't believe in the good/bad copy theory. If bad copies exist, they must be quite rare.
- some of the problems that users report are real. Bad things do happen to good people

All four of my L lenses have problems, the worst is the 24-70, so soft at 24mm at f/2.8.. the sharpest is the 16-35 2.8L II but its got collimation problem on the left and right side of the frame at 16mm. But at least now I know how sharp an L lens can be after purchasing the 16-35 thanks goodness, so it's not the 1d3, it's the lens!!

Is Nikon's focusing system different or something? I've never heard of a Nikon lens back or front focusing, though I know their new bodies do have a correction for it.

Definitely NOT trying to start some flame war here, I am truly curious. I have had a lot of L lenses and have never had a problem, so please don't think I am implying Nikon lenses are superior or anything, I am just wondering if the way they detect focus works differently or something.

I just wonder why if Canon can calibrate them perfectly, often in their first service visit, why can't they just manufacture them correctly in the first place? Weird. Do the get jostled in shipment or some crazy thing? Maybe Canon's boat that they ship them on does not ride as smooth as Nikon's..

Well I don't know about the Nikon AF system, but the Canon isn't a closed loop. The camera AF system determines where it thinks the lens should focus to, tells it to, and the lens moves to that position. This requires either the lens and camera AF to be within tight tolerances during manufacture, or that they can be calibrated. Well its the apparently the latter and one would hope that the manufacture/design tolerances would make back/front focus a rare occurrence, but apparently not.

BTW, it is not only focusing. I got a new factory sealed $5500 500/4L with a factory defect (swath of dirt and dust internal to the lens under the meniscus glass). My next copy was off in calibration.

37% issues is pretty high, and as David said, if the probability is so low, why did I have so many bad-uns.

Gene

GeneO wrote:
BTW, it is not only focusing. I got a new factory sealed $5500 500/4L with a factory defect (swath of dirt and dust internal to the lens under the meniscus glass). My next copy was off in calibration.

37% issues is pretty high, and as David said, if the probability is so low, why did I have so many bad-uns.


Don't feel too bad, my first $1200 Nikon 17-55mm f/2.8 was full of weird metal-looking specs underneath the glass. Apparently it was just some anti-reflective coating that had flaked off, but still. Nikon was VERY cool about it though, and the guy said do not keep it, send it back even though it didn't seem to affect the pictures. Got a new one and it's perfect.

Obviously you have probably deducted from my posts that I have owned and shot both systems. There are great things about both, but I will say that Nikon's AF system is much more accurate from my limited experience with the 5D, 40D, XTi and a D50 and D300. I have not used a 1D so I cannot comment on that, but the D300 obliterates the 40D and 5D (hate to compare them). I don't know how they do it, but it's super accurate.

Now the Nikon lens mount not giving false dead battery warnings is another story. Mine has not done it yet, but I am dreading the day..

Cameras are so high-tech with such tight tolerances that it's not too surprising that they get things wrong sometimes.

moondigger wrote:
Huh? Is this new math or something?



It's Canon math.

Talk about a major brain fart.

moondigger wrote:
The remaining ~21% have had what might be termed significant issues.


Seems like a lot, to me, actually.

Far more than most want to believe.

300mm 2.8 IS & 70-200mm f/4 IS

Canon fixed them both up for free, and now they are gems.

I have a 16-35mm f/2.8 L II, 24-105mm f/4 L and 70-200mm f/2.8 L. All three are spot on and were out of the box.

Hopefully my next (a 35mm f/1.4 L in the next few weeks) will be to.

Come on Canon peers - resond to the poll so we can get a nice sample size.

I've shot a variety of Sigma, Tamron, Canon lenses. My two Ls are 17-40L/4 and 70-200L/4. After a long period of shooting with both, I finally bit the bullet and dropped off the 17-40 for recalibration w/ Canon Mississauga. Looking forward to getting it back soon. I lacked the confidence to say that I had a focus problem with the lense, but doing tests with the 17-40L, the 50 1/4, the 70-200L/4, and an 18-50 Sigma I finally came ot the conclusion that it was not my technique that was the problem.

Now whether the lense was sharp and 'slipped' over time, or if it was always out of whack I can't say.

For such a precision instrument, some limited maintenance I think should be expected. (especially over several years). If you think this is an unreasonable cost, i'd suggest you shouldn't be looking at L glass.

i recently got the 35L, and my copy backfocuses as well.

FWIW

All 8 Ls I have/had focuses correctly.

Bodies can have a bad/front issue as well. However, most of the time lenses are blamed