New 100-400L, seagulls, and good Canadian price.

Ecoh wrote:

I have used this lens almost every day for about 8 years.. I use it mainly for birding so I have packed this lens on hikes through marshes, beaches, and woods. It is my favorite lens, for being versatile and light enough to carry around ready to shoot all day.

I have never had a problem with dust in it, or with the push pull mechanism getting hard to slide. There is some black material under the ring that locks the lens that seems to degrade after a few years of use. I had this replaced 4 years ago and just recently again. I just send it to Canon for a cleaning and focus check and they replace that material at no charge.

You will really enjoy this lens.

Ahah!

Glad to hear someone whose experience proves the point.  For one who also noticed the "black material" and thought it was a simple "cleaning job":  There is no black material under the lock to degrade.  Take it from one who has had very expensive experience.  That black material is one or more displaced bearings under the zoom lock.  They jam and are driven up and down as the lens moves leaving fine black mark traces that look for all the world like "dirt marks" especially as they can be wiped off. The effect is a sort of slight resistence when moving the slide which once overcome slides normally.  It is just slightly unpleasant and not the usual butter-smooth original action.  It was a desire to do a simple clean that led me to my mistake.  If the screws attaching the zoom lock are removed the zoom easily comes apart and  immediately disgorges hundreds (thousands?) of microscopic bearings virually all over the table and your lap.  The design of the zoom lock entails two tracks of opposed bearings in an usealed race (bearings on the opposing outsides).  Someone else suggested that they must be assembled using magnets as there could be no other way to do this.  I found a lens construction diagram somewhere on the web before I tried to clean the barrel but it was not explicit on how the race was made.  I can generally fix lenses and I am not casual about it.

The fact that Canon clean and focus check with no charge for materials more proves my point that they are aware of the problem and repair it quietly at no cost rather than publicly acknowledge the problem.  In my case I foolishly tried to clean the lens myself  - my problem and I paid the price - sorry to have bothered explaining.  But my very problem showed me the construction details, the propensity for tiny ball bearings to be jolted out of open races is quite real.  It was only a thorough search of the web at the time that identified from other experiences that it was the jolted-out bearings that caused the problem and that in some cases the roaming bearings got inside the lens and wrecked the IS mechanism.

Having said this I acknowledge that this is a great lens, it is very useful, can stand up to normal use, gives people a huge amount of pleasure, etc.  No need to be a killjoy.  People can use this lens for years or for a lifetime with no problems whatsoever.

However the "trombone action" with no soft stop at lens and two opposed open race bearing tracks containing microscopic bearings is bad design.  Problems are bound to happen on occasion, but surely they are not inevitable. I just merely caution not to be over heavy on hitting the end stops and there is no meter that can show how much is ok and what is too much.  A factory inserted soft stop at either end should have cured the problem but as far as I know the design is quite old and has never been changed.  Canon must simply re-pack the bearings with a special tool whenever the lens is send in for cleaning "the degraded black material" from under the lock ring.

One might have thought a surrounding ring with a nylon sliding ramp would serve as a lock - the highly complex and resulting potential for failure seems an engineering overkill for such a simple function.