Keith Green wrote: > Hi All, > While I was carrying my EOS3 with a 300 f4 IS and 2x converter > mounted this morning, I heard the IS working. The camera was also > metering. > I half-pressed the shutter release, then released it and everything > shut down.
Hi, Keith, this seems to be a problem familiar to 300/4 L IS USM users. I have one and have seen the same thing occur on my EOS 50 *and* my D60. It never happens with my 80-200/2.8 L. Here is what I wrote in October 2001, containing somewhat more details which may be (or become) interesting in your pursuing the issue: <quoting me> since I have the 300/4 L IS USM lens for my EOS 50, a problem occurred every now and then: As soon as the trigger was pressed lightly to activate AF and IS, the camera would all of a sudden fall into a state as if no (or an unrecognized) lens was mounted. The stop would read as "00" and the "MF" symbol would flash. There would be a short "clack" sound of the IS and/or AF which would both be "dead" afterwards. A few seconds later, the stop would read correctly again and the camera would work perfectly for a large number of shots again (until today) or very likely show the same behavior (since today). If the trigger was pressed after this has happened, the mirror would swing but the film would not be transported nor exposed, i. e. the shutter would not open. It would then be needed to switch the camera off in order to release the mirror, after which it would be operational again. This usually happened about every 30 shots and could be dealt with - until today, when all of a sudden things got worse and the problem occured almost every single shot. I found out this could be worked around by unlocking the lens, turning it some degrees, turning it back into locked position and activating AF and IS immediately (i. e. within a second) by lightly pressing the trigger. But this cannot possibly be a forever solution! The unit will continue working as long as the trigger remains pressed lightly (i. e. AF/IS remain activated) but as soon as the button is released and AF/IS deactivated, things start all over again. The problem occurs inrespective of IS or AF being switched on or off. It even seems to get worse with both off. There are two guesses of mine as to the reason of this problem: 1. Contact problems - this would explain why things will work immediately after turning the lens forth and back into locked position. It would, however, not explain why the camera will work if the trigger is pressed *immediately* but won't work if done so a second later. 2. Voltage/load problems - my presumption is that this lens, especially starting IS and AF is some nice energy sink which may pose too much of a load on the 2CR5 battery. This would explain the "immediate/1 second later" behaviour of the workaround described. It would, however, not explain why things get worse with AF/IS off. I am thinking of testing the combo with the battery pack instead of the 2CR5 battery (should be more stable under load). I am not even sure if the problem is with the lens or the body, though the lens is more of a suspect because the camera works perfectly with the 80-200/2.8L. All the contacts have been cleaned repeatedly, to no avail. Anyone in here able to provide some help? Is this a known issue, maybe even known to Canon itself? <unquote> From my knowledge of today I should add the following: Unlocking and turning back and forth of the lens seems the safest method of getting the combo back to operation. Switching the camera off and on doesn't always work, neither does waiting until the AF/IS deactivates again. I have, however, never again experienced the problem to be as bad as when I wrote the quoted part; my "normal" workflow, if it occurs every 50 shots or so with my EOS 50 or D60, is to unlock/relock the lens as described which will render the camera operational again. In my following attempts to find the culprit and a remedy, voltage problems became more and more unlikely because even using a laboratory DC power supply didn't help out. My "cure", accidentally found, was rotating all control knobs available on the EOS 50 several times, after which the combo would suddenly work fine again (the problem still occurred but only, say, every 50 shots or so). It doesn't occur more often on the D60 I currently use, so I haven't experienced it to be a major PITA with this camera body. Nonetheless I still haven't found a convincing explanation for the issue and I haven't heard of Canon offering one or even recognizing that there *is* in fact an issue. So long - Ralf -- http://schmode.net (animal photography) * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
