17-85 problem

[fmueller]

<p>This morning I started getting Error 99 on my 20D with the EFs 17-85. The same lens gives Error 1 on my T1i. Both cameras work fine with other lenses. So it seems my trusty 17-85 is the culprit. I've cleaned the contacts with an eraser to no avail. The most common problem with this lens seems to be a broken shutter flex cable. Does this sound like what I am dealing with?</p>

<p>As it happens, I ordered such a cable several years ago so I would have it on hand when needed. Of course now I am in the process of moving, and this cable is probably at the bottom of a huge mountain of moving boxes, and I'd probably rather order a new one than try and find this sucker.</p>

[ed_avis2]

<p>You could try attaching the lens, setting the camera to f/16 aperture priority, and pressing the depth of field preview button. This should cause the lens aperture to close - if not, I guess you may be right that some cable to the aperture diaphragm is broken.</p>

[fmueller]

<p>Ed - thanks for the suggestion. I did it on my 20D. Behavior is erratic. Sometimes the lens stops down, sometimes not at all, sometimes it seems to stop down a little but not all the way to f16. After trying about 20 times, I got Error 99.<br>

<br />This seems to confirm that there is a communication problem, but how does this help me distinguish if it's in the camera/lens interface, or in the lens itself?</p>

[ed_avis2]

<p>I guess if you've cleaned the contacts and you don't see the problem with other lenses, then the lens must be at fault. That doesn't tell you whether the diaphragm is physically broken or just a wire has come loose. Tho' the fact that it is erratic suggests a mechanical problem perhaps?</p>

[fmueller]

<p>Or a loose connection? I've ordered another one of these flex cables. They are cheap, and it should be here in a couple of days. Once it's here, I'll open the lens and swap it out, keeping an eye open for other issues. If that doesn't fix it, maybe it's time for a 15-85 ;-)</p>

[Marcus Ian]

 

<blockquote>

<p>This seems to confirm that there is a communication problem, but how does this help me distinguish if it's in the camera/lens interface, or in the lens itself?</p>

</blockquote>

<p>It's in the lens itself. The erratic nature suggests (to me) an incomplete break on one of the traces in the flex cable - or a crack in the cable in which the broken trace ends are contacting each other at certain points/positions (perhaps nearly all?). I might suggest trying to zoom (back and forth) the lens and see if there is any consistency in the times when it throws a 99, though that might take a while. I think your solution is the likely fix.</p>

[fmueller]

<blockquote>

<p>The erratic nature suggests (to me) an incomplete break on one of the traces in the flex cable.</p>

</blockquote>

<p>That was my thinking exactly, plus the cable breaking is a known weak spot of the 17-85. Rather than waste any more time with it now, I think I'll just wait for the new cable to arrive and swap it out.</p>

<p>I can not believe I have a new cable in the garage, but unreachable in one of a gazillion boxes! I felt so smart when I ordered that cable some years ago. Oh well, the fun of moving!</p>