Nidelva river through Trondheim Norway

Nidelva river through Trondheim Norway
by Saaru Lindestokke                

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The focus of Canon 200mm f/1.8 L seems to be entirely USM driven. Manually rotating the black ring has no impact at all on mine, as it is broken.

What tool set would be the best I could buy (from Amazon for instance, or any other online shop) to unmount the lens until I get to the failing USM part ?

Also, where can spare parts of such a rare lens be bought from?

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While i appreciate the desire to fix it yourself, have you any experience with fixing lenses/are you familiar with lens construction? Do you have access to a clean room? Why not get canon to repair it themselves (at least they wont damage the lens in other ways as you might)... – NULLZ Jul 25 '13 at 8:49
That will be a challenge, indeed, but I am willing to take the risk. You are 100% right regarding the clean room. I know a place I own where there is very little dust in the air, and no air movement at all. I'll just have to make sure I get the right gloves and ad hoc cleaning tissues that will not put any mark on the lenses. – Skippy Fastol Jul 25 '13 at 8:55
@D3C4FF you don't need a clean room - a lens that old will probably have dust inside it already! Canon wont fix it (though they'll happily sell you a brand spanking new 200 f/2.0L IS for $4000) and the lens is useless without an AF motor so you might as well have a bash at fixing it. – Matt Grum Jul 25 '13 at 9:39
@MattGrum: No there is nearly no dust inside :-) I bought it for only 1500$... And the lens is not completely useless. It focuses at a fixed distance of about 8 meters right now :). Fixed focal distance, fixed focus distance !!! :) – Skippy Fastol Jul 25 '13 at 9:55
@SkippyFastol Just a shot in the dark, but you are aware the focus-by-wire isn't active unless the shutter is half pressed aren't you? Also, check to be sure the "Focus Preset" slider isn't pushed towards the direction of the camera body. If it is and the knurled reading ring just behind the rubber focus ring is stuck anywhere but centered (either right or left will lock focus), the lens will lock in the focus distance it is set to when the camera is powered on. – Michael Clark Jul 25 '13 at 15:34
up vote 5 down vote accepted

The 200 f/1.8L is indeed focus-by-wire only.

Taking apart the lens is not a problem, but finding replacement parts is - they're no longer available from Canon and the Canon service centres are unlikely to have any in stock. I looked at buying a 200 f/1.8L with a broken AF system, the seller had found someone selling the replacement USM unit but even then I decided it too big a risk, if the fix didn't work the lens is next to useless as there's no way to focus it.

I suggest you trawl ebay for replacement USM units or donor lenses, contact the larger lens service centres to see if they have any inventory.

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"Focus-by-wire"... I see. I will follow your advice and post my question is forums etc. The first things I will have to do is diagnose very precisely what is going wrong with the lens. Thanks for your feedback. – Skippy Fastol Jul 25 '13 at 9:33

Check out the tools suppliers for profesional jewelers and mobile phone repairers. These tools will be your best bet except for any custom tooling that you will need to either purchace from a specialist supplier or improvise.

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Sublime. Thank you so much ! – Skippy Fastol Sep 22 '13 at 22:52

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