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|| News Item: Posted 1999-08-30

Canon EOS-1n Maintenance Tips
By Charley Provance, Horizon Electronics

(Charley Provance operates Horizon Electronics, an authorized Nikon and Canon repair center in Union City, CA in the San Francisco Bay Area. Charley offers the following maintenance tips for your EOS-1n or EOS-3. By reading some of these tips you can avoid the embarrassment of having some of your important pictures turn out REALLY soft, like what happened to me a few years back - Brad Mangin.)

Photo by
1. The life expectancy of the EOS1N shutter unit is around 100,000 frames. The camera stores a count each time the camera shutter is released. This information can be read only by using the Canon software and the hot shoe interface device used by repair shops. We can usually provide this information to our customers while they wait. For information purposes, we record the frame number on each repair.

2. On most of the lenses used by professional photographers, the lens mount takes the most wear and tear. The lens locking pin hole on the mount can become deformed and cause miscommunication with the camera. The lens contact fails to connect correctly with the contact pins on the camera body. This can cause the camera to not fire during an important play.

3. Another item to look for is the lens mount stopper pin. If the stopper pin breaks off, the lens mount turns too far when mounted on the camera and shears off the lens interlock pin on the camera. Then the lens will not focus or respond at all. The camera doesn't know a lens is mounted if the lens interlock pin is broken.

4. Many times the manual focus ring doesn't respond correctly. It may go in the opposite direction too. This is usually the result of dirty manual focus brushes. They are located inside the lens barrel and is a micro-fine brush that sends a reference signal to the ultra sonic motor (USM). They get dirty and send a mis-signal to the USM. Now your manual focus goes south. Normal auto focus will still be fine, but you can't get that little "tweak" of focus to work with the manual focus ring.

5. If soft focus occurs on one body and not on another, perhaps the body depth is off. Camera body depth is the distance from the front mount ring to the pressures plate. We use a gauge block and a depth micrometer to measure the body depth. The tolerance is plus or minus .03mm. That is the thickness of a strand of very thin hair. The body can be distorted with the use of long and heavy lenses, or if the camera and lens were dropped. The check for body depth is simple and requires only a few minutes to determine
if the measurement is off. To correct the problem usually involves repair and sometimes replacement of major body parts, like mirror box or main body casting.

(Charley Provance can be reached at Horizon Electronics in the San Francisco Bay Area via e-mail at or by his toll-free phone number (800) 233-6169. Check out his website:

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