I need to remove front lens component to clean above lens. Anyone know of a toolkit (spanner, etc), and/or repair guide/manual for this lens?? Thanks, Dave P

-- david l. phillips (dlphil@cox-internet.com), November 04, 2001

Answers

Following are a few things that an ex-camera repairman taught me. He recomended gasoline or alternately isopropanol as a lubricating solvent.

You will need jeweller's screwdrivers, a spanner, a rubber sheet and cup to remove the front shield as well as a clean place to work. Fargo enterprises sells most of the tools needed but I'm sure there are other places.

Look for volumes 1 & 2 of Tomosy's books "Camera Repair" for some general guidelines. I don't recall anything specifically on Canon lenses but you should get the general idea.

The plastic front ring (bezel) is removed first. This has the Canon logo and the lens description. Put a drop or two of gasoline along the outer edge of the ring where it meets the barrel of the lens. This loosens and lubricates the ring and allows the ring to turn. To turn the ring, find a cup with a diameter about the same size as the ring (~50-52 mm), put a rubber sheet over it to protect the lens and increase friction then place it against the ring and turn counter- clockwise. I used a rubber surgical glove. The ring usually turns out nicely.

Once the ring is out I recall that there are a number of thin threaded metal rings with indentations holding the lens elements in place. These can be removed with the spanner. If the rings are stubborn try a drop of gasoline along the mating edges.

I use a mixture of half & half household ammonia and hydrogen peroxide to clean the glass and then shake it off and let it dry on edge.

When reassembling the lens use a quick blast of dry air between the lens elements just before you put them in place. This pushes out any loose dust and prevents more from coming in.

It's fairly easy but tedious to CLA the diaphragm. I've forgotten some of the steps but they're quite obvious once you get the front elements out of the way. OTOH, getting the helicoid to start and mesh properly is much more difficult so I don't recomend it.

Good luck and cheers,

Duane

-- Duane K (dkucheran@creo.com), November 05, 2001.