I wanted to try out this oddity of a lens. I shoot a lot of wildlife, so a long focal length lens is handy. Even handier is a physically short and lightweight lens. I snagged this lens for a bit less than normal because there was obvious dust/stuff inside.
I first thought of just removing the front element by unscrewing the ring … but it would not budge. I checked the web, and others show a disassembly … Ok, doesn’t look that hard.
Tools – philiips screwdriver, cleaning stuff, and painters tape
First thing to do is get the tape out, set the lens to infinity focus and place a tape reference on the outside between outer focus ring and body.
TIP: try not to rotate anything during disassembly.
Next you need to take off the PCB board with the contacts. There are two screw holding it on and there is a spring underneath one side.
Next remove the screws from the mounting ring.
Pull off the mounting ring a bid and then maneuver the PCB through the hole to separate them.
The outer body is held on by the four screws.
Note that the PCB and chip are attached to this part, so try not to damage it … and it sits in a slotted area.
At this point you might want to get the tape out again and make more reference marks on any rotatable parts.
In order to remove this rotating focus collar you will need to remove some gears … make a tape reference to its position.
Two screws hold the gears on.
Try not to lose any parts when you remove it … and also try to keep the lube.
Pull off the column.
Then just unscrew the two parts.
Clean up, and try not to scratch the mirrors.
Those tape marks will come in handy to make sure you correctly get the correct position of the front group on the focus helix.