Screws on the mount this time. Looks simple. Looks, however, can be deceiving. That rear element could use a good cleaning.
That is a dirty filter. This is one good argument for putting filters in front of lenses. I usually don't, unless I'm going somewhere really dirty like the beach. This one has managed to keep the front element fairly clean, though.
The front element under that filter needs a good, gentle scrubbing.
The mount came off easily. I needed to focus the lens at its limit in order to free the aperture linkage though. There is a little stop for the aperture ring, but the ring comes off with it in place.
Aperture ring removed and ready for cleaning. I pulled off the long screw at 5 o'clock on the lens in this picture. It is the link between the ring and the aperture mechanism. Finally I removed the aperture index stop which is held on with two small slotted screws.
The index ring is interesting on this lens. It looks like two separate pieces but it isn't. I'd love to know how they chromed part and painted part and still got the quality of finish that they did. This is a JIS screw (Japanese Industrial Standard). As I pointed out in the last blog entry while they look like Phillips heads, they aren't. Phillips screw heads and screwdrivers have an angled slot which is designed to prevent over-torquing the fastener. JIS slots have parallel sides and a Phillips will actually cam out of the screw, ruining it quickly. You've been warned.
The index ring removed. This is where things get complicated. I've removed the mount, I've pulled off the aperture ring and the index ring. I spent the next hour or so trying to figure out how to open up the lens further. I knew that the lens had to open somehow, yet I couldn't figure it out. On some lenses the logo ring unscrews opening from the front. Not on this one. Also sometimes the rear element ring can unscrew, allowing access from the back. Nope, not this one.
Finally, I spot it. A tiny grub screw in the focus ring. I unscrew it carefully with one of my tiny jeweler's screwdrivers. It serves no obvious purpose. I turn the lens over and over in my hands, twisting and pulling and pushing on parts. Finally, I grab the rubber jar opener and twist on the focus ring, figuring that screw must do something. I feel it give. The front angled portion is separate!!! It unscrews from the front of the focus ring, revealing the structure beneath.
Hiding beneath that angled part is another ring fastened with another grub screw.
Removing it allows the entire lens body to be pulled out of the focus ring/lens mount unit.
The lens body out of the mechanism portion. Lots of oil on the outside explains the oily aperture.
Because this lens uses a kind of construction which Nikon calls "close range correction" the rear elements are in their own module which rides on its own helical which moves at a different rate from the main lens body when the focus ring is rotated. This means that the front and rear element packages are a different distances from the focal plane as the focal distance changes.
For my purposes that means that the rear element package unthreads from the main module, revealing the aperture blades. I first marked the location of the package on the main body so that I would be able to replace it in the correct index. The threaded section is actually four complete helicoids so it is possible to put it together three incorrect ways and one right way.
The aperture blades sit VERY close to the rear element of the front module. The grease them was thick enough that it had made little grease pathways on the glass. I used cotton swabs and paper towel strips soaked in lighter fluid to gradually get the grease off the glass and off of the aperture blades. This took a while but eventually the were clean, dry and snappy.
The main body was just a little grimy, so it got a good scrubbing with vinegar. The focus action was still smooth so I didn't need to pull it all apart and regrease like I did the 105 f2.5. This cut a couple of hours off the time required to service this lens.
Reassembly. This is the out angled section threading back on. Also, note the tiny hole near the front of the focus ring. That is the hold for the grub screw. There was enough dirt packed on top of it that it was really hard to see.
The aperture click stop mechanism being replaced.
All back together.
Nice clean front element and filter.
The rear element cleaned. Nice shiny mount, too.
While I was at it, I cleaned the dirt off the Halliburton case with a Brillo pad and Windex. This was really dirty, having lived in a garage for the last 20 years or so and probably hasn't been cleaned ever.
Top is clean, bottom is not (duh).
Re-loaded, ready to give back. I now want to see film put through this beautiful system.