Bronica "S" 100mm f2.8 disassembly

[OAPOli]

Bought one of those on eBay, with some haze. These lenses don't come apart the usual way. Fortunately I found a guide in Japanese (link) for the 7.5cm Nikkor-P and the 100mm is very similar.

Required tools: flat blade screwdrivers, spanner and tweezers.

First measure the extension of the barrel. Of course I didn't know the first time.

Unscrew the retaining ring, remove the aperture actuator, and loosen the three set screws.

The lens mount barrel slides off, watch out for the ball and spring.

There is a spacer. Unscrew the aperture preset follower.

Screw in the barrel a little bit until the 3 holes line up with the 3 set screws. This is where the first measurement comes handy. You might miss the set screws and lose track of the correct position. Too far in and there will be a gap between the index dot and the engravings, too far out and the aperture ring will bind.

Loosen the set screws and you can unscrew the front group. If you need to go between the elements, the name plate/filter ring is attached with more set screws. To access the rear group I believe one needs a custom tool: not enough room for generic spanners.

 

[ic-racer]

Nice thread!

 

[reddesert]

Thanks for that. I have looked at a Bronica Nikkor 75/2.8 several times without figuring out how to get in, so that tumblr post and your remarks will be very helpful.

 

[choiliefan]

Thanks for posting this.
I have a minty 135 which needs to be disassembled, cleaned and lubed.
Tried to work on it once but didn't get too far.

 

[OAPOli]

Just a little addendum about reassembly. The FFD is defined by the silver spacer shown in pic no.5. So one should slip on the barrel (you need to push the ball bearing a bit), secure the lockring, then tighten the three setscrews.