KoNickon
Nick Merritt
I had this lens sitting around for years -- never worked. Can't recall when I got it, but the aperture blades were always stuck. I thought I'd give it a go -- found a video that walked me through it. I managed to take it down to the aperture mechanism; removing the optical blocks was very easy once the name ring budged, very reluctantly. Flooding the aperture mechanism freed the aperture blades up. Great!
But in putting it back together I realized the lens had to have been cobbled together and it can't work as configured. The chromed back plate (with the lens mount) has 8 (!) slotted screws that have to be removed (or so I thought) -- four of them are long; four are short. I realized the long screws are to mount the rear assembly that couples the aperture to the camera onto the lens. The short screws are to keep the two plates forming the aperture coupling assembly together.*
So the lens itself has four screw holes for the longer screws, makes sense. They are oriented at top dead center (the focus/aperture index on the lens front), and 3:00, 6:00 and 9:00. The holes on the rear plate for the shorter screws are in between those for the longer screws. This means the rear assembly can only attach to the lens one way. Makes life easy -- except that the back plate on this lens seems to be drilled wrong: The holes for the short screws should be for the long screws, and vice versa. The aperture coupling only works when the rear assembly is positioned so that the short screws are at 12, 3, 6 and 9.
This can't be right, and yet there it is. I could not see how to mount the rear assembly onto the lens based on the screw configuration. Anyone have any thoughts about this? I've buttoned the lens up and put it back in the drawer. At least the aperture works now....
*Before I even got to cleaning the aperture blades I made a bad misstep by unscrewing all the screws. I should have left the short ones alone. As it happened, the rear aperture assembly separated and lots of small parts came out. I was astonished -- 5 miniscule ball bearings, probably 1mm in diameter. And 5 short curved wire pieces. I worked out that they were spacers for the rotating part of the assembly, and the bearings rode in the track between the spacers. (There must have been 6 of the spacers, since there were 5 bearings, but I thought I counted 5. Whatever.) Whether these bearings and spacers were really necessary, I can't say; seems overengineered to me. But at least I didn't lose any of them.
But in putting it back together I realized the lens had to have been cobbled together and it can't work as configured. The chromed back plate (with the lens mount) has 8 (!) slotted screws that have to be removed (or so I thought) -- four of them are long; four are short. I realized the long screws are to mount the rear assembly that couples the aperture to the camera onto the lens. The short screws are to keep the two plates forming the aperture coupling assembly together.*
So the lens itself has four screw holes for the longer screws, makes sense. They are oriented at top dead center (the focus/aperture index on the lens front), and 3:00, 6:00 and 9:00. The holes on the rear plate for the shorter screws are in between those for the longer screws. This means the rear assembly can only attach to the lens one way. Makes life easy -- except that the back plate on this lens seems to be drilled wrong: The holes for the short screws should be for the long screws, and vice versa. The aperture coupling only works when the rear assembly is positioned so that the short screws are at 12, 3, 6 and 9.
This can't be right, and yet there it is. I could not see how to mount the rear assembly onto the lens based on the screw configuration. Anyone have any thoughts about this? I've buttoned the lens up and put it back in the drawer. At least the aperture works now....
*Before I even got to cleaning the aperture blades I made a bad misstep by unscrewing all the screws. I should have left the short ones alone. As it happened, the rear aperture assembly separated and lots of small parts came out. I was astonished -- 5 miniscule ball bearings, probably 1mm in diameter. And 5 short curved wire pieces. I worked out that they were spacers for the rotating part of the assembly, and the bearings rode in the track between the spacers. (There must have been 6 of the spacers, since there were 5 bearings, but I thought I counted 5. Whatever.) Whether these bearings and spacers were really necessary, I can't say; seems overengineered to me. But at least I didn't lose any of them.
AlwaysOnAuto
Well-known
I cleaned my two lenses up and vaguely remember what you're talking about, sorry it's been a while since I did it. If I can figure it out I'm sure you can too. I'll have to check to see if I took any pictures when doing it. Can't remember off the top of my head. Must be getting old or something.
AlwaysOnAuto
Well-known
I remember now. This is the assembly you're struggling with. When I watched the video (not sure if it was the same one you did or not) I made sure to not take it apart for the reasons you're citing here. I remember removing one screw to see how long it was, then the one next to it to see which was which. Sorry I don't have any other pictures, hope this might be able to help you. That ball bearing is one of the smallest I've ever seen and as an ex-machinist I'm amazed at how they can even be made. The spring is pretty small too.
KoNickon
Nick Merritt
Yup, that's it. I must have watched the wrong video since the lens being worked on there was probably a somewhat later version -- not as many screws in the back (and no warning about removing the short screws). But after reassembling it I think the lens had the same flaw as when I first took it apart -- in other words, I don't think I reassembled it incorrectly. Namely, the post protruding from the rear plate, as shown in your picture, is supposed to push against another post attached to the actual aperture assembly, which acts to open up the aperture. But as assembled, the rear plate post doesn't push far enough to strike the aperture assembly post. I tried all sorts of things but the fact the holes in the rear plate are specific to either the long or short screws means the rear plate attaches only one way.
And yeah, those bearings are really tiny. Remarkable.
And yeah, those bearings are really tiny. Remarkable.
AlwaysOnAuto
Well-known
I remember having a similar problem when reassembling my lens. It's a matter of getting the clocking of all the parts correct so the posts interact with each other correctly. Might take some trial and error work to get the correct orientation between the pieces. In cases like this I sometimes work backwards ie figure out how to get the posts to work first, then work on the orientation so the screws will work.
KoNickon
Nick Merritt
Yeah, I hear you, and thanks for that. I haven't given up yet, but I'm kind of feeling I tried all that, and the only way the linkages worked was in an orientation where the long screws couldn't thread through to the back of the lens.
p.giannakis
Pan Giannakis
Have a look here
Attachments
p.giannakis
Pan Giannakis
This is even better.
KoNickon
Nick Merritt
Thanks for these! Neither of these really describe the issue I'm having with reassembly, though. But I will have at it again.
p.giannakis
Pan Giannakis
Those three screws are the difference between an easy lens to service and a 3D jigsaw nightmare. Keep us posted, there is not a lot of information out there about the issue you are experiencing.
KoNickon
Nick Merritt
I was thinking of 3D chess but your metaphor is better! I was pondering it during a walk this morning and I just can't figure it out. I will have to open the whole thing up again because I continue to think that the holes on the back plate are reversed -- long screw holes should be where the short screw holes are, and vice versa. <shaking my head in frustration>
AlwaysOnAuto
Well-known
Sounds to me like something is flipped around the wrong way.
KoNickon
Nick Merritt
Possibly. But generally speaking these things go together only one way. That's what I'm trying to figure out.
p.giannakis
Pan Giannakis
AlwaysOnAuto
Well-known
I seem to remember when I tried to assemble that assembly I pictured back into the lens, the posts that had to interact with each other didn't, so the aperture wouldn't activate. Took me a fair while to figure out the orientation of all the pieces so they would.
If I were in your shoes, I'd take it apart so that all the 'rings' are naked and get their orientation correct first, without all the other parts causing problems. Then I'd keep them oriented and carefully start to add pieces to the puzzle.
It's tedious at times, but for me my motivation was the fact I once took a perfectly good Leica Summitar apart and couldn't get it back together. I foolishly gave that lens up in trade for labor on another lens.
If I were in your shoes, I'd take it apart so that all the 'rings' are naked and get their orientation correct first, without all the other parts causing problems. Then I'd keep them oriented and carefully start to add pieces to the puzzle.
It's tedious at times, but for me my motivation was the fact I once took a perfectly good Leica Summitar apart and couldn't get it back together. I foolishly gave that lens up in trade for labor on another lens.
AlwaysOnAuto
Well-known
This is true, and works in your favor since there are only so many combinations of assembly you'll need to try to find it.
AlwaysOnAuto
Well-known
This kind of reminds me of the first time I changed the oil on my old '68 BMW 1600. The filter I'd bought, a spin on, was too big in diameter for the mount location.
My dad told me 'It was designed by a guy who puts his pants on the same way you do, one leg at a time. You'll figure it out.'
I did and drove that car for 9 years after that.
These were designed to be made on an assembly line. It can't be that hard. It's not rocket science.
My dad told me 'It was designed by a guy who puts his pants on the same way you do, one leg at a time. You'll figure it out.'
I did and drove that car for 9 years after that.
These were designed to be made on an assembly line. It can't be that hard. It's not rocket science.
AlwaysOnAuto
Well-known
The key to this assembly is rotating the rings, relative to each other so that the post orientation is correct based on the screw locations.
KoNickon
Nick Merritt
Yup. The thing is, the four long screws are 90 degrees apart from each other, and the four short screws in between are also 90 degrees apart from each other. The long screws on the rear plate (the rear of the lens, with the lens mount) have to go at 12:00, 3:00, 6:00 and 9:00 in order to reattach the assembly to the back of the lens (i.e. the portion forward of the aperture ring). It seems that the correct orientation of the assemblies needs to be shifted 45 degrees in order for the aperture mechanism to work -- but you can only reorient it by 90 degrees since the holes for the short and long screws are not interchangeable. In other words, the aperture linkages work right for me when the rear assembly has the short screws in the 12, 3, 6 and 9 locations -- which of course isn't correct since it won't attach to the rest of the lens.
p.giannakis
Pan Giannakis
Did you disassemble the whole aperture housing? If you removed the aperture blades to clean them, there is a specific way they need to be adjusted to reach the correct f/16 position. I wonder if that is why the levers don't align.
Look at this video - it is for the 55/1.7 but it is similar. Go to 20:40 and see how he describes it
Look at this video - it is for the 55/1.7 but it is similar. Go to 20:40 and see how he describes it