kevin m
Veteran
I've owned about half a dozen VC lenses, I'd guess, and every one of them has had a sticky focus throw. I bought a second copy of the Nokton 40/1.4 because I liked the lens so much, but even after sending it to DAG to be relubricated, it never did loosen up to my liking, no matter how much I used it.
The funny thing is, I can't remember a single lens from another manufacturer that I've had this trouble with. Leica, Konica, Canon LTM, they've all been fine. To me, the VC's feel like they're lubed with glue - way too much resistance! Has anyone had any luck relubing the lenses and getting a light, easy focus throw? I'm fairly handy so I'd consider doing it myself. I'm looking at the micro tools catalog and thinking about taking my 35/2.5 apart.
The funny thing is, I can't remember a single lens from another manufacturer that I've had this trouble with. Leica, Konica, Canon LTM, they've all been fine. To me, the VC's feel like they're lubed with glue - way too much resistance! Has anyone had any luck relubing the lenses and getting a light, easy focus throw? I'm fairly handy so I'd consider doing it myself. I'm looking at the micro tools catalog and thinking about taking my 35/2.5 apart.
kevin m
Veteran
Nobody's been tempted to try it?
Beemermark
Veteran
I doubt that's it a matter of lubrication. The synthetic grease used today lasts decades or more and shouldn't wear out, if any is even used. The tightness is due to the materials selected and tolerances. While the optics of the CV lenses are good the build quality is not in the same ballpark as Leitz lenses. If your adventurous try some taking the lens apart, use some valve grinding compound on the threads, run it back and fortha few hundred times, then clean it and re-grease it.
Livesteamer
Well-known
I've only got one CV lens, a 75mm f2.5 and it's smooth as silk. I would be very hesitant to use valve grinding compound to loosen up a focusing helicoid. These threads need to be very precise. If they become the slightest bit loose and sloppy your focusing accuracy will be seriously degraded. Joe
Ronald M
Veteran
At one time Leica lenses were laped in, then cleaned and lubed.
I am sure this is one step CV thinks they can skip. How do you suppose they make them for 1/10 the cost?
I am sure this is one step CV thinks they can skip. How do you suppose they make them for 1/10 the cost?
Al Kaplan
Veteran
My 15mm developed a "tight spot" almost immediately after purchasing it used a few years ago. Since I rarely focus it at anything other than at one meter because of the great depth of field I haven't really been concerned about it. I did dribble a little penetrating oil into the focussing helicoid, being careful not toget it where it could sneak inside the lens through the diaphragm mechanism. After working the focus back and forth several times it did loosen up and focus more smoothly.
The next day it was right back where we started. Move it back and forth a few times and it loosened up again.
First off, aluminum against aluminum doesn't make for smooth focussing. Aluminum against brass is much better, but brass is expensive to machine. Brass against brass is even better still. To some extent brass is self lubricating. It's possible that the VC lenses might even have molded helicals, not machined at all.
Second, whatever lubricant they use tends set up and wants to resist moving.
Third, the aluminum focussing ring is very thin and distorts under finger pressure. Using my thumb and two fingers spread evenly around the lens at three points, and not squeezing the ring, and the lens focusses much easier than grabbing it just between thumb and index finger.
I don't think that there's much hope for getting Leica smoothness out of the focussing mounts on the VC lenses. They're a great value, good optics, but the price savings had to come from someplace. The mounts took the hit.
The next day it was right back where we started. Move it back and forth a few times and it loosened up again.
First off, aluminum against aluminum doesn't make for smooth focussing. Aluminum against brass is much better, but brass is expensive to machine. Brass against brass is even better still. To some extent brass is self lubricating. It's possible that the VC lenses might even have molded helicals, not machined at all.
Second, whatever lubricant they use tends set up and wants to resist moving.
Third, the aluminum focussing ring is very thin and distorts under finger pressure. Using my thumb and two fingers spread evenly around the lens at three points, and not squeezing the ring, and the lens focusses much easier than grabbing it just between thumb and index finger.
I don't think that there's much hope for getting Leica smoothness out of the focussing mounts on the VC lenses. They're a great value, good optics, but the price savings had to come from someplace. The mounts took the hit.
shimo-kitasnap
everything is temporary..
Of all the CV lenses I've owned, the only one that was really stiff was the 35f2.5 pII. I've since sold it and use a summicron-c, which is kinda stiff but DAG says he can lube it back up to run like butter. I used to have a 40 rokkor m from a minolta CL which runs smoother than my summicron-c, but I think that's just an age issue.
kevin m
Veteran
Thanks for the tips, guys. I might try some valve lapping compound.
It is a shame because the optics are, in some cases, first rate and unique. Heck, even my Minolta Rokkor 40 was smooth as butter, why can't VC do the same? It's not as if the lenses are cheap, they're only cheap compared to Leica.
It is a shame because the optics are, in some cases, first rate and unique. Heck, even my Minolta Rokkor 40 was smooth as butter, why can't VC do the same? It's not as if the lenses are cheap, they're only cheap compared to Leica.
Beemermark
Veteran
Good luck and let us know how it goes. Get the finest lapping compound you can. It won't hurt anything. As an aside, a company exists that sells bullets impregnated with a lapping compound. You load your own and fire about 10 rounds going from a coarse compound to degrees of finer compound. The purpose is to smooth out those microscopic imperfections in the rifle barrel to improve accuracy.
Larry H-L
Well-known
Two of my new C/V lenses were stiff to focus. With very small drops on the end of a toothpick, I carefully put some plain "3 in 1" oil on the exterior focus helicoids and worked it back and forth. I repeated this a few times, and now they are silky smooth, and have stayed that way for several years.