Mamiya 6 50mm lens "gritty" focus

[punkzter]

This probably applies to any lens, but I've never experienced it before. The focus is kind of gritty. I have the 75mm as well, and it's definitely smooth. It's not awful, but it's not as nice to use (the 50mm isn't as nice, that is).

I contacted precision camera works, and it will be $190 to lubricate the Helical. Or that's their guess without seeing the lens.

My question is, what does it mean when a camera's helical needs new grease. More specifically, if I keep using it, am I damaging the lens? Can I put this off?

Thanks,
Brad

 

[KN4SMF]

It means the threads that make up the focus assembly are all dried up and have sand or something embedded in the grease. The whole thing needs to be taken apart and all the old grease and gunk cleaned out nice and clean, then regreased. If sand or grit is indeed the problem, it will eventually ruin the threads to where focus action will be bad after it is finally cleaned. All this assumes the problem isn't a loose screw inside there, which is much more serious and immediate, and is mistaken for grit.

 

[punkzter]

Okay. that makes perfect sense (though I had hoped otherwise)

 

[MattKing]

It might be that there isn't anything embedded in the grease. The feel may be due to the lack of proper functioning of the grease itself, in which case a cleaning and replacement of the grease would solve your problem.
The concern is that as the grease deteriorates (or migrates away) the helical can experience wear.

 

[punkzter]

Gotcha. Well, in either case, it sounds like a CLA is in order.

I have another question, this time about the 150mm lens. (I'm having back luck with this set of lenses....). I got this one from KEH, and it's probably too late to return it, though I don't think I want to. It focuses smoothly, but at one point in the rotation, it sort of makes a "spring" sound. I don't know how to describe it. I sent it to Precision and they said that there was nothing wrong with the lens. Has anyone ever experience something like this?