Lens Focus Snagging

[skinnfell]

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My 28/2 is in great condition and sees regular use. However, every once in a while the focusing ring "locks up" or snags. As if there is something inside the lens which stops the focusing path. With a little "massage" it loosens up again and is back to normal. This usuallly happens when the lens has been sitting in the bag for a bit. I suspect insufficient lubing, but is super smooth and precise on all other occasions. It does not feel "dry" in the focusing, and really is not old enough to experience this IMO.

 

My question:

Does anybody recognize these symptoms with this or other lenses?

 

In such case, did you ever find out what caused it?

 

I would rather not send such a new lens to full CLA, expensive too.

(Unfortunately out of warranty...)

[Washington]

Gee, I really don't know for sure. But, the first thing I'd try is just a wee bit, and I do mean a

wee bit of good oil under the outer ring...... turn it back and forth a few times and let it settle

for awhile. Good luck, cheers, Rip

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[250swb]

I wouldn't put oil anywhere near it just yet.

 

The symptoms are similar to the mounting flange being off centre, something that seems to happen from time to time. As lenses are mounted and dismounted the flange takes a good deal of rotational force and this can cause the flange to go off centre even though the screws seem tight. Rotating the focus back and forth re-centres the flange until next time, or sometimes it can become set and stay snaggy.

 

The solution is to loosen all the mounting screws and gradually retighten them to re-centre the flange. I've fixed this on my 28/2, and my 35 Asph, and a friends 28/2. In fact a set of small screwdrivers seems a necessary piece of kit for the 28/2 as you need one for the three tiny screw that hold the front barrel on, they loosen by holding the lens hood while mounting and dismounting it.

 

Steve

[Malvolio]

The loose screw issue on the 28/2 is the precise reason I don't use the supplied hood on mine. Don't want to risk that loosening over time. Haven't noticed any degradation in image quality or flare without the hood

[wattsy]

I would rather not send such a new lens to full CLA, expensive too.

(Unfortunately out of warranty...)

 

If Steve's good suggestion to loosen then retighten the flange screws doesn't solve this, I think a trip to Leica might be worthwhile. My 28 Summicron went a bit odd last year and felt like it was going to fall apart (there was plenty of loose play in the barrel if you angled the lens downwards). Leica dealt with it free of charge (I bought the lens in 2006) and it came back feeling like new. (Incidentally, my problem wasn't the well-reported loosening of the front of the lens assembly which can be DIY fixed by tightening the little grub screws.)

[wattsy]

The loose screw issue on the 28/2 is the precise reason I don't use the supplied hood on mine. Don't want to risk that loosening over time. Haven't noticed any degradation in image quality or flare without the hood

 

Provided you are careful to mount and dismount the lens holding the lens barrel rather than the hood, there shouldn't be a problem.

 

For many years I used the hood from the older version of the 35 Summilux ASPH on the 28 Summicron but more recently I've gone back to using the original hood. The supplied hood is much easier to get on and off when changing filters and seems better suited to the task for which it was designed.