[house]

I have a SMC Pentax 55mm f1.8 in excellent cosmetic and optical condition. There's no give, sound or perceivable slop in the lens at all. Curiously considering the above the focus ring has considerable friction when held in certain orientations. For portrait shots it's smooth with the camera grip downwards but really tight with the grip upwards. To me this suggests there must be some slop in the lens but I *really* cant find any. It appears to be immaculately put together. The lubricants are probably old and hardened but to my simple mind that shouldn't be affected by the lens orientation.

Does anyone has any idea what could be going on? Even better perhaps know how i might might fix it?

[Not a Number]

My guess is it being a matter of how the grease settled when it dried out. Perhaps the lens was stored for years with the front element facing up.

My Minolta 58mm f/1.4 would be very tight at the extremes of the focus throw and loose in the middle. Warming the lens up for a while on top of my audio amplifier would loosen the extremes until it cooled down again. No apparent ?play".

Taking the helicoid apart, cleaning and lubricating it solved the problem and it is "buttery/silking" smooth now throughout the range.

[Just1MoreDave]

You might get lucky and redistribute the grease by working the focus ring back and forth a lot. I tried adding new grease to one lens with uneven effort, hoping it would blend with the old stuff, but it didn't work. Also I think the K series lenses have well-shielded helix threads so you won't have much access without full disassembly.

[house]

I was hoping for a simpler solution than full disassembly and lubrication. Getting the correct lubricant seems non trivial. End result would probably be nice though.

Despite being a tiny lens the behaviour suggests that gravity somehow "bends" the lens making it touch nearby material.

[Not a Number]

Helimax-XP is designed for camera and telescope helicals. I and several other members have used this product with excellent results I recommend it.

Readily available from Amazon or eBay. Shipping might be more than the product if you are outside the US.

You could always do as disreputable sellers do and drip some lighter fluid in the threads. This might soften the grease for a short time but will do more harm than good. The lighter fluid is a solvent and dissolve oils will go places it shouldn't.

[house]

Helimax-XP is designed for camera and telescope helicals. I and several other members have used this product with excellent results I recommend it.

Thanks for the tip! Unfortunately it appears to be three times more expensive than the lens. At least via amazon will look for other places to get it.

[ZombieArmy]

Thanks for the tip! Unfortunately it appears to be three times more expensive than the lens. At least via amazon will look for other places to get it.

Yah but you need very little. Will last you years and many lenses.