Stiff/tight Focus Knobs when cold

[JohnJos]

General question regarding bins whose focus knobs become stiffer/tighter/harder-to-turn when the temperature becomes colder. I presume this is due to the type of grease/lubricant used by the manufacturer and not a mechanical problem.

Both my Pentax 8x32 DCF SP and my Browning 8x32 bins exhibit this behavior. On really cold days, say this morning when it was in the teens, these bins become effectively unusable.

Is this fixable? If so, by whom? The manufacturer or a third party repair center or me?

Thanks.

[JohnJos]

I did read that AP says they warm up in hand and turn easier but I guess I have not experienced that behavior.

[Kevin Purcell]

Do the Pentax 8x32 DCF SP have a specified range of operating temperatures? If it's inside the range then you'd expect warranty to cover it. I can't say I've seen one outside of M22/M24 mil specs for those bins.

I suspect it is the grease thickening though differential expansion or shrinkage might be an issue e.g. rubber is an odd material that expands as it cools. There isn't anything binding of the knob is there?

[Alexis Powell]

...my Browning 8x32 bins exhibit this behavior. On really cold days, say this morning when it was in the teens, these bins become effectively unusable...

My Browning 8x32 stiffen up in the cold, but then they seem to "break free" of their stiff lubricant. At that point, the focus turns smoothly but it feels dry (no "hydraulic" feel of the lubricant). Maybe your Browning aren't getting cold enough to make the jump? After they warm up, they return to normal again until the next use in the cold.

In the past, some photographers had their lenses and mechanical cameras "winterized"--some repair shops were able to replace the standard lubricants with multiviscosity alternatives that worked over a larger temperature range (winterized cameras were said to work fine at normal temperatures). I've not heard that this procedure is done any more, but it should be possible. It remains a great mystery to me why cheap binos can't be made with better lubricants.

--AP

[Simon S]

Most of the early Japanese binoculars suffer from this, and get to the point where you can hardly move them. Russian and German binoculars use a lower viscosity damping fluid, therefor not suffering the same trait.