Joe Blow wrote:
........
Do NOT use the freezer. That makes metal shrink
and the connection even tighter. ........
If it were aluminum for both the lens threads and
the filter rim, that will be quite true. But this is a
metal filter in plastic lens threads. The metal filter
rim WILL shrink noticeably more than the plastic
lens threads, and thus be easier to unscrew.
OTOH severe cold can make plastic brittle, so use
caution handling the lens. Perhaps try the regular
refrigerator section before resorting to the freezer.
It might be enuf temperature change to do the job.
Aluminum's very susceptible to minor temperature
changes in terms of expansion-contraction, while
plastic will barely respond at all, size-wise.
If you use the freezer, beware of condensation as
the lens enters the general room air. In a humid
room, you could use a large-ish clear plastic bag
as a work space. Flatten the bag and seal it. Cut
two snug holes for hands. Work the job inside the
bag. [Lens also enters the bag thru a hand hole]
Lens can be inside the bag before entering freezer.
Purpose of flattening the bag is not have too much
air with room humidity in there.
Other than rubber bands and wrenches sometimes
I just screw a spare filter onto the stuck one and
tape them together. Screw the second one all the
way on, so it reinforces the stuck one against your
hand strength deforming its roundness. IOW, don't
jam the second one but don't leave it too loose. A
filter rim is so thin that a strong hand grip slightly
temporarily deforms it, causing it to grip tighter :-(
Rubber bands also limit deformation, by providing
a more sure grip with less hand strength applied.
Filter wrenches distribute the force in a more even
pattern, to avoid deformation, but most wrenches
are slippery hard plastic, so the rubber band helps
the wrench as well.
Do try all these mechanical maneuvers before you
resort to the freezer !
The OP suggests awareness of stressing the focus
or zoom mechanism. Good thinking. Try to grip the
lens only by the component directly attached onto
filter. If it's an extendable zoom barrel, extend it
and grip only the cylinder that carries the filter. If
the "safe grip zone" is very narrow, a rubber band
can help you get a grip there as well. If it's one of
those lenses with no external moving parts [with
internal zoom and internal focus] things are easier
safety-wise. Just grab the whole lens barrel.
FWIW, I stepped up the filter size on some lenses
that have jam-prone plastic threads. It's OK if the
step-up ring gets kinda jammed. This converts a
lens to a larger METAL filter receiving thread. Cost
of filters increases a bit, but digital photo needs
far fewer filters than were needed with film. I go
two "steps", 55>62 or 62>72 etc, etc , to prevent
vignetting ... except for the longer FLs where one
step is OK due to the narrower FoV. The reversible
petal hood is useless if you install step-ups. Many
hoods ... not all ... are nearly useless anywho.
Sorry about the looong post but I've learned very
many tricks about stuck filters over the years.