[Just1MoreDave]

I'm still hearing ideas if anybody has any that haven't been mentioned yet, though.

Maybe drill two holes through the filter rim, 180º apart, easiest from the inside of the filter to the outside. Then stick a metal bar, possibly a really long nail, through both holes, and use the bar for leverage. It might be hard getting large enough holes for the bar within the filter rim. A similar alternative is to use a hacksaw to cut slots or notches in the filter rim 180º apart. Put a plastic bag around the lens first and seal it with a rubber band to keep metal shavings out of the lens. If this fails, you have a really ugly lens now.

Breaking the filter glass is possible, but always requires more force than you hope to apply. Using a glass cutter might help but commits you even further to removing the filter. If the filter glass is gone, the rim can remain.

You could sell the lens on eBay and say it has always been protected by a filter.

[krs]

My oxyaceteylene torch works every time on frozen bolts.

Somewhat more seriously, spraying WD40 and letting it sit, doing it again, etc - I would think would eventually help loosen it up, and then apply some of the techniques described above to unscrew...

[OregonJim]

The freezer idea sounds best to me. The metal on the ring of the filter may shrink at a higher temperature than the metal of the lens itself. Even try heating (not over-heating) and try.

I'd be worried about condensation forming on the inner elements, possibly leaving water spots.

[Denis]

What you need to do is cool down the filter but not the lens. Put the lens filter down on a frozen surface to cool the filter, wait 10-15 minutes, apply pressure using a piece of rubber on the front surface to get even pressure and rotate. Keep doing it with longer cool down until it comes off. If that fails, your are SOL. BTW never use a lubricant as the lens can get contaminated.

[octavmandru]

This sounds like the best idea so far!

[newarts]

WD40 residues can be removed with acetone or mineral spirits (safer RE the plastic). Neither acetone nor mineral spirits should affect the lens coatings. Do not get either inside the lens.

Physically, the aluminum ring is stuck inside a plastic sleeve.

To separate them the aluminum must decrease in size compared to the plastic. Plastic expands (contracts) more than aluminum when heated (cooled.)

If both are heated (like with hot water run over the junction of the lens and filter) the plastic will expand more than the aluminum & will promote release.

If both are cooled the plastic will only grip the aluminum more tightly.

You might try rubbing an ice cube around the inside lip of the aluminum ring for maybe 30 sec. This should cool the ring more than the plastic lens & enable release. If that fails try liquid nitrogen inside the filter's lip.

If the aluminum is cooled and the plastic is heated the release will be most effective.

Iowa Dave

[xjjohnno]

Skip the WD40 idea, it's only going to make matters worse. You'll have a damaged thread that's locked the filter in place and if there's no movement short of butchering the filter by your preferred method it is stuck there.

[Stefan Carey]

May be useful as a last resort?

This works for loosening stuck jar lids without applying any force.

Gently tap around the circumference with the handle of a fork spoon or preferably a wooden handled kitchen utensil: Do it very gently, gently and do it for a little while, maybe a minute or so.

Could be a worth a try?

[dafiryde]

[QUOTE=krs;548686]My oxyaceteylene torch works every time on frozen bolts.

how about 5 lbs of C4

But on a serious note
if you have some patience, get a dremel tool, a magnifing light and some patience, it will peel off

Dave

[geauxpez]

I just removed a filter that was horribly jammed (cross threaded). I tried the rubber jar opener, mouse pad (usually works for me) and freezing. No dice. I finally got out the channel locks and after deforming it in several places, I finally got it to turn a little by pulling with the channel locks as I turned. No more filter.

[nanobaud]

You can also try heating with a hair dyer. Rotate the joint under hot air for a couple of minutes (heating from the side) then try to remove the ring using a rubber glove or similar grip. I use this method (actually a hotter heatgun when I know there is no plastic involved) to get tight front bezels off when I disassemble a lens for cleaning or adjustment.

nBd

[chse]

I was going to suggest the same method as below, use a freezer pack or just a container with frozen water and put the filter on it.
Be carful if you put the whole lens in the freezer you might get a lot of condensation, and humidity in the lens. Do it on a non-humid day if you have to.
DO NOT USE WD40!!!!! this is creeping oil, if you put to much it will creep in the front element (sooner or later) and you will get stains. If you try to remove the WD40 with solvent you might just drive it deeper into the lens.

What you need to do is cool down the filter but not the lens. Put the lens filter down on a frozen surface to cool the filter, wait 10-15 minutes, apply pressure using a piece of rubber on the front surface to get even pressure and rotate. Keep doing it with longer cool down until it comes off. If that fails, your are SOL. BTW never use a lubricant as the lens can get contaminated.

[TTQ225]

The advise given by POCO worked for me. I bought a lens with a cheap filter attached to it. The filter ring was deformed after being hit on one side and it was impossible to remove with bare hands. I was contemplating cutting of the filter with Dremmel tool. However, the mouse pad trick worked beautifully. Put a filter ring flat down onto the mouse pad (back surface) press the lens in firmly and twist.

[Donald]

lots of ideas, nothing working!

Screw threads work through competing forces of tension and compression when tightened. This is why the pushing, or just above, geauxpez's pulling while turning is the only method that will work sans lubrication: break one of the competing forces and screw threads become loose. Thermal cycling, much described above, also works to break the competing forces when the materials have sufficiently different thermal coefficients. Same with vibration or impact type tools.

If you have tried this, try again. Failing that, you'll have to do nothing or break the filter glass and destroy the remaining ring.

[itshimitis]

Ice in a bowl put the lens in the the ice face down for a minute then with rubber gloves on turn the filter. Just worked for me on a Canon EF 24 - 70 L lens.