Damage to Cross-Polarizer

<p>I have just obtained one of these:<br>

<a href="http://www.alanwood.net/photography/olympus/ring-cross-filter-pol.html">http://www.alanwood.net/photography/olympus/ring-cross-filter-pol.html</a><br>

There are at least 8 concentric rings of rainbow-like colours, extending for about 8mm inwards from the inner ring. These were present around nearly half of the circumference. After various manipulations with step-up rings, etc. I saw one end of the discoloured patch slowly disappear (after 24 hours it has not returned), as though a solvent had evapourated. (No solvent was involved, this is for illustration). If I compress the inner ring by pressing from both sides, front and rear, the remaining coloured pattern distorts slightly but reverts when the pressure is removed.<br>

OK. I have received a partial refund from the dealer. I now want to see what I can do to:<br>

a) Loosen the grip of the inner ring to see if that cures the problem<br>

b) If that does not work, remove the inner polarizer and either insert a new one (in the correct orientation) or<br>

c) Use a conventional one on the lens, leaving the central area clear, allowing narrow lenses to pass through, if of value.<br>

The outer polarizer is at risk of damage from any attempts to deal with the inner mount so I would welcome any advice as the whether the latter is likely to be detachable and, if so, whether it is screwed into place.</p>

<p>Sounds like the inner polarizer might be debonding... However, does it actually affect your images? If not I'd say leave it alone.</p>

<p>It's a spare so I can afford to work on it, with care. I haven't used it and it might affect some images and not others, as reflections are so variable. I would say that such damage to the outer ring would be of less concern but the light path to the lens needs to be optimised. With film any effects are not necessarily apparent at the time.</p>

<p>Be careful if you replace the inner filter. If it's a circular polarizer you'll need to make sure that it's inserted with the correct side out (as well as the correct rotational orientation relative to the outer filter) otherwise it won't polarize.</p>