Canon nFD 24mm f2 front ring - unscrew or lever off?

<p>Hi. Does anyone know if the Canon nFD 24mm f2 front ring should be removed by unscrewing it, or if the correct way is to lever the ring off?<br>

<br />According to this guide for the f2.8, the front ring should be removed by unscrewing it counter clockwise:<br /><a href="http://www.dpreview.com/forums/post/57208104">http://www.dpreview.com/forums/post/57208104</a><br /><br />According to this question, this may not be the case for the f2:<br /><a href="https://www.flickr.com/groups/24098559@N00/discuss/72157635788366405/">https://www.flickr.com/groups/24098559@N00/discuss/72157635788366405/</a><br /><br />The nFD 50 f1.4 front ring apperantly don't have threads: <br /><a href="http://www.gregpotter.net/canon-fd-50-14-disassembly.html">http://www.gregpotter.net/canon-fd-50-14-disassembly.html</a><br>

<br />Any help appreciated.<br /><br /><br /></p>

<p>I had my FDn 24/2 serviced some years ago, and the front ring does indeed screw off (I'm not sure in which direction). However, the ring was on so tight that my technician was unable to unscrew it (he didn't want to apply too much pressure and risk cracking the front element). His solution was to machine a couple of slots into opposing "sides" of the ring so that he could use a different tool to unscrew the ring without exerting too much force. He even painted the notches he had cut so the ring looks unmodified.</p>

<p>Or carefully drill two small neat holes opposite each other to take a spanner wrench or similar.</p>

<p>Thanks for the information.<br>

I think drilling/machining holes is beyond my capabilities.<br>

I'll give a 52mm rubber lens repair tool a shot first.</p>

<p>Let us know how using the rubber stopper, aka 'lens repair tool' works for you. I run into this problem periodically. Not with the nFD 24mm, but with others. I've been procrastinating buying a set of rubber stoppers.</p>

<p> </p>

Just a follow up for future reference.

 

I disassembled a 24mm f2.8 FDn lens for cleaning and found that the plastic nameplate ring was screwed in but no amount of turning with a variety of friction devices would release it. This was due to adhesive having been use under the ring to prevent it coming loose.

My solution was to pry it off since the plastic is slightly flexible and could stand distortion. I used a thin guitar pick (plectrum) slipped between the lens surface and ring then worked it around the circumference to lift it slightly followed by a small screwdriver tip to pry it upwards. The lens surface was protected by small pieces of card (very important).

 

Other FD lenses differ in the way the ring is held. The 28mm f2 FDn lens has a metal screw in ring which unscrews with enough friction applied.

The 100mm f2.8 FDn has a plastic clip-on ring which needs to be pried off.