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mechanical aperture lenses long term damage on adapter?
#1
Dear fellow zoners,



Owning a few OM mount lenses that I use every now and then on an adapter, it came to my mind that the aperture lever spring might get worn out if the lens stays on the adapter constantly.



I suppose you know what I mean but in case of...



OM cameras, just like many other, meter with the lens wide open and it is at exposure time that the aperture lever is pushed by the camera body. The aperture is then closed -or left wide open- according to the lens aperture ring.



Now, when you mount these lenses on an adapter to use on another camera, or even a macro extension tube from the same camera maker, this lever is locked in stopped down position by a little tooth on the adapter. This is necessary as other cameras don't have any mechanical means to operate this aperture lever. In effect, it means that the aperture lever spring is compressed permanently on an adapter.



I have absolutely no knowledge of spring mechanics but my impression is that a spring held compressed permanently will lose its strength over time. Or have spring mechanics been mastered so well for ages that no one should ever worry about it <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Rolleyes' />?



Since then, I've been carefully leaving my lenses unmounted. I suppose it's the best.



Greetings,

S.
#2
It may be enough to leave it at maximum aperture between uses. There should be no or very little compression then.



-Lars
#3
On alpha mount, is it the opposite way around? The aperture is sprung closed by default, and needs to be pushed open. The thing is, the rear lens caps do push the aperture open for storage. So at least in their case they think there is some reason that would be advantageous to do and they're not worried about the springs.
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#4
[quote name='larsrc' date='05 July 2010 - 07:28 PM' timestamp='1278354524' post='838']

It may be enough to leave it at maximum aperture between uses. There should be no or very little compression then.



-Lars

[/quote]



Good idea, thanks.



After checking a few lenses, my Tokina RMC 135mm shows its spring and I reckon it would be fearly easy to replace. No such luck on the Zuikos.
  


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