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03-15-2009, 03:12 AM   #1
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What is that pearl on the side of old manual lenses?

I have a couple of old manual lenses M50/2, A50/1.7 and K55/1.8. It may be a stupid question, but what is that little pearl button stuck on the side?

03-15-2009, 03:30 AM   #2
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It is there as an tactile assist for changing lenses in places too dimly lighted for you to spot the red dot.
03-15-2009, 03:30 AM   #3
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On my old Super A film camera, the "pearl" aligns with the lens release button on the body, and acts as a tactile aid to orienting the lens when attaching it. I actually found it more convenient than the red dot.

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03-15-2009, 03:31 AM   #4
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I am not sure of the manufacturers purpose of the pearl. However, it aligns up with the lens release button on the side of the lens opening. Newer lenses have a red dot to line up with the red dot on the camera. That's all I can see it being used for.

03-15-2009, 03:32 AM   #5
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Wow! We all nail the answer within the same minute!
03-15-2009, 03:32 AM   #6
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Ordinarily, the orange dots on the metal base of the lens and the lens-mount on the camera body had to be aligned before twisting the lens till it clicked and locked. The white globule was meant to line up with the white mark on the self-timer lever to achieve the same thing in poor light.
This was applicable only to cameras which had the self-timer with the white mark e.g. the MX. For DSLRs a possible indicator of alignment could be obtained by lining up the globule slightly above the SR logo on the body. However, this is not its purpose and a mark with a wax crayon on the body could achieve this end better.
03-15-2009, 03:38 AM   #7
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I thought it was a beauty spot.
03-15-2009, 06:07 AM   #8
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I find it useful and wish they would put it back on the new lenses. Couldn't cost much.
thanks
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03-15-2009, 07:25 AM   #9
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QuoteOriginally posted by barondla Quote
I find it useful and wish they would put it back on the new lenses. Couldn't cost much.
thanks
barondla

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I tend to read manuals and I picked up on the white bump very early, so I don't really search for that orange dot with M and earlier lenses.

The orange dot isn't as frustrating as finding the green dot when mounting a Tamron adapter, though.

Last edited by monochrome; 03-15-2009 at 03:33 PM.
03-15-2009, 08:03 AM   #10
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I recently noticed the f-number indicator is aligned with the red dot (which is sometimes hard to see.) Now I use the f-number indicator for alignment when mounting a lens.

Iowa Dave
03-15-2009, 11:11 AM   #11
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QuoteOriginally posted by chhayanat Quote
The white globule was meant to line up with the white mark on the self-timer lever to achieve the same thing in poor light.
It may have lined up with the self-timer, but most people (including myself) used it by FEEL because it was designed to line up with the lens release lever on the body. That meant you could change lenses in complete darkness, an ability that came in handy when I did astrophotography.

Unfortunately the release lever is in a slightly different position on the digital camera bodies so it's not quite as useful for that any more.
03-15-2009, 02:56 PM   #12
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QuoteOriginally posted by Sean Nelson Quote
It may have lined up with the self-timer, but most people (including myself) used it by FEEL because it was designed to line up with the lens release lever on the body. That meant you could change lenses in complete darkness, an ability that came in handy when I did astrophotography.

Unfortunately the release lever is in a slightly different position on the digital camera bodies so it's not quite as useful for that any more.
No, it was my mistake. It did not line up with the self-timer but with the lens release lever as stated by you and several others in this thread. I should have checked the MX body which was lying a few feet away before posting.
03-16-2009, 04:19 AM   #13
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Thanks for your replies. It seems obvious now.
03-16-2009, 07:48 AM   #14
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QuoteOriginally posted by Damn Brit Quote
I thought it was a beauty spot.
You mean they aren't real pearls??
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