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05-30-2013, 12:30 AM   #1
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Aperture ring ball bearing size and availability for M50 1.7

Well I thought I was being careful...

But since I'm asking, obviously something went wrong.

I'd like to find a replacement ball bearing that provides the aperture clicks on my M50 1.7

To do that I need two bits of info. 1) is the size in case I were to order my own (likely in a package of 100 or some crazy amount). 2) would preferably be someone who was in my same position and might just happen to have one of their remaining 99 to spare for a reasonable price.

Any help on either front would be greatly appreciated!

05-30-2013, 01:06 AM   #2
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https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/84495-missing-ball-bearing.html
05-30-2013, 01:44 AM   #3
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Might just be easier to acquire a broken/crappy M lens of similar physical size. Can't imagine that the aperture ball wasn't a shared part over multiple lenses.
05-30-2013, 11:29 AM   #4
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Or aquire an A lens and use its ball. That way you have 2 usable lenses Clickless aperture might be cool for video - has anyone tried?

05-30-2013, 11:39 AM   #5
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QuoteOriginally posted by kakapo Quote
Clickless aperture might be cool for video - has anyone tried?
News Shooter | The Lens Doctor: De-clicking in the UK
05-31-2013, 09:02 AM   #6
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I am pretty sure that the M50/1.7 bearing size is 2mm, shared with many other M series lenses. I have never measured it. Smaller bearings work but don't feel right. The typical A series size is 1.5mm, a measurement I am sure of. Micro-Tools has suitable bearings in bags of 5 for reasonable costs.

The clickless aperture ring for video is a great trend for lens disassemblers like me. Now there is a market for losing parts! The typical Pentax design uses a bearing and spring to take up any slack between the lens body and ring. Without the bearing, the clicks go away but the ring won't be damped like a focus ring either. The friction will depend on machining.
05-31-2013, 09:26 AM   #7
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One of the wonders of the world "How do aperture ball bearings disappear"

I talk under correction , but the one I actually removed from my M50/1,4 with the aperture lever, was 1.5mm if I remember correctly. Easier to use in Av, and soundless operation if you shoot video...
05-31-2013, 09:40 AM   #8
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Yes, Micro-Tools has them, but I have found that it's OK without the click bearing ... lost one recently is the re-lubing of a Helios 44M-4 ... J

05-31-2013, 04:22 PM   #9
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Micro-Tools, here I come!

Thanks for the recommendation. From memory it looked closer to 1.5mm so I think that's what I'll go with. Hopefully it will work.
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