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08-28-2012, 02:51 PM   #1
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The aperture...when manual lens is not in use

So, what's best for the aperture when a manual lens is not in use so it doesn't become sticky? Is it best to:
1. Leave it wide open?
2. Closed down all the way?
3. Somewhere in the middle?

Just wondering if one is better than the other to maintain the 'health' of the aperture. Or, one way for a while, then the other for a while? Or, does it not really matter?

Steve

08-28-2012, 03:03 PM   #2
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Out of habit, I normally keep manual lenses at minimal aperture (or at A for lenses with pkA mount), but I don't think it matters.
08-28-2012, 03:19 PM   #3
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Since gravity makes things (including oil) fall, apart urge blades up may be a lot more important
08-28-2012, 03:54 PM   #4
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QuoteOriginally posted by Spodeworld Quote
manual lens is not in use so it doesn't become sticky?
"Sticky" 7 out of 10 are from oil.
Seperation of the grease is the source and so it is possible that storing the lenses in very warm conditions is a no-no.
A car in the sun and the trunk or glove box is a common thing.

Only a few times was it due to the internal spring crapping out.
If the spring is under tension to keep open or closed may dictate if you should store it wide or narrowed.
All my M series K-mount lenses are under tension when the aperture is held wide.
The few K series K-mount lenses are the same.
My Tamron manual focus lenses are also under tension when held wide.

That my two cent.

08-28-2012, 04:17 PM   #5
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I appreciate the feedback, but I am wondering if there is a rule of thumb as to whether the aperture is best left wide open, closed or somewhere in the middle when stored? Or, does it not matter?
08-28-2012, 04:47 PM   #6
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For your concern about "sticky", wide or closed is not much a difference. Keeping it out of heat is a better protection against stickyness.

Spring life, and possible unintensional mishaps... closed/small, if a Pentax K or M and retracted to the infinity as to not risk disconnection of internal armatures or lever from drop trauma.
08-28-2012, 06:30 PM   #7
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My lenses are in a display cabinet and pretty easy to get to. If I walk by and I have nothing better to do I'll grab one and move the aperture ring back and forth a few times to keep everything freed up. They all end up getting it done about once every other month.
08-29-2012, 05:46 AM   #8
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lets recap

in summary there are several things to consider.

Aperture of unmounted lens vs Lens type
- M42 lenses come in 3 varieties, preset, auto, and those with an auto manual switch. Of these lenses, because preset use manual aperture setting only, you can put them where you want, but sticky / slow apertures are generally not a problem. Auto only you have an option, either wide open, or if the lens cap depresses the auto pin, to the set aperture. M42 lenses with an auto manual switch leave you the option of setting the switch to manual and putting the aperture where you want it.
- K mount and later lenses , except DA lenses without aperture ring, you can put the aperture where you want it
- DA lenses (those with no aperture ring) offer no option at all, the lens is always stopped down when un mounted.

Regardless of where the aperture is set, the blades are still prone to oil contamination (the cause of sticky blades). Oil contamination comes from oil released out of the grease on the focusing helix. Grease releases oil due to mechanical working (where the structure of the grease is broken down and can no longer hold the oil), temperature, and vibration.

Since we are talking storage, cool is better than hot and stable vs vibration environment is better.

But as I noted above, since oil will largely flow down the best storage would be to have each lens stored with the aperture at the highest part possible for each lens. this will generally lead to the mount cap facing up, although not for presets that have the aperture generally forward.

The main concern is that if oil were to flow out of the focusing helix, that it does NOT flow due to gravity onto the blades.

open or closed is not relevant, as once there is oil around the blades, it will contaminate them with each actuation.

08-29-2012, 06:46 AM   #9
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Thanks! And this is a particularly interesting quote:

QuoteOriginally posted by Lowell Goudge Quote
But as I noted above, since oil will largely flow down the best storage would be to have each lens stored with the aperture at the highest part possible for each lens. this will generally lead to the mount cap facing up, although not for presets that have the aperture generally forward.
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