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12-22-2009, 08:02 AM   #1
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Snappy, oil and brassing???

As I browse the Marketplace I often see lenses described with things such as snappy aperture, oil-free blades or dry blades, and no brassing. What is a snappy aperture? What happens when oil gets on the blades, and is this common and repairable? Finally, what is brassing?

Thanks.

12-22-2009, 08:17 AM   #2
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QuoteOriginally posted by builttospill Quote
As I browse the Marketplace I often see lenses described with things such as snappy aperture, oil-free blades or dry blades, and no brassing. What is a snappy aperture? What happens when oil gets on the blades, and is this common and repairable? Finally, what is brassing?

Thanks.
I'll give this a shot based on my understanding of the terms. A snappy aperture refers to the way the lens came from the factory new. As correct exposure is directly related to how smoothly the blades open and close it is very important. Blades that are dry or gummed up with oil will not perform as accurately and will require a cleaning to operate properly. The condition is not terminal but it will cost you to send it out for repairs by a qualified technician. Some forum members disassemble and clean their lenses but I'm not that brave. Brassing refers to general wear and tear a lens or camera body sustains over time and use. Paint wears off various high points and reveals the metal (brass?) beneath. It is purely cosmetic and won't effect the performance of the lens or camera body. Hope this helps.

Tom G

Last edited by 8540tomg; 12-22-2009 at 11:13 AM. Reason: typo
12-22-2009, 08:48 AM   #3
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Not sure if this adds much to info in previous post.

When lens gets hot, sometimes helicoid grease melts and drips on aperture blades; helicoid grease also can break down into less viscosity components which can drip. Too much oil on blades can make auto aperture operate too slowly to fully stop down before shutter operates, causing overexposure. The aperture in my 85/1.8 has a lot of oil on it and it operates too slowly to use in auto mode on my spotmatics but in manual mode is not a problem.

Brassing refers to paint rubbed off revealing the bare metal underneath. Brassing usually indicates much use, not abuse, as body scratches and gouges would indicate.
12-22-2009, 10:13 AM   #4
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Just to add my small bit, snappy aperture is very important. When evaluating a lens, you should examine the auto aperture motion (flick the lever or depress the pin) at all apertures. Make sure the movement is swift and without binding when both opening and closing. Make sure that the movement is symmetrical as well. The most common cause of slow/sticky aperture is oil on the blades. As mentioned above, oil may slow or even jam the movement of the iris blades.

Another small note regarding oil on the blades. The issue of oil primarily applies to auto-aperture lenses. Manual (vintage only) and pre-set aperture (uncommon) lenses often have a small amount of lubricant present and visible on the blades. This is normal for these lenses and is not a cause for alarm unless the amount is excessive (drippy). Examples of pre-set aperture lenses currently in vogue include the Russian Jupiter-9, Helios 44-2/44-3, Helios 40-2, and various other off-brand long telephoto lenses.

Steve

12-22-2009, 10:55 AM   #5
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I think Steve has made a good point. If you are want to try an older lens (where auto aperature won't be used...like on a Takumar), as long as the blades work properly, and the oil isn't so excessive that it could drip onto something, oil on the blades doesn't mean a thing.
12-22-2009, 01:03 PM   #6
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Thanks for the replies. I have recently acquired a 135 Tak 2.5 and I'm thinking of listing it for sale here with a few other items and as I was inspecting it there are a couple small grease spots on the blades, but they don't affect operation and it's not an auto aperture lens anyway.
12-23-2009, 08:41 PM   #7
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mmmm...I'm fairly certain the 135/2.5 lenses are indeed auto-aperture; the aperture is operated by a pin on the mount end -- not electronic, but mechanical.

The second version S-M-C (6 elements/6 groups, first was 5/4) is an excellent lens, highly sought after...
12-24-2009, 09:39 AM   #8
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QuoteOriginally posted by rhodopsin Quote
mmmm...I'm fairly certain the 135/2.5 lenses are indeed auto-aperture; the aperture is operated by a pin on the mount end...
+1

Auto aperture refers to whether a lens has a mechanism to stop down automatically just prior to exposure and reopen immediately afterward. The vast majority of available used lenses are auto aperture, the exceptions being those with fully manual (duh...), semi-auto, or pre-set aperture.

The confusion arises due to common usage of the term "manual" as applied to lenses that don't auto-focus and/or don't support P or Sv modes for exposure automation (lack the "A" position on the aperture ring). It is best avoid mixing terminology with older lenses.

Steve

BTW...No Pentax lenses offer auto aperture or aperture control via any electronic or electrical connections. All use a mechanical linkage for this function.

12-24-2009, 09:51 AM   #9
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QuoteOriginally posted by stevebrot Quote
+1

Auto aperture refers to whether a lens has a mechanism to stop down automatically just prior to exposure and reopen immediately afterward. The vast majority of available used lenses are auto aperture, the exceptions being those with fully manual (duh...), semi-auto, or pre-set aperture.

The confusion arises due to common usage of the term "manual" as applied to lenses that don't auto-focus and/or don't support P or Sv modes for exposure automation (lack the "A" position on the aperture ring). It is best avoid mixing terminology with older lenses.

Steve

BTW...No Pentax lenses offer auto aperture or aperture control via any electronic or electrical connections. All use a mechanical linkage for this function.
Well... sure, most M42 lenses are "auto-aperture" on screwmount bodies, but none of them carry over the same functionality on any Pentax-K body, or any other mount for that matter. What you just wrote above is even more confusing that what you were trying to dispel.

Auto-aperture, on Pentax K-mount bodies, always refers to A-series lenses (and newer) that have electrical contacts that will automatically calculate exposure in changing light conditions, and allow the use of all modes on the camera instead of just B and M. It never refers to the archaic M42 auto pin that controls those lenses' diaphragms.

And yes, the aperture of K-mount lenses is linked mechanically to a lever in the body, but the aperture you're setting the lens to can and will definitely be controlled electronically in an A-series and newer lens.

If this was 40 years ago your writings would be accurate and relevant, but considering what has happened in the past 40 years it's borderline misinformation, especially on this forum.
12-24-2009, 11:35 AM - 1 Like   #10
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except for the fact in this thread we are discussing a 40-year-old lens
12-24-2009, 12:11 PM   #11
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QuoteOriginally posted by rhodopsin Quote
except for the fact in this thread we are discussing a 40-year-old lens
No, in this thread, we are discussing terms that are not familiar to a newer member of this forum. To insist on an archaic usage of a term, especially considering the strong distinction in the Pentax line of lenses between MF electrically-controlled auto-aperture lenses and AF lenses, a distinction that other camera systems such as Canon, Nikon, Minolta, and Olympus don't have, will do nothing but add to the confusion the OP is already experiencing.
12-24-2009, 12:48 PM   #12
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QuoteOriginally posted by wallyb Quote
No, in this thread, we are discussing terms that are not familiar to a newer member of this forum. To insist on an archaic usage of a term, especially considering the strong distinction in the Pentax line of lenses between MF electrically-controlled auto-aperture lenses and AF lenses, a distinction that other camera systems such as Canon, Nikon, Minolta, and Olympus don't have, will do nothing but add to the confusion the OP is already experiencing.
Please refer to message #6 by OP...Thank you for the additional information; I was not aware of the newer distinction, which undoubtedly is confusing to folks.
12-24-2009, 01:25 PM   #13
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QuoteOriginally posted by rhodopsin Quote
Please refer to message #6 by OP...Thank you for the additional information; I was not aware of the newer distinction, which undoubtedly is confusing to folks.
Right, and in post #6, OP is talking about newer auto-aperture Pentax lenses that use wide-open metering. Since the "auto-aperture" system present in M42 lenses does not function in any way whatsoever on any camera but a screwmount camera, an M42 screwmount lens is not an auto-aperture lens. It will always be put into M mode and used with stop-down metering on an adapted camera. So again, OP was speaking correctly in that post in how oily blades do not matter on a lens that you are using with stop-down metering since it has no coupling, and introducing an archaic meaning of the term "auto-aperture" will only be a disservice to an otherwise informative thread.
12-24-2009, 02:56 PM   #14
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Wally,
I respectfully disagree with you on this. Being old enough to know first hand the evolution of lens terminology, I know for a fact that the term "Auto" was never applied to A-contact K-mount lenses except as it refers to their auto aperture. The "A" on the aperture ring refers to shutter priority exposure automation only. There was no magic proclamation in the early 1970s when the first Sv mode cameras (not Pentax) were introduced that changed the definition of "Auto" as it applied to lenses.

Probably the best way to put this is to step firmly outside Pentax land. Pentax seldom used the term "Auto" in any of their lens names. The term was common with other brands and always referred to auto vs. manual/pre-set apertures. This practice continued well in the 1980s. This was the case for lenses in the Konica and Canon mounts even after those companies released lenses that supported shutter priority exposure automation starting in about 1970. Exposure automation was and still is a BODY, not a lens, function.

Whether an adapter provides support for the auto aperture feature is not pertinent. An auto lens is an auto lens by nature of its design as much as it retains its focal length regardless of sensor size.

Much as you might want to change the terminology, you are up against 50+ years of common usage as well as the opinions of the hordes of vintage camera and lens users out there.

Steve

BTW...there are some of us that still use M42 bodies. If fact, there are some fairly modern cameras that were still made with that mount. And I don't mean Zenits!

Last edited by stevebrot; 12-24-2009 at 03:03 PM.
12-24-2009, 03:09 PM   #15
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Steve, you're writing a whole lot about nothing. There's absolutely nothing to "disagree" with. "Auto-aperture" in Pentax terminology refers to A-mount and newer lenses, with electrical contacts. Since we are on PentaxForums.com and not VintageCameraInfo.com, there is no need to try to "correct" OP's already proper use of the term "auto-aperture" to refer to KA, F, FA, and DA Pentax lenses.

Period. I'm not trying to change any terminology. I'm not trying to "fight conventional wisdom and camera users", or any other heroic statements you'd like to add to your faulty cause. The terminology is already there, and it means 100% exactly what I say it means in the context of OP's posts. What do you think "A" in the A-series of lenses stands for? By your writing, it fairly evident that you don't understand what a KA lens is or how it functions, and that you are stuck in an era before then. There's no relevance to OP's concern in any of what you've written.

Further, your entire writing style is schizophrenic as you're agreeing with me here:
QuoteQuote:
I know for a fact that the term "Auto" was never applied to A-contact K-mount lenses except as it refers to their auto aperture.
And you are also simply wrong here (as well as in other places):
QuoteQuote:
Exposure automation was and still is a BODY, not a lens, function.
because exposure information of KA and newer lenses is stored in an IC inside the lens, and transmitted to the camera. We're not talking about aperture linkage, we're talking about full automatic aperture control, and you're missing that point entirely.

Last edited by wallyb; 12-24-2009 at 03:22 PM.
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